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Advanced Production Technologies of Maize
Abstract
Maize (Zea mays L.) is the third important cereal crop after rice and wheat grown around the globe. Byproducts obtained from maize grains are having high value of calories from seed. Feeding of maize grains has intensely increased in poultry and livestock industries. It is a high-yield commodity crop as well as a source of food security in many developing countries in Latin America and sub-Saharan Africa. Maize growing on scientific lines under climate uncertainty is need of the day.
... Environmental elements strongly influence the growth and ontogenetic development and yield formation in maize (Bonelli et al. 2016;Ahmad et al. 2019;Hussain et al. 2019;Abbas et al. 2020). Adjusting planting date, temperature (T) mainly when planting window is shortened through weather and/or management challenges, is very critical to harvest higher crop productivity (Florio et al. 2014;Abdala et al. 2018;Ijaz et al. 2019a, b;Shahzad and Ahmad 2019;Sher et al. 2019;Zahoor et al. 2019). ...
... Owing to variations in maturity of hybrids (being photo-insensitive in nature), time-span of crop growing season, the best sowing date for spring and fall maize hybrids vary amongst various zones besides seasonally within zones (Varma et al. 2014;Tian et al. 2015;Yan et al. 2018). To harvest highest grain yield and profitability, it is indispensable that the maize hybrids with the right maturity to be chosen for sowing with respect to efficient utilization of sowing window by the farmer community of given area (Tsimba et al. 2013;Abbas et al. 2017;Ali et al. 2018;Hussain et al. 2019;Tariq et al. 2019). ...
Maize can be sown in spring and fall seasons in Pakistan under maize–maize cropping system. Due to seasonal variability in meteorological parameters, optimization of planting time for maize hybrids is vital to harvest improved productivity in maize-maize system. This study was designed to explore the effect of diverse sowing dates on phenology, growing degree days (GDDs), photo-thermal-units (PTUs) and helio-thermal-units (HTUs), and its impact on radiation-use-efficiency (RUE) and grain yield (GY) in different maize hybrids under maize-maize cropping system. Two-year experiments were conducted to optimize planting dates for hybrids during 2016 and 2017. In spring, three hybrids were sown on Jan 15, Feb 5, Feb 25, Mar 15 and Apr 05. During fall, three hybrids were planted on Jun 15, Jul 05, Jul 25, Aug 15 and Sept 05. Results showed that spring early (Jan 15), while fall late (Jul 25) sowing took more days to complete 50% tasseling, silking and maturity. However, maize sown on Feb 05 and Jul 25 accumulated more GDDs to attain 50% tasseling, silking and maturity. Maize sown on Feb 05 and Jul 25 had more leaf area index (LAI), crop growth rate (CGR), RUE and GY, which was linked with higher accrual of GDDs, PTUs and HTUs. Likewise, hybrids P-33M15 and P-30R50, during spring and fall observed higher values of all above cited traits. Moreover, positive-correlation was witnessed among days taken to complete different phenophases, LAI, CGR and 1000-grain weight, total biomass, GY and RUE. However, higher GY and RUE was obtained in spring than fall. In conclusion, maize sown on Feb 05 and Jul 25 using hybrids P-33M15 and P-30R50, during spring and fall crops, respectively produced more GY and higher RUE due to more accumulation of GDDs, PTUs and HTUs. Thus the spring season seemed more productive than fall season under maize-maize cropping system.
... Environmental elements strongly influence the growth and ontogenetic development and yield formation in maize (Bonelli et al. 2016;Ahmad et al. 2019;Hussain et al. 2019;Abbas et al. 2020). Adjusting planting date, temperature (T) mainly when planting window is shortened through weather and/or management challenges, is very critical to harvest higher crop productivity (Florio et al. 2014;Abdala et al. 2018;Ijaz et al. 2019a, b;Shahzad and Ahmad 2019;Sher et al. 2019;Zahoor et al. 2019). ...
... Owing to variations in maturity of hybrids (being photo-insensitive in nature), time-span of crop growing season, the best sowing date for spring and fall maize hybrids vary amongst various zones besides seasonally within zones (Varma et al. 2014;Tian et al. 2015;Yan et al. 2018). To harvest highest grain yield and profitability, it is indispensable that the maize hybrids with the right maturity to be chosen for sowing with respect to efficient utilization of sowing window by the farmer community of given area (Tsimba et al. 2013;Abbas et al. 2017;Ali et al. 2018;Hussain et al. 2019;Tariq et al. 2019). ...
Maize can be sown in spring and fall seasons in Pakistan under maize–maize cropping system. Due to seasonal variability in meteorological parameters, optimization of planting time for hybrids is vital to harvest improved productivity in maize-maize system. This study explored the efect of diverse sowing dates on phenology, growing degree days (GDDs), photo-thermalunits
(PTUs) and helio-thermal-units (HTUs), and its impact on radiation-use-eiciency (RUE) and grain yield (GY) in diferent maize hybrids under maize-maize cropping system. Two-year experiments were conducted to optimize planting dates for hybrids during 2016 and 2017. In spring, three hybrids were sown on Jan 15, Feb 5, Feb 25, Mar 15 and Apr 05. During fall, three hybrids were planted on Jun 15, Jul 05, Jul 25, Aug 15 and Sept 05. Results showed that spring early (Jan 15), while fall late (Jul 25) sowing took more days to complete 50% tasseling, silking and maturity. However, maize sown on Feb 05 and Jul 25 accumulated more GDDs to attain 50% tasseling, silking and maturity. Maize sown on Feb 05 and Jul 25 had more leaf area index (LAI), crop growth rate (CGR), RUE and GY, which was linked with higher accrual of GDDs, PTUs and HTUs. Likewise, hybrids P-33M15 and P-30R50, during spring and fall observed higher values of all above cited traits. Moreover, positive-correlation was witnessed among days taken to complete diferent phenophases, LAI, CGR and 1000-grain weight, total biomass, GY and RUE. However, higher GY and RUE was obtained in spring than fall. In conclusion, maize sown on Feb 05 and Jul 25 using hybrids P-33M15 and P-30R50, during spring and fall crops, respectively produced more GY and RUE due to more accumulation of GDDs, PTUs and HTUs. Thus the spring season seemed more productive than fall season under maize-maize cropping system.
... Most maize harvests in Nigeria is done manually because the predominant producers are smallholder farmers with limited or no capacity to afford the application of mechanical support [35]. The harvesting can be done either when the maize is fresh or dry depending on the need [36]. ...
Maize products are very significant for domestic consumption as well as industrial uses both locally and globally. For there to truly appreciate the spread of maize production in Africa, the geospatial mapping and subsequent comparison of the value chain for Nigeria and Rwanda were necessitated hence the purpose of this study. Farm mapping geospatial techniques and remotely sensed data were used for both Nigeria and Rwanda in this study. GIMMS Global Agricultural Monitoring data from United States Department of Agriculture (USDA) were adopted for Nigeria and Rwanda. The crop calendars of both countries were examined which thereafter reviewed a marked distinction among them. The results of the agroecological zones for the two countries showed a significant variation in their distribution and types, which in turn affect both the planting and harvesting of maize; storage, marketing, processing, and policy framework for maize products value chain in Nigeria and Rwanda. Mapping of the two countries was carried out and the normalized differential vegetation index (NDVI) and the policy associated with maize value chains were checked and reported.
... Maize is grown during both spring and autumn growing seasons in Pakistan Fatima et al., 2018;Abbas et al., 2017;Ahmad et al., 2016). After wheat and rice crop, maize crop is ranked 3 rd position and mostly (95%), it is grown in Punjab and Khyber Pakhtunkhwa provinces in Pakistan (Ahmad et al., 2019;Ahmed et al., 2019aAhmed et al., , 2017Hussain et al., 2019;Tariq et al., 2019). Total growing area was almost 1.32. ...
... Maize is grown during both spring and autumn growing seasons in Pakistan Fatima et al., 2018;Abbas et al., 2017;Ahmad et al., 2016). After wheat and rice crop, maize crop is ranked 3 rd position and mostly (95%), it is grown in Punjab and Khyber Pakhtunkhwa provinces in Pakistan (Ahmad et al., 2019;Ahmed et al., 2019aAhmed et al., , 2017Hussain et al., 2019;Tariq et al., 2019). Total growing area was almost 1.32. ...
Optimum sowing date and most suitable hybrid are two main adaptation strategies for maize crop for managing the unfavorable weather circumstances. The objective of this research was to determine the optimum sowing date and hybrid during spring and autumn seasons. Field trials were carried out in spring and autumn seasons during 2016 and 2017 at Agronomic Research Area, Bahauddin Zakariya University, Multan, Pakistan. During spring season, three hybrids i.e., P-33M15, M-DK6525 and S-NK8441 were allocated in main plot and five sowing dates i.e., 15-January, 5-February, 25-February, 15-March and 5-April, were placed in sub plot during both years. During autumn growing season, three autumn hybrids i.e., P-30R50, M-DK6714 and S-NK6621 were placed in main plot and five sowing dates i.e., 15-June, 05-July, 25-July, 15-August and 5-September, were applied in sub plot. Results showed that during spring season, hybrid P-33M15 performed well at sowing date 5-February as compared to other hybrids and sowing dates during 2016 and 2017. During autumn season, hybrid P-30R50 performed well at sowing date 25-July as compared to other hybrids and sowing dates in both years. In conclusion, for obtaining higher production, spring season is better as compared to autumn for maize crop
The study reports feasibility to synthesis copper loaded ZnO nanoparticles using a green synthesis approach influenced by natural extracts from waste maize materials is explored. Different methods were used to investigate the physicochemical characteristics of Cu-ZnO nanoparticles. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) studies were used to investigate the structural behavior of Cu-ZnO nanoparticles. XRD analysis shows that Cu-ZnO has a typical crystallite size of 23.5nm and a confirmed hexagonal structure. In the wavenumber range 400–600 cm-1 , FT-IR confirmed the presence of metallic elements in Cu-ZnO samples. Through the use of UV–vis spectroscopy, we were able to investigate the optical characteristics of Cu-ZnO. The samples' surface morphology was recorded by FESEM, and their elemental content was evaluated by EDX. This verifies the spherical shape of prepared samples with homogeneous size distributions across their structures. The nanostructured redox behaviour of electroactive Cu-ZnO has been investigated by cyclic voltammetry
The effects of water and nitrogen management on the oil and protein concentration of maize (Zea mays L.) grown in semiarid conditions are not well documented, although it is rather important for local consumers. The objectives of this study were, therefore, to determine the interaction between different nitrogen fertilizer rates and irrigation regimes on nitrogen uptake, and oil and protein content of maize grain. The importance of this study is to understand how the interaction of nitrogen and irrigation management affects the growth of maize and, thus, identify the best management practices to attain an optimal yield. A field experiment was conducted for 2 consecutive years in 2009 and 2010 using 5 nitrogen fertilizer rates, ranging from 100 to 300 kg N ha⁻¹, and 3 levels of irrigation management, ranging from 375 to 525 mm ha⁻¹, for a total of 15 treatments. The results showed that nitrogen accumulation in the maize plant linearly increased in applications up to 300 kg N ha⁻¹ even under deficit irrigation (375 mm ha⁻¹). For the application of 300 kg N ha⁻¹ under optimum irrigation (525 mm ha⁻¹), nitrogen accumulation in the plant's aboveground canopy was significantly increased (e.g., 145.7 and 144.3 kg ha⁻¹ during 2009 and 2010, respectively) as compared to smaller N application rates. The combined nitrogen and irrigation regimes of 300 kg N ha⁻¹ with 525 mm of irrigation resulted in the numerically maximum grain oil concentration, that is, 62 and 65 g kg⁻¹ during 2009 and 2010, respectively, and protein concentration in grains, that is, 116 and 120 g kg⁻¹ during 2009 and 2010, respectively. The regression analyses showed that the protein and oil concentrations of the grain are significantly and positively correlated with total nitrogen uptake. The nitrogen concentration in maize is driven by irrigation water and nitrogen fertilizer rates. Therefore, irrigation water and nitrogen fertilizers are the major inputs for not only improving maize grain yield but also maize grain quality.
The availability of water and nitrogen (N) to maize during its flowering stage affects the growth of individual kernels. The present study reports the variability of maize kernel dry weight under different levels of water and N applications. Two consecutive-year experiments were conducted during 2009 and during 2010 to study the interaction between three irrigation regimes and five N application rates on weekly maize kernel growth. Logistic and regression equations were fitted to kernel moisture content and kernel dry weight as a function of thermal time (TT) during critical crop stages. Kernel moisture content and growth rate increased non-linearly from 1 week after silking to physiological maturity. By applying logistic function we were able to improve simulation of kernel moisture content and daily increases in kernel dry weight. The logistic curve showed kernel moisture contents linearly correlated with kernel dry weight. Similarly, regression analyses of kernel dry weight showed a significant positive correlation with kernel moisture content for the 2009 (R2 = 0.86 NRMSE = 23%) and 2010 growing seasons (R2 = 0.92; NRMSE = 19%). Therefore, the logistics curves derived from the observed data may be helpful for predicting daily kernel growth for the semi-arid conditions. The results showed that the optimal N rate for maximum kernel dry weight was 250 kg ha−1 under 525 mm delta of water application ha−1. This rate might be considered in formulating good agricultural practices for optimum maize kernel growth in the semi-arid regions. Thus, our results contribute to better understanding of best management practices of N fertilizer and irrigation water for optimum maize productivity under semiarid region.
Maize is sown during spring and autumn seasons in Pakistan; however, studies on inter-seasonal variability on maize productivity, agronomic and nitrogen use efficiencies (NUEs) are limited. Therefore optimization of nitrogen (N) rate and hybrids selection for each season is critical to harvest better yield in maize–maize cropping system. Two independent field experiments were conducted to optimize N rates for different hybrids to improve maize productivity and NUEs in spring and autumn seasons during 2016 and 2017. During spring season, three spring-hybrids (P-33M15, M-DK6525 and S-NK8441) and during autumn season, three autumn-hybrids (P-30R50, M-DK6714 and S-NK6621) were sown under five N levels i.e., 0, 80, 160, 240 and 320 kg ha−1. Maize yield and related traits, and NUEs were improved with each higher level of N application. Highest and lowest grain yield, agronomic and economic NUEs were recorded at 320 kg N ha−1 and without N application, respectively in both seasons. Likewise, highest grain yield and NUEs were observed by spring-hybrid P-33M15 and autumn-hybrid P-30R50, while lowest were obtained by spring hybrid S-NK8441 and autumn hybrid S-NK6621 during both years. Nonetheless, maximum net income and benefit: cost ratio was observed by spring-hybrid P-33M15 and autumn hybrid P-30R50 at higher N level (320 kg ha−1) and maize cultivation without N was not profitable in both seasons. Maize cultivation with N application at 320 kg ha−1 seemed a viable option to get maximum productivity, economic returns and NUEs of maize–maize cropping system in irrigated arid environment of southern Punjab, Pakistan and might be for other areas having similar environmental conditions.
Human mineral malnutrition or hidden hunger is considered a global challenge, affecting a large proportion of the world’s population. The reduction in the mineral content of edible plant products is frequently found in cultivars bred for higher yields, and is probably increased by intensive agricultural practices. The filling of grain with macro and micronutrients is partly the result of a direct allocation from root uptake and remobilization from vegetative tissues. The aim of this bibliographic review is to focus on recent knowledge obtained from ionomic analysis of plant tissues in order to build a global appraisal of the potential remobilization of all macro and micronutrients, and especially those from leaves. Nitrogen is always remobilized from leaves of all plant species, although with different efficiencies, while nutrients such as K, S, P, Mg, Cu, Mo, Fe and Zn can be mobilized to a certain extent when plants are facing deficiencies. On the opposite, there is few evidence for leaf mobilization of Ca, Mn, Ni and B. Mechanisms related to the remobilization process (remobilization of mineral forms from vacuolar and organic compounds associated with senescence, respectively) are also discussed in the context of drought, an abiotic stress that is thought to increase and known to modulate the ionic composition of grain in crops.
To evaluate the physiological responses of wheat to zinc (Zn) fertilizer application under drought stress, pot, and field experiments were conducted on wheat plants grown under different soil moistures and treated with soil and foliar Zn applications. Photosynthetic characteristics, antioxidant content, Zn element concentration, and the transcription level of genes involved in antioxidant biosynthesis were analyzed. Zn application increased SPAD and Fv/Fm of wheat flag leaves, while decreased lipid peroxidation levels and H2O2 content. Zn application increased the antioxidant content (ascorbate, reduced glutathione, total phenolic, and total flavonoid) of wheat flag leaves, and enhanced the relative expression levels of two antioxidant enzyme genes, four ascorbate–glutathione cycle genes, and two flavonoid biosynthesis pathway genes under drought stress. Soil Zn application increased grain yield and Zn concentration by 10.5 and 15.8%, 22.6 and 9.7%, and 28.2 and 32.8% under adequate water supply, moderate drought, and severe drought, respectively. Furthermore, foliar application of Zn in the field increased grain yield and grain Zn concentration under both adequate water supply and rain-fed conditions. Zn plays a role in alleviating wheat plant drought stress by Zn-mediated increase in photosynthesis pigment and active oxygen scavenging substances, and reduction in lipid peroxidation. Furthermore, Zn fertilizer could regulate multiple antioxidant defense systems at the transcriptional level in response to drought.
In order to alleviate the drought adversities on maize biomass accumulation and radiation use efficiency, a field study was planned during 2009 and 2010 under drought stress levels of D1 = well-watered, D2 = drought stress at blister stage, D3 = drought stress at blister and dough stages; and integrated nutrition levels, N0 = control, N1 = NPK, 125-60-62 kg ha-1, N2 = NPK, 125-60-62 kg ha-1 + FYM at 10 t ha-1, N3 = NPK, 125-60-62 kg ha-1 + FYM at 15 t ha-1, N4 = NPK, 250-120-125 kg ha-1, N5 = NPK, 250-120-125 kg ha-1 + FYM at 10 t ha-1, N6 = NPK, 250-120-125 kg ha-1 + FYM at 15 t ha-1. Drought stress imposed a significant decline in growth traits, interception of photosynthetically active radiation (PAR), radiation use efficiency and finally biomass production. The highest leaf area index, leaf area duration, crop growth rate, net assimilation rate, interception of PAR and dry matter accumulation was recorded with NPK rate of 250-120-125 kg ha-1 with FYM of 15 t ha-1. Alone application of inorganic NPK had poor response in terms maximum light interception and dry biomass production. Fraction of intercepted radiation was significantly improved by integrated nutrient management under well-watered as well as drought stress conditions. A substantial decrease in total dry matter and grain yield basis radiation use efficiency was recorded from higher to lower plant nutrition rates, as the highest value of radiation use efficiency was found with treated plants of 250-120-125 kg NPK ha-1 + FYM at 15 t ha-1. Therefore, it is suggested that radiation use efficiency could be enhanced with adequate integrated NPK management along with farm yard manure.
Water is about to become increasingly limited for crop production, which jeopardizes the whole maize sector. Potassium (K) nutrition has been proposed to mitigate water deficit in plants, but field-scale studies involving grain yield components are scarce. In this study, we aimed at analyzing the effect of K nutrition on grain yield, vegetative growth and physiological parameters of maize subjected to water deficit. The effect of K nutrition on water use efficiency was also calculated at the whole-crop level (WUE) and through leaf gas exchange measurements (WUEi). A large-scale field experiment was designed, combining three levels of K fertilization (low, normal and high K) and two water supply scenarios (normal and 30% deficit based on a water balance model). Water deficit induced a strong decrease in leaf area, which was essentially due to a lower leaf elongation rate. The grain yield of the water-stressed plants was 25% lower than that of the well-irrigated ones. Grain yield was even worse when K deficiency was superimposed on water deficit, with a specific effect of K on grain filling. The optimal K fertilization helped the plants mitigate the effect of water deficit, through a better WUE (+ 30%), which was related to lower leaf evapotranspiration (ET). Moreover, under water deficit, leaf rolling was more pronounced when K was added, which also prevented water losses. Leaf water potential measurements suggested that the isohydric behaviour (maintenance of close stomata during water stress) of the maize was made possible thanks to K fertilization. When calculated at field scale, ET was higher with K fertilization, due to its positive effect on leaf area, in spite of a better stomata control and better WUE. We concluded that K addition, in K deficient soils, can help maize to cope with droughts and could be used as a new management option.
Most of the maize growing districts, constituting significantly in maize area of the six states (Bihar, Madhya Pradesh, Punjab, Orissa, Rajasthan and Uttar Pradesh) under study domain, experienced very low growth in maize yield and also harvest less than the national average yield. However, Bihar came out with the only state, which performed well registering high growth rate in maize yield along with higher level of its yield. Punjab followed next to Bihar with nearly 76 percent of the maize area recording higher yield but with slow growth. With respect to the stability of the growth of maize yield, most of the districts were found to be unstable. This may be attributed to the high variability in maize area of these states. During early seventies, the expansion in maize area declined considerably and remained virtually unchanged for the next two decades. Speedy spread of improved cultivars and crop management practices helped the continuous growth of average maize yield despite the sharp decline in the maize area. During nineties a significant shift occurred in maize production as the winter maize cultivation expanded rapidly, particularly in the state of Bihar. It is hoped that the new paradigm shift in the seed and price policy of cereals and the enhanced support to the exports of cereals would bring significant expansion in the maize area and over all maize industry.
Water and nitrogen are the most important factors, play their role in better growth and yield of maize. To find out effective use of resources a field experiment was conducted to study the effect of irrigation regimes and nitrogen rates on growth and yield of maize hybrid at Agronomic Research Area, University of Agriculture, Faisalabad, during 2009. The experiment was laid out in Randomized Complete Block Design with split plot arrangement having three replications. Three irrigation regime i.e., I1 (eight irrigation), I2 (six irrigation, two missed at vegetative stage) and I3 (seven one missed at grain filling stage) were kept in main plots and four rates of nitrogen; N1 (150 kg ha-1), N2 (200 kg ha-1), N3 (250 kg ha-1) and N4 (300 kg ha-1) were randomized in sub plots. Results showed that maximum leaf area index (4.92), number of grains per cob (490), grain yield (8.49 t ha-1) and harvest index (47.73%) were achieved in N3 treatment with I1 irrigation regime while the highest biological yield (17.97 t ha-1) was recorded in N4 treatment with the I1 irrigation regimes. The minimum1000-grains weight (314 g), biological yield (12.48 t ha-1) and grain yield (4.67 t ha-1) were recorded in the combination of I2 and N1 treatments. Water stress at six and twelve leaves stage simultaneously decreased grain yield 30% while water stress at grain filling stage decreased 20% yield.
Infrared thermal radiometers (IRTs) are an affordable tool for researchers to monitor canopy temperature. In this maize experiment, six treatments of regulated deficit irrigation levels were evaluated. The main objective was to evaluate these six treatments in terms of six indices (three previously proposed and three introduced in this study) used to quantify water stress. Three are point-in-time indices where one daily reading is assumed representative of the day (Crop Water Stress Index – CWSI, Degrees Above Non-Stressed – DANS, Degrees Above Canopy Threshold – DACT) and three integrate the cumulative impact of water stress over time (Time Temperature Threshold – TTT, Integrated Degrees Above Non-Stressed – IDANS, Integrated Degrees Above Canopy Threshold – IDACT). Canopy temperature was highly correlated with leaf water potential (R2 = 0.895). To avoid potential bias, the lowest observation from the non-stressed treatment was chosen as the baseline for DANS and IDANS indices. Early afternoon temperatures showed the most divergence and thus this is the ideal time to obtain spot index values. Canopy temperatures and stress indices were responsive to evapotranspiration-based irrigation treatments. DANS and DACT were highly correlated with CWSI above the corn threshold 28 °C used in the TTT method, and all indices showed linear relationship with soil water deficit at high temperatures. Recommendations are given to consider soils with high water-holding capacity when choosing a site for non-stressed reference crops used in the DANS method. The DACT may be the most convenient index, as all it requires is a single canopy temperature measurement yet has strong relationships with other indices and crop water measurements.
Abstract
A field experiment was conducted during spring 2011 at Agronomic Research Area, University of
Agriculture, Faisalabad, Pakistan to evaluate the comparative efficacy of Zn uptake and grain yield
in three maize hybrids namely Pioneer-32F 10, Monsanto-6525 and Hycorn-8288 through the application
of Zn in the form of ZnSO4. The ZnSO4 treatments comprised; soil application at the time
of sowing @ 12 kg∙ha−1 (Zn1), foliar application at vegetative stage (9 leaf stage) @ 1% ZnSO4 solution
(Zn2) and foliar application at reproductive stage (anthesis) @ 1% ZnSO4 solution (Zn3) and
one treatment was kept as a control, where zinc was not applied (Zn0). The experimental results
showed substantial difference in all physiological and yield parameters except plant height and
stem diameter. Statistically maximum grain yield (8.76 t∙ha−1) was obtained with foliar spray of
ZnSO4 at 9 leaf stage (Zn2) in case of Monsanto-6525. As regard to quality parameters, Pioneer-32F
10 and Hycorn-8288 accumulated more zinc contents in grains but Monsanto-6525 attained more
zinc concentration in straw. Foliar spray of ZnSO4 at 9 leaf stage produced 19.42% more zinc contents
in grains as compared to other ZnSO4 treatments. Foliar spray of ZnSO4 at 9 leaf stage in
Monsanto-6525 hybrid produced higher grain yield.
Keywords
Grain Yield, Hybrids, Maize (Zea mays L.), ZnSO4
Effects of different levels of N and intra-row plant spacing on yield and yield components of maize cv. "Golden"
was studied at the University of Agriculture, Faisalabad during 1998. The nitrogen levels comprised 0-100-140 and
180 kg ha" while the intra-row plant spacing were 10, 20 and 30 cm. Both nitrogen and plant spacing had a
significant effect on plant height, number of grains per cob, 1000-grain weight and harvest index. The maximum
grain yield (5.7 t ha") was produced when plant spacing was kept 'as 20 cm and N was applied at the rate of
180 kg ha".
In a long-term experiment on continuous maize set up by Béla Győrffy in 1959, changes in biotic and abiotic environmental factors were studied over time. The long-term effects and stability of the cropping systems, the year effects and the genotype × environment interactions were analysed. The original aim of the experiment was to determine whether the NPK nutrients in farmyard manure could be replaced partially or entirely by inorganic NPK fertiliser. In the present experiment the effect of farmyard manure, mineral fertiliser and the year effect on yield and yield stability were studied for four years (2005–2008). Various levels of farmyard manure and mineral fertiliser induced significant changes in the yield, harvest index, thousand-kernel mass, grain number per ear and grain protein content.
The effect of adding zinc sulphate (ZnSO4) to maize (Zea mays L.) growing on calcareous, Zn deficient soils in the North West Frontier Province of Pakistan was assessed in vitro, on-station and in on-farm trials. The zinc sulphate was added either as a powder to the soil or by soaking seeds for 16 h in dilute solutions prior to sowing. For the first time in maize, we separated the benefits of priming simply with water from those provided by added zinc.In four trials, the soil application of 2.75 kg Zn ha−1 significantly increased mean maize grain yield by 720 kg ha−1 (25%) total dry matter, number of cobs and cob weight. Adding 5.50 kg Zn ha−1 was the same as adding 2.75 kg Zn ha−1 for TDM and cob yield but worse for cob number and grain yield.Preliminary experiments established that maize seeds could be primed safely and effectively for 16 h with 1% Zn solutions. Such priming increased seed Zn content initially from 15 mg kg−1 to 560 mg kg−1 but this was reduced to 220 mg kg−1 by rinsing the seed surface with distilled water. Non-rinsed seeds were used in all field trials. Seedlings from seeds primed with either 1% or 2% Zn were significantly heavier and taller than seedlings from non-primed seeds. The Zn concentration of seedlings was unaffected by priming with water alone but was increased significantly by both Zn priming treatments. The amount of Zn per plant was further increased because priming and Zn supply produced bigger plants.In seven further trials, mean grain yield was significantly increased from 3.0 t ha−1 in crops from non-primed seed to 3.4 t ha−1 (14%) in crops from seeds primed with water alone and to 3.8 t ha−1 (27%, a similar response to that following soil application) using seeds primed with 1% Zn. Hence, the contribution of water alone and zinc contributed about equally to the overall increase. Total dry matter, stover dry matter, cob yield, individual cob weight, grain number per cob, cob number and 1000-grain weight showed similar responses to that of mean grain yield. Plant population density and shelling percentage were unaffected by either treatment. Grain Zn concentration was 15.4 mg kg−1 in a non-primed crop and was significantly higher in a crop grown from seeds primed with water (16.5 mg kg−1) and with 1% Zn (18.3 mg kg−1). The apparent recovery of added Zn in the grain was much higher for seed priming (at around 80%) than the less than 1% for soil fertilisation.Monetary returns to use of ZnSO4 were high, with a benefit to cost ratio for soil application of 15. However, the ratio was much higher, at 236, when a 1% Zn solution was used to prime seeds before sowing. This was due to the small amounts of ZnSO4 used per hectare and hence low cost. Since priming maize seeds with water increased yield by 14% at no extra cost and adding small amounts of ZnSO4 to the priming water doubled that yield gain, priming with 1% Zn represents an attractive option for resource-poor maize farmers in Zn-deficient areas in Pakistan and elsewhere.
Understanding farmers' production constraints and preferences is important in maize breeding, especially underlying successful adoption of improved varieties and their production packages. This study was conducted to assess the present importance, and productivity constraints of maize in the mid-altitude, sub-humid agro-ecology of Western Ethiopia. Data was collected through a semi-structured questionnaire and focus group discussions, using 240 randomly selected respondent farmers, in 12 sub-districts, within three administrative zones. Maize was ranked number one as both food and cash crop by 82.9% of respondents. Most farmers (59%) use hybrids, while 24% grow landrace varieties. Unavailability of improved seed and lack of production inputs were the two major constraints reducing maize productivity, as reported by 62 and 60% of respondents, respectively. A high proportion of respondents (80%) indicated that, unpredictable grain prices are the major market constraint as 97% of the respondents sell their maize crop in the local market. Northern corn leaf blight (NCLB) was reported to be important by 46% of respondents. Breeding for improved disease resistance and grain yield, enhancing the availability of crop input and stabilizing market price during harvest time are the most important strategies to increase maize production by small-scale farmers in Western Ethiopia.
A pot experiment was conducted to screen 60 maize accessions for water stress tolerance. In preliminary experiment, 60 maize accessions were grown at four moisture levels (100%, 80%, 60% and 40% of field capacity) and evaluated on the basis of survival rate. About 10 maize accessions namely NC-9, M-14, B-42, NC-3, N18, W187R, NC-42, NC-8 and A50-2 with highest survival rate at low moisture level (40% of FC) were selected as water stress tolerant and other 10 maize accessions namely T-7, WFTMS, B-34, NC-7, N48-1, OH54-3A, T-5, UMZ, NC-4 and USSR with lowest survival rate at mild stress (moisture level 80% of FC) were selected as susceptible to water stress. In the 2nd experiment, these selected maize accessions were further evaluated on the basis of survival rate, relative cell membrane injury (RCI %age), and stomatal conductance. Broad sense heritability for these traits was also estimated and it was found that RCI% could be used as main selection criterion for drought tolerance in maize. Furthermore, on the basis of this selection criterion, NC-9 was found as highly water stress tolerant, while T-7 recognized as drought susceptible.
Seasonal variation in three plant factors and in evaporation rates were determined for dryland cotton and grain sorghum in central Texas. Plant factors measured were fractional ground cover, dry matter production, and leaf area index (LAI). When an adequate supply of soil water was available in the rhizosphere, plant factors influenced evaporation rates during most of the first half of the groiwng season until a “threshold” canopy LAI was obtained. A threshold canopy LAI is defined as the minumum LAI necessary to obtain 90% of potential evaporation (E o ) from row crops when the soil evaporation (E s ) is small. The threshold LAI was approximately 2.7 for both crops studied. After the threshold canopy LAI was obtained, evaporation was practically independent of plant factors and equal to E o , as estimated from daily net radiation, until soil water movement to plant roots began to limit evaporation.
E s strongly influenced the actual evaporation rates obtained when plant canopy LAIs were below 2.7, To evaluate the influence of plant factors on the resulting plant evaporation (E p ) independent of E s , it was necessary to attempt a rational separation of E s , and E p . E s was assumed to be equal to the net radiation equivalent of evaporation below the plant canopy when the soil surface was wet. After the soil surface dried sufficiently to limit water movement to the surface, E s was estimated from the measured soil water content near the surface. E p was estimated using the measured evaporation and E s . The ratio E p /E o was found to be related to the LAI according to the equation
E p /E o = −0.21 + 0.70 LAI 1/2 , 0.1 ≤ LAI ≤ 2.7
This nonlinear relation indicates that E p is larger per unit of leaf area for smaller plants than for larger plants with LAIs approaching 2.7. Sensible heat originating over partially dry surface soil between plant rows was a significant source of the total energy contributing to E p
The physiological stage of growth did not greatly influence the amount of energy used in evaporation as grain sorghum plants approached maturity when an adequate supply of soil water was available.
The results imply a possibility for improving water‐use efficiency of dryland crops by using higher plant populations and closer row spacings to decrease E s if the soil water supply and seasonal rainfall is adequate to produce an economic yield.
Synopsis
Moisture stress prior to silking reduced grain yield by 25%, moisture stress at silking reduced grain yield by 50% and moisture stress after silking reduced grain yield by 21%. The interactions between different growth stages were not statistically significant.
A field study was carried out from 1995 to 1997 in order to determine the effect of irrigation and water stress imposed at different development stages on vegetative growth, grain yield and other yield components of corn (Zea mays L.). The field trials were conducted on a silty loam Entisol soil, with Pioneer 3377 corn hybrid. A randomised complete block design with three replications was used. Four known growth stages of the plant were considered and a total of 16 (including rain fed) irrigation treatments were applied. The effect of irrigation or water stress at any stage of development on plant height, leaf area index, grain yield per hectare, as well number of ears per plant, grain yield per cob and 1000 kernels weight, were evaluated. Results of this 3-year study show that all vegetative and yield parameters were significantly affected by water shortage in the soil profile due to omitted irrigation during the sensitive tasselling and cob formation stages. Water stress occurring during vegetative and tasselling stages reduced plant height, as well as leaf area development. Short-duration water deficits during the rapid vegetative growth period caused 28–32% loss of final dry matter weight. Highest yields were observed in the fully irrigated control (VTCM) and the treatment which allowed water stress during the vegetative growth stage (TCM). Even a single irrigation omission during one of the sensitive growth stages, caused up to 40% grain yield losses during dry years such as 1996. Much greater losses of 66–93% could be expected as a result of prolonged water stress during tasselling and ear formation stages. Seasonal irrigation water amounts required for non-stressed production varied by year from 390 to 575mm. Yield response factor (ky) values (unitless parameter) relating yield loss to water deficits) obtained for the first, second and third experimental years were determined to be 1.22, 1.36 and 0.81, respectively.
Excess Soil Moisture (ESM) in varying forms posses serious threat to overall production and productivity of maize in Asian region particularly in South East Asia and India. Maize responds differently to ESM conditions at different stages of its life cycle. Further a particular genotype shows differential behaviour to varying levels of waterlogging stress. Seedling stage being very susceptible to excess soil water as wa s observed in cup screening experiment. Out of 15 genotypes (parents and their crosses made in half diallel fashion), sussceptible genotypes performed poorly and did not reach two leaf stage or even germinated. Most of the genotypes were grouped into first three classes out of the total pre assigned five classes on the basis of their response to waterlogging, reflecting the degree of susceptibility at seedling stage in maize. In normal cup screening trial all the genotypes performed normally. At knee height stage, responses to ESM in different genotypes showed fair correspondence with the responses at seedling. Flooding at knee height stage of th e crop growth resulted in immediate wilting of plants starting from the base of the plant and subsequent lodging of most of the plants. In leaves, wilting started from the tip and proceeded towards the base of the leaf. In tolerant genotypes there was profuse appearance of adventitious roots on even up to five nodes in some cases. In most of the genotypes Anthesis Silking Interval (ASI) got widened even more than eight days in some cases was recorded, which subsequently resulted in barrenness of plants and reduction of overall yield. Plant height and ear height was severely affected and in almost all genotypes there was reduction in plant height due to flooding treatment. Physiological traits also got affected due to flooding. There was decrease in transpiration rate and Photosynthetically Active Radiation (PAR) got increases in most of the genotypes due to flooding. SPAD values (relative greenness) of the plants got reduced. There was no sinificant change in leaf temperature in most of the cases. Drastic reduction in most of the genotypes was observed but still Pop 3121 and Pop 3118 showed fairly better yields under waterlogged conditions. ASI and PAR showed negative correlation with yield while as nodes bearing adventitious roots showed positive correlation with yield under water logged conditions. In most of the genotypes there was fading of leaf colour immediately after flooding treatment as reflected by their corresponding SPAD values. Tarun 83 showed immediate epinastic effects in the upper leaves on flooding
An estimated 80% of the maize crop suffers periodic yield reduction due
to drought stress. Drought at flowering and grain filling period may cause
losses of 40-90%. Predicated on the argument that climate change
resulted from changes in climatic elements such as rainfall, this study
aimed at investigating the relationship between rainfall, among other
factors, and maize crop production in Kaduna state over a period of 15
years. Time series data on aggregate maize production, fertilizer use,
total area under cultivation with the maize crop and annual rainfall in
Kaduna State for the period 1990-2005 were collected and analysed
using multiple regression technique. Findings of the study showed that
annual rainfall contributes significantly and positively to maize production
in the study area inspite of climate change, indicating that climate change
has not significantly altered the pattern of rainfall in the study area in such
a way as to affect maize production negatively.
Early water stress recognition is of great relevance in precision plant breeding and production. Hyperspectral imaging sensors can be a valuable tool for early stress detection with high spatio-temporal resolution. They gather large, high dimensional data cubes posing a significant challenge to data analysis. Classical supervised learning algorithms often fail in applied plant sciences due to their need of labelled datasets, which are difficult to obtain. Therefore, new approaches for unsupervised learning of relevant patterns are needed. We apply for the first time a recent matrix factorisation technique, simplex volume maximisation (SiVM), to hyperspectral data. It is an unsupervised classification approach, optimised for fast computation of massive datasets. It allows calculation of how similar each spectrum is to observed typical spectra. This provides the means to express how likely it is that one plant is suffering from stress. The method was tested for drought stress, applied to potted barley plants in a controlled rain-out shelter experiment and to agricultural corn plots subjected to a two factorial field setup altering water and nutrient availability. Both experiments were conducted on the canopy level. SiVM was significantly better than using a combination of established vegetation indices. In the corn plots, SiVM clearly separated the different treatments, even though the effects on leaf and canopy traits were subtle.
Climate is changing and, as a consequence, some areas that are climatically suitable for date palm (Phoenix dactylifera L.) cultivation at the present time will become unsuitable in the future. In contrast, some areas that are unsuitable under the current climate will become suitable in the future. Consequently, countries that are dependent on date fruit export will experience economic decline, while other countries' economies could improve. Knowledge of the likely potential distribution of this economically important crop under current and future climate scenarios will be useful in planning better strategies to manage such issues. This study used CLIMEX to estimate potential date palm distribution under current and future climate models by using one emission scenario (A2) with two different global climate models (GCMs), CSIRO-Mk3.0 (CS) and MIROC-H (MR). The results indicate that in North Africa, many areas with a suitable climate for this species are projected to become climatically unsuitable by 2100. In North and South America, locations such as south-eastern Bolivia and northern Venezuela will become climatically more suitable. By 2070, Saudi Arabia, Iraq and western Iran are projected to have a reduction in climate suitability. The results indicate that cold and dry stresses will play an important role in date palm distribution in the future. These results can inform strategic planning by government and agricultural organizations by identifying new areas in which to cultivate this economically important crop in the future and those areas that will need greater attention due to becoming marginal regions for continued date palm cultivation.
Zinc deficiency is a well-documented problem in food crops, causing decreased crop yields and nutritional quality. Generally,
the regions in the world with Zn-deficient soils are also characterized by widespread Zn deficiency in humans. Recent estimates
indicate that nearly half of world population suffers from Zn deficiency. Cereal crops play an important role in satisfying
daily calorie intake in developing world, but they are inherently very low in Zn concentrations in grain, particularly when
grown on Zn-deficient soils. The reliance on cereal-based diets may induce Zn deficiency-related health problems in humans,
such as impairments in physical development, immune system and brain function. Among the strategies being discussed as major
solution to Zn deficiency, plant breeding strategy (e.g., genetic biofortification) appears to be a most sustainable and cost-effective
approach useful in improving Zn concentrations in grain. The breeding approach is, however, a long-term process requiring
a substantial effort and resources. A successful breeding program for biofortifying food crops with Zn is very much dependent
on the size of plant-available Zn pools in soil. In most parts of the cereal-growing areas, soils have, however, a variety
of chemical and physical problems that significantly reduce availability of Zn to plant roots. Hence, the genetic capacity
of the newly developed (biofortified) cultivars to absorb sufficient amount of Zn from soil and accumulate it in the grain
may not be expressed to the full extent. It is, therefore, essential to have a short-term approach to improve Zn concentration
in cereal grains. Application of Zn fertilizers or Zn-enriched NPK fertilizers (e.g., agronomic biofortification) offers a
rapid solution to the problem, and represents useful complementary approach to on-going breeding programs. There is increasing
evidence showing that foliar or combined soil+foliar application of Zn fertilizers under field conditions are highly effective
and very practical way to maximize uptake and accumulation of Zn in whole wheat grain, raising concentration up to 60mg Zn
kg−1. Zinc-enriched grains are also of great importance for crop productivity resulting in better seedling vigor, denser stands
and higher stress tolerance on potentially Zn-deficient soils. Agronomic biofortification strategy appears to be essential
in keeping sufficient amount of available Zn in soil solution and maintaining adequate Zn transport to the seeds during reproductive
growth stage. Finally, agronomic biofortification is required for optimizing and ensuring the success of genetic biofortification
of cereal grains with Zn. In case of greater bioavailability of the grain Zn derived from foliar applications than from soil,
agronomic biofortification would be a very attractive and useful strategy in solving Zn deficiency-related health problems
globally and effectively.
The threat posed by invasive species, in particular weeds, to biodiversity may be exacerbated by climate change. Lantana camara L. (lantana) is a woody shrub that is highly invasive in many countries of the world. It has a profound economic and environmental impact worldwide, including Australia. Knowledge of the likely potential distribution of this invasive species under current and future climate will be useful in planning better strategies to manage the invasion. A process-oriented niche model of L. camara was developed using CLIMEX to estimate its potential distribution under current and future climate scenarios. The model was calibrated using data from several knowledge domains, including phenological observations and geographic distribution records. The potential distribution of lantana under historical climate exceeded the current distribution in some areas of the world, notably Africa and Asia. Under future scenarios, the climatically suitable areas for L. camara globally were projected to contract. However, some areas were identified in North Africa, Europe and Australia that may become climatically suitable under future climates. In South Africa and China, its potential distribution could expand further inland. These results can inform strategic planning by biosecurity agencies, identifying areas to target for eradication or containment. Distribution maps of risk of potential invasion can be useful tools in public awareness campaigns, especially in countries that have been identified as becoming climatically suitable for L. camara under the future climate scenarios.
For many years, U.S. policy initiatives and incentives have favored the production of ethanol from corn. The goals have been to increase corn prices and farmer income, enhance rural employment through encouragement of value-added businesses, increase energy security, and produce additives and/or fuels capable of reducing tailpipe pollutants and greenhouse gases. The Energy Policy Act of 2005 established annual goals via a renewable fuels standard that would have increased production of ethanol and biodiesel to 7.5 billion gallons by 2012. That bill was superseded by the Energy Independence and Security of Act of 2007, which increased usage targets and specified performance standards for ethanol and other biofuels. The 2008 Farm Bill identified incentive payments for ethanol produced in various ways. The effects of these three laws have been magnified by rising crude oil prices, which helped maintain profits for corn dry-grind ethanol plants. This paper discusses environmental effects of corn ethanol production and use, energy balances of corn ethanol versus gasoline, subsidies for corn ethanol and gasoline, impacts of ethanol production on farmer decisionmaking, and effects of corn ethanol on food prices.
An improved understanding of soil fertility variability and farmers’ resource use strategies is required for targeting soil fertility improving technologies to different niches within farms. We measured the variability of soil fertility with distance from homesteads on smallholder farms of different socio-economic groups on two soil types, a granite sand and a red clay, in Murewa, northeast Zimbabwe. Soil organic matter, available P and CEC decreased with distance from homestead on most farms. Soil available P was particularly responsive to management, irrespective of soil type, as it was more concentrated on the plots closest to homesteads on wealthy farms (8–13mgkg−1), compared with plots further from homesteads and all plots on poor farms (2–6mgkg−1). There was a large gap in amounts of mineral fertilizers used by the wealthiest farmers (>100kg N and >15kg P per farm; 39kgNha−1 and 7kgPha−1) and the poorest farmers (13kgPha−1), but decreased to 10–20N and 6–9kg P per plot (
This book, containing 17 chapters, is intended to be a guide to understanding maize kernel development. The knowledge and insight in this book are the culmination of centuries of genetic and biochemical work directed at increasing the yield and nutritional value of maize. Topics covered include kernel evolution (from teosinte to maize); gametophyte interactions establishing kernel development; endosperm development and cell specialization; kernel mutants; the basal endosperm transfer layer; aleurone; embryo development; embryo-endosperm-sporophyte interactions in seeds; aneuploidy and ploidy in the endosperm; cell cycle and cell size regulation during maize seed development; central metabolism and its spatial heterogeneity in maize endosperm; starch biosynthesis in endosperm; kernel oil content; seed storage proteins; determinants of kernel sink strength; natural variations in maize kernel size; and effects of drought stress on kernel set.
Salt stress is an acute threat to plants, especially to field crops in irrigated and saline areas of the world. Rice is the second staple crop of the world after wheat, and its production is strongly affected by salinity. Therefore, to ensure food security, it is crucial to manage salt stress for sustainable rice production under saline conditions. Plant physiological, biochemical, and genetic characteristics play an important role in the adaptation of rice to saline environments. Further, the knowledge of the relationship among these characteristics is necessary to manage the salt stress and achieve optimal rice production. This review focuses on the response of rice to salinity stress; its physiological, biochemical, and genetic changes; its adaptation to saline soils through osmoregulation, ion homeostasis, apoplastic acidification, synthesis of antioxidants, genes, and hormonal regulations; and synthesis of stress-responsive proteins. Future research is needed on management strategies such as breeding for salt-tolerant cultivars, application of molecular markers to select salt-tolerant germplasm, potential of genetic transformation for salinity resistance, application of arbuscular mycorrhizal fungi, and plant growth-regulating rhizobacteria, nutrient management, and seed priming techniques for sustainable rice production in saline areas. In conclusion, salt stress affects metabolism and physiology of rice and reduces the agronomic yield. Therefore, development of salt-tolerant genotypes may be a prudent strategy to manage the salinity. Focused research on integration of different management options can lead to sustainable rice production in saline areas which may contribute significantly to global food security.
Climate resilient cropping systems are required to adapt to the increasing threats of climate change projected for Southern Africa and to better manage current climate variability. Conservation agriculture (CA) has been proposed among technologies that are climate-smart. For a cropping system to be labelled “climate-smart” it has to deliver three benefits: a) adapt to the effects of climate and be of increased resilience; b) mitigate climate effects by sequestering carbon (C) and reducing greenhouse gas emissions (GHG); and c) sustainably increase productivity and income. Research on smallholder farms from Southern Africa was analysed to assess if CA can deliver on the three principles of climate-smart agriculture. Results from Southern Africa showed that CA systems have a positive effect on adaptation and productivity, but its mitigation potential lags far behind expectations. CA systems maintain higher infiltration rates and conserve soil moisture, which helps to overcome seasonal dry-spells. Increased productivity and profitability were recorded although a lag period of 2–5 cropping seasons is common until yield benefits become significant. Immediate economic benefits such as reduced labour requirements in some systems will make CA more attractive in the short term to farmers who cannot afford to wait for several seasons until yield benefits accrue. The available data summarizing the effects of CA on soil organic C (SOC) and reductions in greenhouse gases, are often contradictory and depend a great deal on the agro-ecological environment and the available biomass for surface residue retention. There is an urgent need for more research to better quantify the mitigation effects, as the current data are scanty. Possible co-interventions such as improved intercropping/relay cropping systems, agroforestry and other tree-based systems may improve delivery of mitigation benefits and need further exploration.
Heat and drought stress frequently occur together, however their impact on plant growth and photosynthesis (PN ) is unclear. The frequency, duration and severity of heat and drought stress events are predicted to increase in the future, having severe implications for agricultural productivity and food security. To assess these impacts on plant gas exchange, physiology and morphology we grew drought tolerant and sensitive varieties of C3 sunflower (Helianthus annuus) and C4 maize (Zea mays) under conditions of elevated temperature for four weeks prior to the imposition of water deficit. The negative impact of temperature on PN was most apparent in sunflower. The drought tolerant sunflower retained ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) activity under heat stress to a greater extent than its drought sensitive counterpart. Maize exhibited no varietal difference in response to increased temperature. In contrast to previous studies, where a sudden rise in temperature induced an increase in stomatal conductance (Gs ), we observed no change or a reduction in Gs with elevated temperature, which alongside lower leaf area mitigated the impact of drought at the higher temperature. The drought tolerant sunflower and maize varieties exhibited greater investment in root-systems, allowing greater uptake of the available soil water. Elevated temperatures associated with heat-waves will have profound negative impacts on crop growth in both sunflower and maize, but the deleterious effect on PN was less apparent in the drought tolerant sunflower and both maize varieties. As C4 plants generally exhibit water use efficiency (WUE) and resistance to heat stress, selection on the basis of tolerance to heat and drought stress would be more beneficial to the yields of C3 crops cultivated in drought prone semi-arid regions.
Proceedings of the Third International Rice Genetics Symposium October 16-20, 1995.
Potential consequences of climate change on crop production can be studied using mechanistic crop simulation models. While a broad variety of maize simulation models exist, it is not known whether different models diverge on grain yield responses to changes in climatic factors, or whether they agree in their general trends related to phenology, growth and yield. With the goal of analyzing the sensitivity of simulated yields to changes in temperature and atmospheric carbon dioxide concentrations [CO2 ], we present the largest maize crop model inter-comparison to date, including 23 different models. These models were evaluated for four locations representing a wide range of maize production conditions in the world: Lusignan (France), Ames (USA), Rio Verde (Brazil) and Morogoro (Tanzania). While individual models differed considerably in absolute yield simulation at the four sites, an ensemble of a minimum number of models was able to simulate absolute yields accurately at the four sites even with low data for calibration, thus suggesting that using an ensemble of models has merit. Temperature increase had strong negative influence on modeled yield response of roughly -0.5 Mg.ha(-1) per °C. Doubling [CO2 ] from 360 to 720 μmol mol(-1) increased grain yield by 7.5% on average across models and the sites. That would therefore make temperature the main factor altering maize yields at the end of this Century. Furthermore, there was a large uncertainty in the yield response to [CO2 ] among models. Model responses to temperature and [CO2 ] did not differ whether models were simulated with low calibration information or, simulated with high level of calibration information. This article is protected by copyright. All rights reserved.
Improved soil-water management techniques have made irrigated corn (Zea mays L. ) yields of more than 12. 5 Mg ha** minus **1 possible in the southeastern USA. Data relating fertilizer rates and soil test indices to grain yield under intensive water management are needed to maximize fertilizer use efficiency. The objective of this study was to generate fertility index-yield response data from which critical levels of Mehlich 1 soil test P, K, and Mg could be calculated. Calculated critical Mehlich 1 soil test levels were 9, 45, and 33 mg kg** minus **1 for P, K, and Mg, respectively. Comparison of our results with current soil test rating categories and corresponding recommended fertilizer rates indicated that maximum corn yield was obtained with a P fertilizer rate which was 50 kg ha** minus **1 lower than the recommended rate.
A field experiment was conducted during growing season of 2007-2008 at Khorasan Agricultural and Natural Resource Research Center, Mashhad-Iran, to study dry matter accumulation and remobilization in grain sorghum genotypes under water stress and normal conditions. The main plots were allocated to two levels of moisture regimes, including water deficit after anthesis and normal condition (no water stress) and the subplots were disturbance photosynthesis with potassium iodide and non disturbance on current photosynthesis and three grain sorghum genotypes (Sepideh, M5 and M2 promising lines). The results showed that water stress significantly (p≤0.01) increased amounts of remobilized dry matter (ARDM), remobilization efficiency (REE), remobilization percentage (REP) by 11.21%, 32.37 % and 14.20%, respectively, compared with normal condition over all treatments. However it significantly (p≤0.05) decreased biological and grain yield. Disturbance in current photosynthesis caused 57.79 % and 21.20 % increase in remobilization percentage and remobilization efficiency compared to non disturbance status across all treatments. M5 genotype had the highest remobilization percentage and remobilization efficiency as compared with the two other genotypes in all experimental plots. The stepwise linear multiple regression indicated that grain yield would be properly predicted by biological yield and harvest index (R 2 =0.99, p≤0.01).
Soil tillage often results in a structurally unstable soil layer with an elevated inter-aggregate porosity that is gradually decreased by the interplay of capillary and rheological processes. We have previously proposed to describe the evolution of the pore-size distribution (PSD) with the Fokker–Planck equation (FPE). The coefficients of this equation quantify the drift, dispersion, and degradation processes acting upon the PSD. An analytical solution for the PSD is presented for the case where drift and degradation coefficients depend on time, and the dispersion coefficient is proportional to the drift coefficient. These coefficients can be estimated from independent measurements of the PSD or (surrogate) water retention data or from mechanistic models. In this paper, we illustrate the application of the pore-size evolution model for: (i) a generic drift coefficient, (ii) static water retention data for soils under different tillage regimes, and (iii) dynamic hydraulic data for a soil subject to a sequence of wetting and drying cycles. These applications show the viability of our approach to model pore-size evolution. However, the development and application of the model is hampered by a lack of definitive data on soil structural and hydraulic dynamics.
Field and container experiments were carried out in order to quantify root growth and dry matter partitioning of cauliflower under drought stress conditions. Drought stress did not influence allometric relationships between leaf and stem dry matter and shoot and tap root dry matter. Drought stress, however, had an impact on the sink strength of the curd, thereby curd growth was delayed and curd dry matter production was more seriously depressed by a limited water supply than total dry matter. Drought stress did not modify a linear relationship between shoot dry matter and total root length, however, the specific root length of cauliflower was lower under drought stress conditions leading to a higher dry matter deposition in the fine root fraction. Also the vertical increment of rooting depth per degree day almost doubled under drought stress conditions. An existing model for dry matter partitioning in cauliflower was adopted to include the effects of drought stress on dry matter partitioning to the curd. Therefore, the initial increase of the curd's sink strength was made dependent on the plants relative growth rate during the vernalisation period. Furthermore, a simple descriptive root growth model was adopted to include drought stress impact on root growth. For this purpose the increase of rooting depth per degree day and the specific root length were made dependent on the average soil water potential in the rooted soil profile. The modified model modules predicted dry matter partitioning and described the root length distribution of cauliflower sufficiently well using total dry matter production rate as input values.
Field trials were conducted in 1999 and 2000 in the northern Guinea savanna of Nigeria to evaluate the potential of several weed management practices to reduce early weed competition in maize. The treatments were different combinations of the herbicide mixture metolachlor + atrazine at 5 L ha−1, the cover crop velvetbean (Mucuna cochinchinensis), hoe weeding at 2, 4, and 6 weeks or at 4 and 8 weeks after planting (WAP) maize, maize density: high (60,000 plants ha−1), medium (40,000 plants ha−1), low (25,000 plants ha−1) and a farmer's control consisting of a single weeding at 4 WAP and low maize density. Results showed that maize grain yield was significantly higher in the treatment in which either the herbicide mixture or velvetbean was combined with 40,000 maize plants ha−1 and weeded thrice. The lowest maize grain yield was obtained with the farmer's control. Weed dry matter was 60% more in the farmer's control than in velvetbean combined with 40,000 maize plants ha−1 and weeded three times. The farmer's control was higher in weed species diversity with Setaria pallide-fusca, Vernonia galamensis, and Boerhavia erecta as the dominant species. Sporobolus pyramidalis and Thelepogon elegans were the dominant weeds in the herbicide treatment and velvetbean plots, respectively. Herbicide or velvetbean in combination with medium maize density and weeding three times (2, 4, and 6 WAP) is recommended for weed management in the northern Guinea savanna.
The impacts of climate change on agriculture may add significantly to the development challenges of ensuring food security and reducing poverty. We show the possible impacts on maize production in Africa and Latin America to 2055, using high-resolution methods to generate characteristic daily weather data for driving a detailed simulation model of the maize crop. Although the results indicate an overall reduction of only 10% in maize production to 2055, equivalent to losses of $2 billion per year, the aggregate results hide enormous variability: areas can be identified where maize yields may change substantially. Climate change urgently needs to be assessed at the level of the household, so that poor and vulnerable people dependent on agriculture can be appropriately targeted in research and development activities whose object is poverty alleviation.
The decrease in crop yields at increasing distances from the homesteads within smallholder farms of Sub-Saharan Africa (SSA) is normally ascribed to the existence of within-farm soil fertility gradients. Field observations also suggest that a large part of such variability is concomitantly caused by poor agronomy. To understand the interaction between soil fertility (S factors) and management decisions (M factors) affecting crop variability, we combined field research conducted in western Kenya (Vihiga, Kakamega and Teso districts; rainfall: 1600, 1800 and 1200 mm, respectively) with explorations using the simple dynamic crop/soil model for dynamic simulation of nutrient balances, previously tested for the region. Field measurements indicated within-farm differences in average maize grain yields of 48% (2.7 vs. 1.4 t ha−1) in Vihiga and of 60% (1.5 vs. 0.6 t ha−1) in Teso, between fields that were close and far from the homestead, respectively. Extreme values ranged widely, e.g. between 4.9 and 0.3 t ha−1 for all the farms surveyed in Vihiga, where the average farm size was 0.6 ha. Maize grain yields tended to increase with increasing contents of soil C, total N, extractable P and exchangeable bases. However, the negative relationship between S factors and distance from the homestead was not as strong as expected, and yield variability was better explained by multiple regression models considering M factors such as planting date, plant density, resource use and weed infestation (40–60% across sites). Then, we analysed the variation in resource (cash, labour, N) use efficiency within farms of different resource endowments with the aid of the simulation model. N balances at plot scale varied from ca. +20 to −18 kg ha−1, from −9 to −20 kg ha−1 and from −16 to −18 kg ha−1 for the different fields of the high, medium and low resource endowment case-study farms, respectively. Labour productivities ranged between ca. 10 and 38 kg grain man-day−1 across field and farm types. The results indicate the need of considering within farm heterogeneity when designing soil fertility management interventions. Resource use efficiency was strongly affected by soil quality. As farmers invest more effort and resources in the more productive and less risky fields, the interaction between S and M factors leads to farmer-driven resource use efficiency gradients within smallholder farms.
Accelerator mass spectrometry age determinations of maize cobs (Zea mays L.) from Guilá Naquitz Cave in Oaxaca, Mexico, produced dates of 5,400 carbon-14 years before the present (about 6,250 calendar years ago), making those cobs the oldest in the Americas. Macrofossils and phytoliths characteristic of wild and domesticated Zea fruits are absent from older strata from the site, although Zea pollen has previously been identified from those levels. These results, together with the modern geographical distribution of wild Zea mays, suggest that the cultural practices that led to Zea domestication probably occurred elsewhere in Mexico. Guilá Naquitz Cave has now yielded the earliest macrofossil evidence for the domestication of two major American crop plants, squash (Cucurbita pepo) and maize.
