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Germination percentage of maize varieties
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Maize (Zea mays L.) is a widely grown crop with a high rate of photosynthetic activity due to its C4 pathway leading to higher yields of grain and a potential for biomass. It is predominantly cross-pollinated crop, a feature that has contributed to its wide morphological variability and geographical adaptability. Abiotic stress such as drought stre...
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Globally, water stress is the major abiotic stress, which contributes huge in yield losses of major crops including maize. To breed for drought tolerance, the first and foremost step is to search resistance at genotypic level among genetically diverse maize germplasm on the basis of most reliable traits. To find out the best responsible and reliabl...
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... In response to water-deficit conditions, some plants adjust their leaves structure to decrease transpiration (Hameed et al., 2012). Egyptian cotton cultivars are differentiated in drought stress responses (Yehia & El-Menshawie, 2008;Dahad et al., 2012;Gamez et al., 2019;Pawar et al., 2020;Yehia, 2020;Ibrahim et al., 2021;Zaki & Radwan, 2022). ...
... These accumulated compounds acted as cellular osmoregulators agents, protected enzymes and proteins against damage, supported energy supply, and improved the antioxidant activity of plants under stress conditions. A similar trend was obtained by Yehia & El-Menshawie (2008), Yehia (2020), Pawar et al. (2020), and Ibrahim et al. (2021), who stated that Egyptian cotton cultivars differed in drought stress tolerance via the cotton leaves content of proline and their ability for accumulating it in leaves. ...
... Water-deficit conditions adversely affected all cotton cultivar pigment content (Table 8), which might be related to the increased ROS production and oxidative stress, in parallel with water-deficit, close stomatal conductance, and chloroplast damage (Ali & Ullah, 2020;Pawar et al., 2020). The accumulation of osmoprotectant compounds (soluble sugars, phenol, amino acids, proline, and antioxidants) might be attributed to their serving as ROS scavengers, maintaining turgor, and stabilizing cellular membranes under water stress conditions to improve cotton plant tolerance. ...
WATER deficiency is the most common abiotic stress in cotton production in Egypt. Although, cotton plants react strongly to soil moisture, water-deficit conditions during squaring and flowering stages diminish plant growth and productivity. The experiment was conducted to evaluate the physiological response of three Egyptian cotton cultivars (Giza 94, 96 and 97), under irrigation intervals (normal and severe water-deficit conditions) and with spraying with growth inducers [calcium(Ca)-boron(B) and mixed amino acids] and their interactions on the leaves chemical constituents and yield components during the 2020 and 2021 seasons. The experiment design was a split-split plot with three replicates. The main plots included three cotton cultivars, the subplots included two irrigation intervals and the sub-subplots included spraying with growth inducers at squaring and flowering stages (400ppm). The results revealed that the performance of the three cotton cultivars was significantly different in chemical constituents and yield components via their different genetic potentials, with the best results registered by Giza 97 compared to Giza 94 and 96. Water-deficit conditions significantly reduced leaves pigment content and all yield components, but significantly improved all osmolyte compounds (total soluble sugars, total phenol, total free amino acids, free proline and total antioxidant capacity) compared to normal conditions. Spraying with growth inducers significantly enhanced the chemical constituents and yield components compared to untreated plants in relation to their positive effects in improving photosynthesis, sugar biosynthesis and all cotton cultivar yields. Giza 97 sprayed with CaB under normal conditions recorded the best results compared to other treatments.
... Throughout its entire growth cycle, maize crop requires adequate moisture (Min et al. 2016;Masereka et al. 2019;Yin et al. 2016). Moisture inadequacy during the germination period reduces the germination rate, whilst moisture inadequacy at the seedling stage affects seedling survival rate, vigour and growth, which compromise plant growth and development of the subsequent stages, ultimately leading to a decrease in yield (Pawar et al. 2020;Adewale et al. 2018). Drought stress during the anthesis period often increases the anthesis and silking interval (ASI) and causes kernel abortion (Kahiu et al. 2013). ...
Drought tolerance is a very complex trait, controlled by multiple genes, difficult to identify and evaluate in maize. Here, we employed RNA-seq transcriptome analysis to identify key differentially expressed genes (DEGs) responding to drought stress in maize at different crop growth stages. Resultantly, 666, 2417, and 7375 drought-responsive DEGS were detected at the flare, tasseling, and grain-filling stages, respectively. Among these, two candidate genes, DnaJ and a putative WAK family receptor-like protein kinase, involved in molecular chaperon activities and cell signal transduction, respectively, were found to be co-expressed across all three crop growth stages, and were suggested as the main contenders underpinning drought tolerance in maize. Further, by way of qRT-PCR analysis, other drought resistance indices, 5-level-classification criterion and two sets of maize verification materials, we tested the utility of using DnaJ gene expression as a potential index for drought resistance evaluation in maize. We observed that DnaJ successfully classified the different materials into their expected drought resistance categories. Moreover, RNA-seq analysis and qRT-PCR analysis results were consistent to each other. These observations showed that DnaJ gene expression can accurately, consistently and conveniently be employed as a potential index for drought resistance evaluation of maize cultivars. Besides augmenting the commonly used indices for drought resistance evaluation, DnaJ gene expression method takes into account the crop developmental stages, physiological processes and the yield change dynamics, and therefore, is suggested as a much more simple, accurate, flexible, reliable and convenient alternative. This method can play a huge role in drought resistance screening of maize materials for breeding.
... MMRI. Water stress-induced reductions in biomass production and final seed yield are common phenomena in crop plants [97][98][99]. However, the extent of reductions in yield and biomass are crop species-and cultivar specific [100]. ...
Different strategies including the exogenous use of micronutrient-chelated amino acids are being employed for better crop yield with limited fresh water for irrigation. The present study was conducted to assess the effects of foliar-applied Zn-lysine (Zn-Lys) on maize growth and yield under limited irrigation, in relation to physio-biochemical mechanisms such as the plant–water relations, photosynthetic efficiency, antioxidant defense mechanism, amino acid accumulation and nutrient acquisition. The experiment comprised two maize cultivars (MMRI and Pearl), two irrigation levels and three levels of Zn-Lys (0.25, 0.5 and 0.75%). Zn-Lys fertigation was found to be effective in reducing the negative impacts of limited water supply on grain yield, associated with improved photosynthetic efficiency, water relations, antioxidative defense mechanism and reduced lipid peroxidation in both maize cultivars. Zn-Lys-induced improvement in antioxidative mechanisms was associated with improved content of non-enzymatic antioxidants and activities of antioxidant enzymes. Foliar-fertigation with Zn-Lys also significantly improved the contents of various amino acids including Lys, as well as uptake of nutrients in both maize cultivars. In conclusion, the 0.5% level of Zn-Lys was found to be effective in ameliorating the negative impacts of water stress for better grain yield in both maize cultivars that can also be used as an important environment-friendly source of Zn to fulfill maize Zn deficiency.
... For example, for maize seedlings it has been reported that water deficit produces reductions in cell turgor, cell division and cell enlargement (Anjorin et al., 2017); consequently, drought may modify the root/shoot biomass ratio, and decrease gas exchange and assimilated storage capacity (Chen et al., 2016;Akinwale et al., 2017). The genetic diversity available within the maize genotypes has allowed to find genotypes having the ability to prevent growth losses induced by drought at the seedling stage (Mabhaudhi and Modi, 2010;Bashir et al., 2016;Anjorin et al., 2017;Badr et al., 2020;Pawar et al., 2020), while other researchers have reported tolerant species populations (including maize) having the ability to compensate the growth losses induced by drought (Xu et al., 2010;Chen et al., 2016). Therefore, it is postulated here that it should be possible to find maize genotypes adapted to dry environments having both drought tolerance during the stress and an adequate post-stress recovery at the seedling stage. ...
Drought is the main limiting factor for maize production, and climate change can aggravate this water scarcity. One way to mitigate this problem is to plant drought tolerance maize genotypes. In landrace maize grown under rainfed conditions there are drought-adapted genotypes, which can be used in breeding programs for drought tolerance. The objective of this study was to evaluate the effect of an early water deficit on the seedling growth of 41 maize landraces from Nuevo León, Mexico, plus seven varieties, by means of drought tolerance indices based on biomass accumulation during both stress and post-stress recovery period, for identifying tolerant and susceptible genotypes. This study was performed at 2016 in Texcoco, Mexico (19°27’N, 98°54’W, 2241 masl). In the greenhouse, 96 treatments were compared (48 genotypes × two soil water regimes: without and with drought) under randomized complete blocks experimental design. After the drought stress period, normal irrigation was resumed for 15 days for recovery. In maize landraces there is genetic diversity in drought tolerance. Landraces GalTrini and SITexas outstanded as the most water deficit tolerant, whereas landraces Berrones, Rodeo, Sabanilla, Carmen, AraTrini and the inbred line L65 were the most drought susceptible. The total biomass measured before water stress was not related to drought adaptability. This study demonstrates that the post stress recovery is more important in drought stress adaptability than the drought resistance, regarding root biomass, shoot biomass and total biomass. Thus, to include the post stress recovery in drought tolerance studies can produce a more precise genotypic classification for drought stress resistance and adaptability.
The present study was conducted to evaluate eight white inbred lines of maize and their F1 crosses under normal and drought stress conditions to estimate combining ability and heterosis for grain yield and associated traits. The evaluation was extended to include two transcription factor genes known to be associated with abiotic stresses in plants, namely are DREB2 and CBF4. The results showed significant mean squares (MS) of irrigation treatment were showed for the studied traits. The MS of parents, crosses, and genotypes were determined to be highly significant under both and across irrigation levels, with the exception of the anthesis-silking interval and stay green under normal irrigation, number of ears plant-1 and ear diameter under both irrigation levels for parents and genotypes, and anthesis-silking interval, number of ears plant-1 and ear diameter under both irrigation regimes for crosses. Grain yield and most other traits showed significant differences (MS) associated with both General combining ability (GCA) and specific combining ability (SCA) under both irrigation regimes, demonstrating the importance of both additive and non-additive genetic effects in the expression of performance traits. The drought sensitivity index indicated that the best parents were (P-53), (P-137) and (P-86), and the best crosses were (P-86×P-96), (P-53×P-96), (P-96×P-137) and (P-53×P-137) which gave the highest yield under both environments. The parental line (P-86) had positive and highly significant GCA effects. The crosses (P-17×P-96), (P-8×P-96), (P-8×P-171), (P-24×P-86), (P-86×P-96), (P-86×P-171), and (P-96×P-171), gave the highest specific combinations under both irrigation regimes for grain yield and some of the associated traits. The highest level of heterosis (heterobeltiosis) for grain yield was obtained in the crosses (P-8×P-96), (P-8×P-137), (P-8×P-171), (P-96×P-137), and (P-96×P-171) under both irrigation regimes. The quantitative gene expression analysis of two transcription factors (DREB2 and CBF4) was successful for triplicates of four genotypes P1, P5, P5×P6, and P1×P8. Based on the obtained CT values, in contrast to CBF4, the foldchange of the DREB2 showed a significantly higher change in gene expression in the drought-tolerant genotypes versus the drought-sensitive ones. The detected change confirmed the importance of the DREB2 transcription factor in the drought tolerance mechanism, and its usefulness as a molecular marker for the detection and selection of drought-tolerant genotypes.
