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Initial fluorescence -Fo of the mini watermelon cv. Sugar Baby as a function of nitrogen doses, at 65 days after sowing. Vertical bars represent the standard error of the mean (n=5). Means with different letters represent that the treatments differ from each other by Tukey's test (p<0.05).
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Salt stress is highlighted as one of the limiting factors for the establishment of agriculture in the semiarid region of Northeastern Brazil. In this context, it is essential to look for new strategies aiming at minimizing the effects of salt stress on the crops. The present work aimed to evaluate the photochemical efficiency, photosynthetic pigmen...
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This study aimed to evaluate the photosynthetic pigments and growth of the West Indian cherry cv. BRS 366 Jaburu in the post-grafting phase as a function of the salinity levels of the irrigation water and nitrogen fertilization under greenhouse conditions, in the municipality of Campina Grande-PB. The study was performed in randomized blocks, consi...
Citations
... Several studies have shown that watermelon is sensitive to salinity (COSTA et al., 2013;SOUSA et al., 2016;SILVA et al., 2020;LIMA et al., 2020a). According to Ayers and Westcot (1999), the threshold level of salinity in irrigation water for watermelon is 3.0 dS m -1 . ...
... Sugar Baby, 55 days after sowing. Unlike this study, Silva et al. (2020) evaluated the photochemical efficiency of mini watermelon cv. Sugar Baby under different strategies of use with saline water and nitrogen fertilization and verified that only the initial fluorescence was significantly affected by nitrogen doses. ...
... Sugar Baby, at 55 days after sowing. When analyzing the photosynthetic pigments of mini watermelon, Silva et al. (2020) observed significant differences caused by irrigation management strategies only for chlorophyll b and total chlorophyll, at 65 days after sowing. Table 4. Summary of the analysis of variance for the contents of chlorophyll a (Chl a -mg g -1 FM), chlorophyll b (Chl b -mg g -1 FM), total chlorophyll (Chl T -mg g -1 FM) and total carotenoids (Car -mg g -1 FM) of mini watermelon cv. ...
This study was conducted with the objective of evaluating the quantum yield, photosynthetic pigments and biomass accumulation of mini watermelon cv. Sugar Baby, under strategies of irrigation with saline water and potassium fertilization. The experiment was conducted in a randomized block design, in a 8 × 3 factorial scheme, with three replicates, corresponding to eight strategies of irrigation with saline water applied at different phenological stages of the crop (control - irrigation with low-salinity water throughout the crop cycle, and salt stress in the vegetative, vegetative/flowering, flowering, flowering/fruiting, fruiting, fruiting/ fruit maturation and fruit maturation stage) and three potassium doses (50, 100 and 150% of the recommendation). The dose of 100% corresponded to 150 mg of K2O kg⁻¹ of soil. Two levels of electrical conductivity of water were used: 0.8 and 4.0 dS m⁻¹. Irrigation with water of 4.0 dS m⁻¹ continuously in the vegetative and flowering stages increased the initial fluorescence and decreased the quantum efficiency of photosystem II of mini watermelon fertilized with 100 and 150% of K recommendation. Fertilization with 50% recommendation did not interfere in the fluorescence parameters of the mini watermelon, regardless of the irrigation management strategy. Chlorophyll a synthesis is inhibited by salt stress in the vegetative/flowering, flowering, flowering/fruiting, fruiting/maturation stages, as well as for total chlorophyll, except for the flowering stage. Application of 4.0 dS m⁻¹ water in the flowering, fruiting/maturation and maturation stages promoted greater biomass accumulation in mini watermelon.
Keywords:
Citrullus lanatus ; Salt stress; Potassium
The objective of this study was to evaluate the water status, photosynthetic pigments, and photochemical efficiency of mini watermelon plants under salt stress and phosphate fertilization. The experiment was conducted in pots under greenhouse conditions in Pombal, PB, Brazil. The experimental design used was randomized blocks in a 5 × 4 factorial scheme, with five levels of electrical conductivity of irrigation water - ECw (0.3, 1.3, 2.3, 3.3, and 4.3 dS m-1) and four doses of phosphorus (60, 80, 100, and 120% of the recommendation), with three replicates. The relative water content in the tissues decreased with the increase in ECw levels in all phosphorus doses, with decreases of 7.05, 7.81 and 8.83% per unit increase in ECw, in plants fertilized with 80, 100 and 120% P2O5. On the other hand, ECw levels increased electrolyte leakage, regardless of phosphorus doses of the recommendation. The synthesis of photosynthetic pigments and the quantum efficiency of photosystem II were inhibited by increasing water salinity from 0.3 dS m-1 in plants grown under phosphorus doses above 60% of the recommendation. Water salinity from 0.3 dS m-1 reduced chlorophyll b contents, initial, maximum, and variable fluorescence of mini watermelon plants, with a decrease of 11.86, 4.51, 4.53, and 4.54% per unit increment of ECw, respectively.
O uso de tecnologias influencia diretamente a produtividade no agronegócio, sendo elas determinantes para uma produção economicamente viável em ambientes com condições climáticas adversas, como o semiárido brasileiro. Assim, este artigo faz a análise, por meio de uma revisão sistemática, das tecnologias usadas no meio agrícola na região de clima semiárido brasileira, o bioma Caatinga. Os resultados apresentam inicialmente as tecnologias de convivência com o semiárido ou técnicas sociais, com destaque para os métodos de manejo do solo, aproveitamento da água da chuva e preparo de ração animal. Já em relação às tecnologias propriamente ditas, as evidências convergem para a utilização tecnológica direcionada à viabilidade da produção, diversificação e ao tempo de colheita, principalmente de culturas irrigadas. Outrossim, o melhoramento genético contribuiu para a propagação de culturas resistentes e para o aumento da população de animais. Ao mesmo tempo que foi possível identificar o nível tecnológico da atividade agrícola na Caatinga, a qual, na maior parte do bioma, apresenta baixo uso de tecnologias, caracterizado por atividades de subsistência, mão de obra familiar e monocultura, por outro lado, em polos locais agrícolas, ocorre a utilização de sistemas integrados e agropecuária de base biológica.
The occurrence of water sources with a high concentration of salts stands out as a limiting factor for production in Northeast Brazil. Thus, the search for strategies that minimize the effect of salt stress on crops is of fundamental importance. In this context, this study was conducted with the objective of evaluating the production and post-harvest quality of Sugar Baby mini-watermelon fruits under different irrigation management strategies with saline water and potassium fertilization. The experiment was conducted in a greenhouse, using a randomized block design, in an 8 × 3 factorial scheme, with three replicates, corresponding to eight saline water irrigation management strategies (No stress throughout the crop cycle; irrigation with saline water in the vegetative, vegetative/flowering, flowering, flowering/fruiting, fruiting, fruiting/maturation and fruit maturation stages) and three doses of potassium (50, 100 and 150% of the recommended dose). The dose of 100% corresponded to 150 mg K2O kg⁻¹ of soil. Water with low and with high electrical conductivity (0.8 and 4.0 dS m⁻¹, respectively) was used. Irrigation with water of 4.0 dS m⁻¹ in the flowering and fruit maturation stages is a promising strategy for the cultivation of mini-watermelon, as it does not compromise production. Fertilization with 50% of K2O recommendation can be used in the cultivation of mini-watermelon without losses in yield. Mini-watermelon plants fertilized with 150% of K2O recommendation and irrigated with water of high salt concentration continuously in the vegetative/flowering and fruiting stages reduced the contents of soluble solids and ascorbic acid in the fruits.
Key words:
Citrullus lanatus L.; salt stress; osmoregulator
Irregularity or shortage of rainfall in semi-arid regions forces farmers to use low-quality water to irrigate crops. The present study aimed to assess the water-use efficiency and post-harvest quality of ‘Sugar Baby’ mini watermelon in response to different electrical conductivities of the nutrient solution [2.5 (control), 3.5, 4.5, 5.5 and 6.5 dS m⁻¹], in a floating hydroponic system. The experimental design was completely randomized, with four replicates. The water consumption, production and water-use efficiency were evaluated, as well as qualitative and physico-chemical variables of the fruits. The total water consumption of the plants during the crop cycle varied between 43 (6.5 dS m⁻¹) and 54 (2.5 dS m⁻¹) L plant⁻¹ among the treatments, with water-use efficiency of 0.031 kg L⁻¹. The greatest reductions due to the nutrient solution salinity were observed for the rind thickness and fruit mass (8.80 and 5.69 %, respectively, per unit increase in dS m⁻¹). The salinity of the nutrient solution did not influence the soluble solids content and fruit maturity index, but it had a negative effect on the pH and titratable acidity.
KEYWORDS:
Citrullus lanatus L.; soilless cultivation; brackish water
