ABSTRACT
Cotton cultivation in the Brazilian Northeast region faces water scarcity problems caused by the irregularity of the rainy season, leading to losses in yield. In this context, the objective of the present study was to evaluate the gas exchange, growth, and production of colored-fiber cotton genotypes under water stress, varying the water deficit management strategies in the different phenological stages of the plant. The study was carried out in the experimental area of the Federal University of Campina Grande, located in the municipality of Pombal, Paraíba, Brazil. A randomized block design was used, in a 3 × 7 factorial scheme, corresponding to three colored cotton genotypes (‘BRS Rubi’, ‘BRS Jade’, and ‘BRS Safira’) and application of water deficit (40% of actual evapotranspiration - ETr) management strategies in seven phenological stages of the crop. The ‘BRS Jade’ genotype is the most suitable for cultivation under water deficit conditions with 40% of the actual evapotranspiration. Colored-fiber cotton cultivation under water deficit in the flowering stage caused a reduction in physiological variables and growth. Water deficit during the vegetative and yield formation stages promoted lower losses in the production of seed cotton and total seed weight of the genotypes ‘BRS Rubi’, ‘BRS Jade’, and ‘BRS Safira’.
Keywords:
Gossypium hirsutum L.; Irrigation strategy; Physiology
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Means followed by the same lowercase letter indicate there is no significant difference between water deficit strategies (Scott-Knott, p > 0.05) for the same genotype, and means followed by the same uppercase letter for the same strategy indicate that the genotypes do not differ by Tukey test, p > 0.05. Vertical bars represent the standard error of the mean (n = 3). Water deficit management strategies 1 - plants under full irrigation throughout the cycle (1-120 days after sowing - DAS); 2 - water stress in the vegetative stage (20 - 60 DAS); 3 - water stress in the flowering stage (61 - 75 DAS); 4 - water stress in the vegetative and flowering stages (20 - 60 and 61 - 75 DAS).
Means followed by the same lowercase letter indicate there is no significant difference between water deficit strategies (Scott-Knott, p > 0.015 ) for the same genotype, and means followed by the same uppercase letter for the same strategy indicate that the genotypes do not differ by Tukey test, p > 0.05. Bars represent the standard error of the mean (n = 3). Water deficit management strategies 1- plants under full irrigation throughout the cycle (1-120 days after sowing - DAS); 2- water stress in the vegetative stage (20 - 60 DAS); 3- water stress in the flowering stage (61 - 75 DAS); 4- water stress in the vegetative and flowering stages (20 - 60/ 61 - 75 DAS).
Means followed by the same lowercase letter indicate there is no significant difference between water deficit strategies (Scott-Knott, p > 0.05) for the same genotype, and means followed by the same uppercase letter for the same strategy indicate that the genotypes do not differ by Tukey test, p > 0.05. Bars represent the standard error of the mean (n = 3). Water deficit management strategies 1- plants under full irrigation throughout the cycle (1-120 days after sowing - DAS); 2- water stress in the vegetative stage (20 - 60 DAS); 3- water stress in the flowering stage (61 - 75 DAS); 4- water stress in the vegetative and flowering stages (20 – 60/ 61 - 75 DAS).
Means followed by the same lowercase letter indicate there is no significant difference between water deficit strategies (Scott-Knott, p > 0.05), and means followed by the same uppercase letter indicate that the genotypes do not differ from each other by Tukey test, p > 0.05. Bars represent the standard error of the mean (n = 3 for strategies and n = 3 for genotypes). Water deficit management strategies 1- plants under full irrigation throughout the cycle (1-120 days after sowing - DAS); 2- water stress in the vegetative stage (20 - 60 DAS); 3- water stress in the flowering stage (61 - 75 DAS); 4- water stress in the vegetative and flowering stages (20 – 60/ 61 - 75 DAS).
Means followed by the same lowercase letter indicate there is no significant difference between water deficit strategies (Scott-Knott, p > 0.05) for the same genotype, and means followed by the same uppercase letter for the same strategy indicate that the genotypes do not differ by Tukey test, p > 0.05. Bars represent the standard error of the mean (n = 3). Water deficit management strategies 1- plants under full irrigation throughout the cycle (1-120 days after sowing - DAS); 2- water stress in the vegetative stage (20 - 60 DAS); 3- water stress in the flowering stage (61 - 75 DAS); 4- water stress in the vegetative and flowering stages (20 – 60/ 61 - 75 DAS).
Means followed by the same lowercase letter indicate there is no significant difference between water deficit strategies (Scott-Knott, p > 0.05), and means followed by the same uppercase letter indicate that the genotypes do not differ from each other by Tukey test, p > 0.05. Bars represent the standard error of the mean (n = 3 for strategies and n = 3 for genotypes). Water deficit management strategies 1- plants under full irrigation throughout the cycle (1-120 days after sowing - DAS); 2- water stress in the vegetative stage (20 - 60 DAS); 3- water stress in the flowering stage (61 - 75 DAS); 4- water stress in the vegetative and flowering stages (20 - 60/ 61 - 75 DAS); 5 - water stress in the yield formation stage (76 - 120 DAS); 6- water stress in the vegetative and yield formation stages (20 - 60/76 - 120 DAS); 7- water stress in the flowering and yield formation stages (61 – 75/76 - 120 DAS).
Means followed by the same lowercase letter indicate there is no significant difference between water deficit strategies (Scott-Knott, p > 0.05), and means followed by the same uppercase letter indicate that the genotypes do not differ from each other by Tukey test, p > 0.05. Bars represent the standard error of the mean (n = 3 for strategies and n = 3 for genotypes). Water deficit management strategies 1- plants under full irrigation throughout the cycle (1-120 days after sowing - DAS); 2- water stress in the vegetative stage (20 - 60 DAS); 3- water stress in the flowering stage (61 - 75 DAS); 4- water stress in the vegetative and flowering stages (20 - 60/ 61 - 75 DAS); 5 - water stress in the yield formation stage (76 - 120 DAS); 6- water stress in the vegetative and yield formation stages (20 - 60/76 - 120 DAS); 7- water stress in the flowering and yield formation stages (61 – 75/76 - 120 DAS).