RESUMO
A cotonicultura da região Nordeste do Brasil enfrenta problemas de escassez hídrica ocasionada pela irregularidade do período chuvoso, proporcionando perdas no rendimento. Neste contexto, objetivou-se no presente estudo avaliar as trocas gasosas, o crescimento e a produção de genótipos de algodoeiro de fibra colorida sob déficit hídrico, variando as estratégias de manejo do déficit hídrico nas diferentes fases fenológicas das plantas. A pesquisa foi desenvolvida na área experimental da Universidade Federal de Campina Grande, localizado no município de Pombal, Paraíba. Foi utilizado o delineamento experimental em blocos ao acaso, em esquema fatorial 3 × 7, correspondendo a três genótipos de algodão colorido (‘BRS Rubi’, ‘BRS Jade’ e ‘BRS Safira’) e sete estratégias de manejo do déficit hídrico (40% da evapotranspiração real - ETr) em diferentes fases fenológicas. O genótipo ‘BRS Jade’ é o mais adequado para cultivo em condições de déficit hídrico com 40% da evapotranspiração real. O cultivo de algodoeiro de fibra colorida sob déficit hídrico na fase de floração ocasionou redução nas variáveis fisiológicas e no crescimento. O déficit hídrico durante a fase vegetativa e de formação da produção promoveu menores perdas na produção de algodão em caroço e massa de sementes totais dos genótipos ‘BRS Rubi’, ‘BRS Jade’ e ‘BRS Safira’ em relação às plantas cultivadas sem restrição hídrica.
Palavras-chave:
Gossypium hirsutum L.; Estratégia de irrigação; Fisiologia
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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).