Assessing the Impact of Deficit Irrigation on Yield and Phenology of Bt Cotton (Gossypium hirsutum L.)

Aims: To Evaluate the Impact of Different Irrigation Levels on Cotton Yield and Phenological Traits and To Determine the Optimal Fertigation Level for Cotton Cultivation. Study Design:  Factorial Randomized Block Design. Place and Duration of Study: Department of Agronomy, CCSHAU, Hisar, Haryana, India between June 2019 and July 2020. Methodology: The experiment was set up in open fields with replicated plots to ensure the reliability of the results. The study included three irrigation levels: I1 (1.0 Etc), I2 (0.8 Etc), and I3 (0.6 Etc). Additionally, four fertigation levels were also tested: F1 (control), F2 (50% Recommended Dose of Fertilisers, RDF), F3 (75% RDF), and F4 (100% RDF). The factorial randomized block design with three replications was used to manage the plots. Key phenological traits, such as days to squaring, 50% flowering, 50% boll development, and maturity, were recorded. Yield components including seed cotton yield, number of bolls per plant, and individual boll weight were also measured. Bt cotton genotype RCH 776 was used for the study. All the agronomic practices were done as per the recommendations of CCSHAU. Statistical analysis was performed to determine the significance of differences between treatments. Results: The results indicated that the highest irrigation level, I1 (1.0 Etc), led to prolonged phenological stages but achieved the highest seed cotton yield of 3854 kg/ha. In contrast, the lowest irrigation level, I3 (0.6 Etc), resulted in the lowest yield at 3327 kg/ha. Additionally, I1 outperformed I3 in terms of boll number and individual boll weight. Regarding fertigation treatments, F4 (100% RDF) produced the highest seed cotton yield (4404 kg/ha), boll weight (4.09 g), and number of bolls per plant (53/Plant). These findings suggest that both irrigation and fertigation significantly influence cotton yield and its components. Conclusion: This study concluded that deficit irrigation, particularly at the I2 level (0.8 Etc), can optimize water use efficiency without significantly compromising yield. The highest fertigation level (F4) was found to produce the best yield outcomes. These optimized irrigation and fertigation practices are recommended for enhancing cotton production in arid regions like Haryana, with further validation needed to ensure their reliability and effectiveness in different environmental conditions.