Effect of deficit irrigation, phosphorous inoculation and cycocel spray on root growth, seed cotton yield and water productivity of drip irrigated cotton in arid environment

• Drip irrigation significantly increased seed cotton yield by 33.5% and saved 30% irrigation water in cotton.
• Significant water savings were obtained using deficit drip irrigation in cotton with modest yield loss.
• We evaluated the effect of PSB inoculation and cycocel spray on root growth, yield attributes and yield of cotton.
• Interaction effect of deficit irrigation and PSB inoculation and cycocel spray on seed cotton yield and WP of cotton was significant.

Irrigation water is scarce and expensive resource constraining crop production in arid and semi-arid region of India. Most producers’ aims to maximize yield per unit of water applied but it requires a better understanding of crop response to various levels of water stress. A field experiment was conducted during 2009–2011 to investigate the effect of deficit irrigation through drip irrigation; phosphorus solubilizing bacterial (PSB) inoculation and chloromequat chloride (cycocel) spray on seed cotton yield and water productivity (WP) of cotton. Experimental treatments comprised of three drip irrigation levels designated as 1.0 ETc (full irrigation as control), 0.8 ETc and 0.6 ETc (regular deficit irrigation) which receive 80% and 60% of the 1.0 ETc irrigation, were kept in main plots. The factorial combination of PSB inoculation and cycocel spray were included as good management practices (GMP) in sub-plots. A furrow irrigation treatment was also kept as absolute control. The result reveals that drip irrigation in cotton at 1.0 ETc significantly increased mean seed cotton yield by 33.5% and saved 30% irrigation water as compared to furrow irrigation which recorded 1859 kg ha−1 seed cotton yield with 582 mm irrigation water. Deficit irrigation at 0.8 ETc caused 17% water savings with only 6.4% reduction in yield as compared to 1.0 ETc. PSB inoculation and/or cycocel spray significantly increased number of bolls plant−1, boll weight and seed cotton weight plant−1 over control. The interaction effect of deficit irrigation and GMP was significant on seed cotton yield and water productivity. Therefore, deficit irrigation at 0.8Etc along with PSB inoculation and cycocel spray should be considered as useful tool for water saving and higher yield in arid and semi-arid regions where irrigation water supplies are limited.