Resource use efficiency of cotton in improved vs conventional planting geometry with exogenous application of bio-stimulant and synthetic growth retardant

Abstract Plant growth regulators and improved planting density are the innovative techniques in the establishment of more productive cotton crop. A field study was planned to assess the role of growth regulators in the resource utilization efficiency of cotton cultivars under different row spacing at Agronomic Research Area, Bahauddin Zakariya University Multan and Usmania Agricultural Farm, Shujaabad during Kharif 2012. The study was comprised of cotton cultivars viz. CIM-573 and CIM-598, cultivated under conventional (75 cm), medium (50 cm) and improved ultra-narrow row spacing (25 cm) and foliar spray of growth regulators viz. moringa leaf extract (MLE) and mepiquat chloride (MC), either alone or in combination, distilled water as a control. The application of MLE alone and in combination (MLE + MC) showed the promoting effect on crop growth rate, net assimilation rate, leaf area index, leaf area duration, sympodial branches and number of bolls leading to higher seed cotton yield of both cotton cultivars grown under conventional row spacing. While application of MC averts the plant growth without considerably improving the productivity. MLE being rich source of growth promoting hormone and nutrients showed its potential to a far greater extent under conventional row spacing in efficient utilization of available resources compared to MC and distilled water.