Effect of plant growth regulators on biophysical, biochemical traits and productivity in Bt cotton

Abstract

A field experiment was conducted during kharif 2019-20 to study the “Effect of plant growth regulators onbiophysical, biochemical traits and productivity in Bt cotton at the Agricultural Research Station (ARS), University ofAgricultural Sciences, Dharwad. The experiment was laid out in Randomized Block Design (RBD) with nine treatmentsconsisting of four growth regulators (NAA, GA3, ethylene and mepiquat chloride) at different concentration with threereplications. Biophysical traits like photosynthetic rate, transpiration rate and stomatal conductance and biochemical traitslike total chlorophyll content and NR activity was improved significantly due to the foliar spray of growth regulators(GA3 @ 50 ppm at 50 and 75 DAS) as compared to control. Foliar sprays GA3 @ 50 ppm at 50 and 75 DAS recordedsignificantly higher seed cotton yield and number of bolls per plant and higher net returns followed by foliar sprays of NAA@ 20 ppm and GA3 @ 40 ppm at 50 and 75 DAS as compared to control. Lowest seed cotton yield, boll number, bollweight and net returns were recorded in control. The higher seed cotton yield with foliar sprays of PGRs was mainlyattributed to its close association with yield components like number of bolls/plant, boll weight and harvest index