Enhancement of physiological efficiency of boro rice using exogenous gibberellic acid

An experiment was conducted to study the effect of plant growth regulators using gibberellic acid (GA₃) on the physiological efficiency of Boro rice. The physiological parameters and their relation with growth and yield attributes were analysed in the experiment. The experiment consisted of four treatments viz., T1: application of 10 ppm GA₃ at early tillering stage, T2: application of 10 ppm GA₃ at panicle initiation, T3: application 10 ppm GA₃ at early tillering + at panicle initiation and T4: control. It was revealed that GA₃ applied on boro rice at different stages of growth had improved significantly the physiological traits namely biomass allocation, chlorophyll contents, reducing, non reducing and total sugars, stomatal characters with significant effect on growth parameters leading to enhancement in grain yield. GA₃ applied at early tillering + panicle initiation stage was found to be superior over other treatments. Gibberellic acid treatment significantly increased the NR activity and made 17.68% higher photosynthetic contribution after flowering thereby enhanced 12.5% higher grain yield over control.