Gibberellic acid and Boron application synergize enhanced seed production in a thermo-sensitive genetic male sterility (TGMS) based novel hybrid, Pusa Jawahar Rice Hybrid 56

The commercial adoption of hybrid rice is often constrained by low outcrossing rates in male sterile lines, necessitating agronomic interventions to improve pollination efficiency, outcrossing, and hybrid seed production. This study investigates the impact of gibberellic acid (GA₃) and boron on floral traits and yield-related parameters in the TGMS-based hybrid rice, Pusa PJRH 56. Multi-location trials were conducted across three agroclimatic zones represented by sites, Aduthurai, New Delhi, and Jabalpur, to evaluate the consistency of treatment effects under varying environmental conditions. Significant trait variations were observed across treatments and locations. Compared to the control, foliar application of GA₃ (200 ppm) and boron (1%) significantly enhanced key floral traits in both the parental lines. Stigma emergence was improved by 30.3%, glume opening angle by 51.2%, stigma receptivity by 21.3%in the female parent, and anther breadth by 13.1%and anther width by 21.3%in the male parent. These improvements facilitated increased pollen exposure and receptivity, which are critical for successful hybrid seed production. Additionally, agronomic traits such as plant height, panicle exertion, filled seeds per panicle, and seed yield per plot showed significant increases of 32.2, 87.4, 55.6, 152.6, and 103.0%, respectively. These findings demonstrate that GA₃ and boron work synergistically to improve floral development, seed formation, and overall seed yield. This study provides strong evidence for the exogenous application of GA3 and boron as an effective agronomic strategy to enhance hybrid seed production and overcome the limitations associated with TGMS-based hybrid rice cultivation.