Hybrid rice offers a substantial yield advantage over conventional varieties, yet seed production in thermo-sensitive genic male sterility based hybrids is often limited by low seed set, poor grain filling, and suboptimal seed physiological quality. Improving the reproductive efficiency and metabolic performance of thermo-sensitive genic male sterility hybrids is therefore essential for reliable hybrid seed production. This study investigated the individual and combined effects of foliar-applied gibberellic acid (GA3; 100 and 200 ppm) and boron (0.5 and 1%) at the early heading stage (5–10%) on seed yield, metabolic activity, and seed quality traits in the TGMS hybrid PJRH56 (Pusa 1S × PRR158). Field experiments were conducted using a randomized block design with three replications. The combined treatment GA3 (200 ppm) + B (1%) (T8) produced the most significant improvements across reproductive and seed quality parameters. T8 enhanced spikelet fertility (59.80%; a 119% increase over control), seed yield per plot (479.93 g; 73% increase), and 1000-seed weight (22.42 g). Key seed quality indicators, including seedling vigor indices (SVI-I: 3538.53; SVI-II: 10.58), α-amylase activity (5.48 µmol maltose/min), and seed boron content (12.29 µg/g), were also significantly elevated. These improvements reflect the synergistic role of GA3 and boron in enhancing pollination efficiency, boron translocation, grain filling, and metabolic up-regulation during seed development. Enhanced α-amylase activity and reserve utilization further strengthened seedling establishment. Overall, foliar application of GA3 (200 ppm) with boron (1%) at early heading offers a practical and effective strategy to enhance seed physiological efficiency, quality, and vigor in TGMS hybrid rice, supporting more reliable hybrid seed production under changing climatic conditions.
Pashwan et al. (Mon,) studied this question.