Fertilizer dosage regimen and steckling transplanting for accelerated sugar beet seed production

Sugar beet seed production in India remains restricted due to its high-altitude vernalization requirement. To meet the growing need for high-quality seeds for bioethanol production, this study aimed to investigate how different fertilizers and planting methods affected the yield and quality of seeds in six ICAR–ISRI-developed genotypes over two years. Three planting methods: Steckling (E1), Direct Seeding (E2), and the Pit Method (E3), were tested along with two levels of fertilizer doses, viz., conventional (120:60:60 NPK, F1), and optimized (120:80:80 NPK, F2). Unlike previous international studies, this investigation represents the integrated planting methods and fertilizer regimes specifically optimized for Indian subtropical agro-climatic conditions, where vernalization is a major constraint. The optimized regime (F2) increased early bolting (> 90%) and flowering (60%–80%), harvest seed maturity by 1–5 d, and increased test weight by 8%–12% compared to F1. E1 led to the earliest seed harvest (184–200 d), E3 was in the middle (234–252 d), and E2 took longer to mature (> 400 d), but had higher percentages of bolting and flowering. F2 improved seed yield across genotypes by 15%–18% when compared to F1. The largest increase in seed yield was observed in the F2 regime by LKC 2006, with increases of 26.56%, 12.29%, and 19.77% in E1, E2, and E3, respectively. This study establishes a region-specific framework for sugar beet seed production under suboptimal vernalization conditions, demonstrating that combining the Steckling or Pit methods with the optimized 120:80:80 NPK regime can effectively enhance reproductive success and seed productivity in subtropical India. Overall, seed yield, test weight, and germination were significantly increased by combining the Steckling or Pit methods with the optimal fertilizer regime (120:80:80 NPK), offering a novel, climate-adapted strategy toward national seed self-sufficiency, and sustainable sugar beet-based bioethanol production.