Plant Growth and Flowering Behaviour of Sesame Genotypes as Influenced by Growth Regulators

A two-year, field experiment was conducted to assess the plant growth and flowering behaviour of sesame genotypes as influenced by growth promoters and growth retardants. The experiment was carried out with the objective to study the effect of growth regulators on pollen sterility with minimum effect on plant growth parameters. Experiment was conducted in split plot design with six main plots and eight sub plots replicated thrice with the plot size of 4 m x 1.5 m each. The main plot comprised six genotypes viz. V1: Rama, V2: Savitri, V3: Suprava, V4: Tilottama, V5: Shubhra, V6: Smarak. Sub plot comprised of eight plant growth regulators treatments viz., T1: GA3 @ 100ppm, T2: GA3 @ 200ppm, T3: GA3 @ 300ppm, T4: 2,4-D @ 10ppm, T5: 2,4-D @ 25ppm, T6: 2,4-D @ 50ppm, T7: 2,4-D @ 100ppm, T8: Control (water spray). The results of the experiment indicated that, Savitri followed by Tilottama recorded the highest plant height at 60 days after sowing with GA3 @ 300 ppm, while at maturity, variety Shubhra under GA3 @ 100ppm and Rama under GA3 @ 300 ppm had the maximum height with non-significant variation. Tilottama, with the application of GA3 @ 300ppm, produced maximum number of primary branches at 60 days after sowing and Suprava followed by Tilottama produced maximum number of primary branches maturity. Shubhra under GA3 @ 100ppm application produced maximum number of secondary branches at 60 days after sowing and maturity. GA3 produced first flowering and 50% flowering earlier than all other treatments. Whereas, 2,4-D delayed flowering for all the six genotypes. Higher concentrations of 2,4-D negatively impacted plant growth and pollen fertility with maximum pollen sterility at 2,4-D @ 100ppm, for all the genotypes. The study highlights the significant influence of GA₃ and 2,4-D on plant growth and flowering across different varieties of sesame. Overall, GA₃ @ 300 ppm improved plant growth parameters. Hence, GA₃ @300ppm can be adopted for effective growth enhancement strategies of sesame varieties. With the deleterious effects of 2,4-D, maximum pollen sterility was observed in Rama with application of 100 ppm and minimum pollen sterility was noted for Rama with GA3 @ 200 ppm. For induction of pollen sterility of female line with minimum effect on plant growth parameters, these findings may be utilized for production of hybrid seed of sesame.