Seed yield and quality enhancement in off-season soybean (Glycine max L.) through plant growth regulators

A field and laboratory investigation entitled “Seed yield and quality enhancement in off-season soybean (Glycine max L.) through plant growth regulators" was carried out during the summer of 2024 at the Department of Seed Science and Technology, College of Agriculture, Junagadh Agricultural University, Junagadh. The field experiment was conducted using a Randomised Block Design (RBD) with a factorial concept at Sagdividi Farm; the laboratory study was carried out using a completely randomised design (CRD) at the Seed Testing Laboratory with seeds obtained from the corresponding field trial. The treatments consisted of two factors: stages of spraying [S1: 30 DAS, S2: 45 DAS and S3: 30 and 45 DAS] and plant growth regulators [P1: distilled water, P2: SA 400 ppm, P3: SA 800 ppm, P4: NAA 400 ppm, P5: NAA 800 ppm, P6: Thiourea 400 ppm and P7: Thiourea 800 ppm] along with an absolute control. Results of the field study revealed that spraying PGRs at both 30 and 45 DAS (S3), particularly NAA at 400 ppm, significantly enhanced highest plant height at maturity (cm), number of clusters per plant, number of pods per plant, number of pods per cluster, number of seeds per pod, number of seeds per plant, biological yield per plant (g), seed yield per plant (g) and test weight (g), with the lowest days to 50 % flowering and maturity. Correspondingly, the laboratory evaluation indicated that seeds derived from NAA 400 ppm treatments with dual sprays (30 and 45 DAS) recorded the highest germination (%), shoot length (cm), root length (cm), seedling length (cm), seedling dry weight (mg), seedling vigour index I and seedling vigour index II.