Multivariate analysis of interactive effects of sowing dates and sesame genotypes

Six divergent genotypes of sesame (Sesamum indicum L.) were crossed using a half diallel mating design according to Griffing (1956) excluding reciprocal crosses, to estimate stability for studied traits under three sowing dates in the experimental farm at Agricultural Research Station in Ismailia Governorate during summer season 2018. The 15 hybrids and their 6 parents were grown in field experiments in two geographical locations (Ismailia and El-Sharkia Governorates) and two seasons (2019 and 2020) under three sowing dates (April 1st and 2nd (SD1), May 1st and 2nd (SD2) and June 1st and 2nd (SD3) in Ismailia and Sharkia, respectively. A split plot design was used in randomized complete blocks with four replications, the main plots included planting dates while the 21 genotypes were in sub-plots. Combined analysis of variance over locations and seasons gave highly significant differences. Most of the interactions between the studied factors showed high significance for most of the traits under study. Additive Main effects and Multiplicative Interaction (AMMI) analysis for seed yield for 12 environments (two locations, two seasons and three sowing dates) showed significant effect of environments, genotypes and their interactions. The E2, E3, E8 and E9 had high mean seed yield above the grand mean environments values and are considered suitable and favorable for sesame seed production due to its low interactive effects. Sesame genotypes 7, 18, 10, 19, 12, 13, 15 were nearly close to the origin and thus the most stable and less responsive to the GEI (Genotype-by-Environment Interaction). In contrast, genotypes 1, 20, 8, 11 and 2 were far from the origin, sensitive to environmental changes and their yields are unstable. Keywords: Sesame, half diallel, sowing dates, AMMI, biplo