Triple test cross analysis for seed yield and its components in sesame under water stress conditions

Abstract

Water deficit is a limiting factor in sesame cultivars yield, thus identification of genetic mechanisms of sesame traits under water stress conditions is essential to development of water stress tolerant genotypes. Hence, the triple test cross (TTC) analysis in F₂ population of the sesame cross (NA₇₆ ​× ​NA₅₄) was used. Since, 30 TTC families with their 13 respective parents were evaluated during the summer season 2020 under two irrigation treatments. i.e., normal irrigation with 5952.38 ​m³ ​hm⁻² of applied water, and water stress with 2976.19 ​m³ ​hm⁻² of applied water. This was implemented at the experimental field of Kafr El Hamam/Sharkia, Agricultural Research Station, Agricultural Research Center (ARC), Egypt. Additive (D) and dominance (H) gene actions as well as epistatic and its two components of additive ​× ​additive, additive ​× ​dominance plus dominance ​× ​dominance were involved in the inheritance of all studied traits under both irrigation treatments and their combined analysis. The degree of dominance (H/D)^0.5 verified the presence of partial dominance in most cases. The correlation coefficient between sums (additive) and differences (dominance) was non-significant, showing that dominant genes between lines were ambidirectional. The moderately water stress tolerant TTC families as the best selected families were found in families 22, 25, 10, 12, and 15. Therefore, postponing selection in these selected families to later segregating generations for all studied traits would be effective to exploit the positive effects of additive ​× ​additive epistasis.