Combining ability and heterosis for flax straw and seed yield components

Fifteen crosses generated from six diverse parents in half diallel mating design were evaluated in 2020/2021 season to estimate combining ability and heterosis in flax for improving yield and its various components. The analysis of data showed that variance due to genotypes, parents and crosses were highly significant, indicating sufficient variability existed in populations. Variance of parents vs. crosses as an indication to average heterosis was significant for all the studied traits except technical length and fibre percentage traits. The analysis for combining ability illustrated significant variance due to both general combining ability (GCA) and specific combining ability (SCA) for all the studied traits, indicating presence of both additive and non-additive gene actions in the expression for these traits. GCA/SCA ratio was more than unity for all studied traits except number of basal branches and number of capsules/plant traits, indicating that additive gene effects were more important than non-additive gene effects for control the inheritance of these traits. S.620/1/3 (P1) was good combiner for all studied traits and Sakha 3 (P2) and Belinka (P3) were good combiners for most of the studied traits. Six crosses were the good combination for the most of the studied traits and particularly three crosses (S. 620/1/3 x Sakha 3, S. 620/1/3 x Belinka and S. 620/1/3 x Sozana) exhibited positive significant heterosis for most of the studied traits. Therefore, good combiners and best crosses combinations can be used for improvement of yield and their components in the programs of flax breeding.