Diallel Cross Analysis for Some Flax Genotypes Under Normal and Saline Environments

Abstract

The present investigation was conducted using six flax genotypes with their 15 crosses in F2 and F3 generations grown under normal salinity (Etay El-Baroud Exp. Station, El-Beheira Governorate) and stress salinity soil conditions (Tag El-Ezz Exp. Station, El Dakahlia Governorates) to determine salinity tolerance and combining ability in these entries (parents and their crosses). In two seasons, 2005/06 and 2006/07, the six parents (P1= S.413/3/3/1, P2= S.400/4/4/2, P3= S.402/1, P4 = S.421/6/4/5, P5 = Gentiana and P6= Daniela) and their 15 progenies were evaluated in a randomized complete block design with three replications at the two abovementioned locations.The collected data indicated that additive effects were more important than non-additive effects for straw weight and its two important components (plant height and technical stem length) as well as for seed weight and its all components under the two environments in both generations. While, both non-additive and additive genetic effects play an important role in the inheritance of No. of basal branches per plant. The interaction of general (GCA) and specific (SCA) combining ability with environments indicated that both additive and non-additive genetic effects are influenced by environments. However, additive genetic effects were more influenced by environmental fluctuation than non-additive effects for straw weight per plant and its two important components. P3 and P6 showed high GCA effects for straw weight and its two important components in most cases. However, P1 and P3 showed high GCA effects for seed weight and its two important components (No. of capsules and 1000-seed weight). While, P2 proved to be high general combiner for 1000-seed weight only. SCA effects indicated that the two crosses, P3P6 and P5P6 gave high SCA effects for straw weight, plant height and technical stem length, these crosses resulted from crossing between parents which one parent at least have high GCA effects for these traits. P1P2 for seed weight per plant and P1P6 for 1000-seed weight included high x low general combiner parents.Concerning salinity tolerance, P6 exhibited high yielding potential and low susceptibility to saline environments for straw weight and its two important components. Also, the cross P3xP6 showed high means for straw weight and its components, so it could be identified as low susceptible to salinity stress in both generations. The cross P5xP6 gave high yield potentiality and low susceptibility for straw weight and its two important components in F3 only. The results indicated that tolerant parents could produce tolerant hybrids. Hence the two crosses, P3xP6 and P5xP6 may be useful as potential breeding material for developing genotypes tolerant to soil salinity for straw weight and its components. P3 exhibited low or moderate susceptibility for seed weight and its two important components. However, P5 and P6 could be identified as high tolerant to salinity for No. of seeds per capsule. The two crosses P1xP2 and P2xP4 exhibited high or moderate tol...