GENETIC ANALYSIS OF SESAME YIELD VIA QUADRALLEL MATING SYSTEM (Sesamum indicum L.)

Abstract

Sesame (Sesamum indicum L.) is recognized as one of the oldest crop in the world. Sesame has the highest oil content (50 - 60%) among oil crops. The sesame oil is very stable due to the presence of a number of antioxidant such as sesamin, sesamolin and sesamol. Therefore, the production of this important oil seed crop has to be stepped up by evolving high yielding cultivars. Additive gene action plays a major role in selecting superior segregates from crosses. However, Allared proved that favorable epistatic combination have a great role in yield superiority in self- as well as in cross-pollinated crops. He reported that the results of marker- assisted dissections of quantitative traits have clearly established that epistasis played a major role in the inheritance of quantitative traits and in the genetic basis of heterosis. In the context, Rawlings and Cockerham (1962) stated that quadrallel mating design provides additional information about the components of epistatic variances, besides additive and dominance genetic variance. Besides, it provides information about the order in which parents should be crossed to obtain superior segregates. It should be taken into consideration, however that this mating system requires one additional crop season for generating of experimen- tal material as compared to diallel and partial diallel designs, which adds to the experimental cost. Quadrallel model has eight covariance of relatives and seven orthogonal partitions of double crosses sums of squares. Many researchers inves- tigated genetic components of variance using different mating designs. Kamala (1999) indicated that non-additive affects in the from of dominance was more important than additive in plant height, number of branches/pl., number of capsules/pl., number of seeds/capsules, seed index and seed yield/pl. Sumathi and Kalaimani (2000), Manivannan and Ganesan (2001) and Arulmozhi et al. (2001) studied gene action using line x tester method. They found that non- additive gene actions including additive x additive interaction control days to 50% flowering, days to maturity, plant height, length of fruiting zone, number of capsules/pl. and seed yield/pl. Bakheit et al. (2001) estimated the additive, domi- nance and epistatic components of genetic variation for yield and yield components by triple test cross. They reported that mean squares from the genetic analysis of variance and the over all epistatic gene effects were highly significant difference for all studied characters. El-Shakhess (2003) studied gene action for yield and yield components by using fifteen half diallel crosses in F1 and F2 generations. She reported that the dominance genetic variance was more important than additive genetic variance for plant height, height of first capsules, length of fruiting zone, number of capsules/pl. and seed yield/pl. in both F1 and F2 generations. Attia et al. (2004) investigated nature and magnitude of different gene effects of yield and yield components via parents (P1, P2), hybrids (F1, F2) and backcrosses (Bc1 and Bc2). Their results revealed the importance of dominance gene action for plant height, length of fruiting zone, number of branches/pl., number of capsules/pl. and seed yield/pl. Also, they indicated that all combinations of epistatic gene effects were of significant magni- tude reflecting their importance in the inheritance of studied traits. In India, Kumar et al. (2006) revealed that seed yield determined by dominance x domi- nance type of genetic system and over dominance was associated with duplicate dominant epistasis of yield and its components. Kim et al. (2007) reported that overdominance was exhibited by number of capsules/pl. While, partial dominance by plant height, capsule setting stem length and seed yield/pl.
The present study was undertaken to study epistasis beside additive and dominance effects and genetic compo- nents of variance for yield and its compo- nents using quadrallel analysis. The ultimate goal of these crosses is to be utilized in enhancing favorable combina-The present study was undertaken to study epistasis beside additive and dominance effects and genetic compo- nents of variance for yield and its compo- nents using quadrallel analysis. The ultimate goal of these crosses is to be utilized in enhancing favorable combinationsof the weblike type in order to improve sesame characters.