GENETICAL ANALYSIS OF YIELD AND ITS COMPONENTS FOR THREE FABA BEAN CROSSES USING SIX PARAMETER MODELS

Abstract

The objectives of this study were to estimates some genetic parameters of yield and its components as well as the extent of heterosis, inbreeding depression, heritability, genetic advance and behavior of gene action in three faba bean crosses. This investigation was carried out at Sakha Agricultural Research Station, ARC, Kafr El-Sheikh, Egypt during 2012 / 13, 2013 / 14 and 2014 / 15 seasons. Six populations; P1, P2, F1, F2 , BC1 and BC2 of the three crosses i., e, Giza 40 x D 2, Giza 40 x D5 and Giza 40 x D 8 were sown in randomized complete blocks design with three replications. The data were analyzed by generation mean analysis method proposed by Gamble (1962).Scaling test was significantly differed from zero for all traits in all crosses, indicating the presence of all types of non -allelic interactions. Positive and significant dominance gene effects was observed for most of the studied traits in the three crosses, whereas, the (additive x additive) gene effects were relatively more important than the additive (a) effects but less important than dominance effects. The dominance x dominance (dd) gene effects were more important and higher in magnitude than additive x additive (aa) epistatic effects in the inheritance of most studied traits in all crosses. Significant heterosis over mid-parent in desirable direction was found for yield and its components in the three crosses due to over-dominance in most cases. It could be concluded that selection for seed yield and its components should be delayed to later generations in breeding programs. Positive and highly significant heterosis over better - parent was obtained for number of pods and seeds / plant in the first and second crosses, seed yield / plant and 100-seed weight in the second and third crosses. Significant positive values of inbreeding depression were detected for number of branches / plant in the first and third crosses, number of seeds / plant in the first cross, number of pods / plant and seed yield / plant in the first and second crosses. Heritability estimates in broad-sense were higher than corresponding values of narrow-sense in all crosses. Heritability estimates in narrow-sense were low for plant height in the second cross (14.39 %) and seed yield / plant in the same cross (17.53 %), indicating that these traits were influenced by non-heritable effects. The high values of predicted genetic advance (Ga %) were associated with high values of narrow-sense heritability and vise-versa.