Gene effects for different metric traits under normal and high temperature stress environments in wheat (T. aestivum L. Em Thell)

The present investigation was conducted to analyze gene effects for grain yield and its components under two different environments. Nine wheat genotypes were selected to generate the experimental material comprised six parental and segregating generations (P1, P2, F1, F2, BC1 and BS1 of BC1 of each of the following six crosses – PBW 343 x WH 283, PBW 343 x WH 542, PBW 343 x PBW 435, UP 2565 x UP 2425, EIGN 1 x Raj 3765 and EIGN 8 x UP 2425. Joint scaling tests revealed the presence of epitasis. Six parameter model revealed the significance of additive gene effects (d) for biological and grain yield and their components in most of the crosses. The relative magnitude of (h) was higher than (d) in all the crosses for most of the characters while additive x additive (i) effects appeared to be significant for grain yield per plant (E1) and number of grain per spike (E2) in PBW 343 x WH 283. Significant (i) type of interaction was recorded in PBW 343 x WH 542 for number of grain per spike (E1), number of tillers per plant (E2) in PBW 343 x PBW 435 and for 1000-grain weight in UP 2565 x UP 2425. Pedigree method and simple selection in crosses like PBW 343 x PBW 435, UP 2565 x UP 2425, PBW 343 x WH 283 and PBW 343 x WH 542 should be used for improvement of traits governed by additive and additive x additive gene effect.