(. Breeding For Drought Tolerance In Maize (Zea mays, L

Abstract

The mam objectives of the present investigation are to study the effect of drought on yield, yield components and other• morpho­ physiological traits,••genotypic and phenotypic coefficient of variability, broad sense heritability, compare the expected and actual gain fi"om selection, combining ability and type of gene action under favourable and water stress environments in two maize populations; Giza-2 (Ev-9) and Pop.45 (Ev-3). In 1997 late swnmer season, the two populations were grown and I 000 plants were self pollinated from each population. Three hundred selfed ears from each population were selected and evaluated in separate trails in incomplete block design in 1998 season according to Hallauer and Miranda (1981). In 1999 early season, the 40 white S 1 lines were top crosses to the three testers; Giza-2, SC-10 and SC-129, while the 35 yellow S 1 lines were top crosses to pop.45; SC-156 and SC-I 59 testers. Two white and two yellow populations were fanned each fi•om I 0

S I lines selected on the basis of relative yield and drought susceptibility index (DSI). ln 2000 summer season, 120 white and I 05 yellow top crosses and the new four populations were evaluated under favourble imd water stress environment using RCBD with four replications for each group. Data were analyzed for combining ability according to Kemphorne (1957) and for evaluation trial according to Steel and Torrie (1980).