GENETIC ANALYSIS OF SOME DROUGHT AND YIELD RELATED CHARACTERS IN SPRING WHEAT VARIETIES [Triticum aestivum L.]

Six genotypes of wheat [Triticum aestivum I.] representing different
agronomic characters crossed in all possible combination, excluding reciprocals, in
2000/2001 season. The six parents and their 15 F1 hybrids were evaluated during
2001/2002 growing season in the experimental from at Sakha Agric-Res. Stn, Kafer
EI-Sheikh Governorate. The studied traits were days to heading, days to maturity,
plant height, no. of spikes/plant, kernel weighVspike, no. of grains/spike, grain
yield/plant, leaf temperature, stomatal resistant and transpiration rate. The analysis of
variance revealed highly significant differences among genotypes for all studied traits
except no. of spikes/plant under stress environment. G.C.A and S.C.A mean squares
were highly significant for all studied traits and the magnitude of G.C .. A was greater
than S.C.A mean squares, suggesting that additive genetic effects were predominant
and played a major role in the inheritance of all traits. The genetic components Le.
additive and dominance were highly significant under stress environment for all traits.
• Significant dominance type of gene action was detected for all studied
characters, except for heading date and maturity date, the dominance component was
larger in magnitude than the additive one and the average degree of dominance in
these character revealed the existence of over dominance. The value (H2/4 H1) was
approximately equal to its maximum value for heading date, maturity date and number
of spikes/plant, whereas , it was deviated from 0.25 for other traits .Heritability
estimates in broad sense were high. however high to moderate heritability values (in
narrow sense) were detected for heading date, indicating that most of genetic
variance might be due to additive genetic effects ..
The genetic variance might be due to additive types of gene action, so
selection could be useful in this respect. Narrow sense heritability values were low for
all traits indicating that most of genetic variance might be due to non-additive genetic
effects.