STUDIES OF CORRELATION AND PATH COEFFICIENT ANALYSIS FOR SOME YIELD ATTRIBUTES IN SOME BREAD WHEAT GENOTYPES UNDER TWO ENVIRONMENTS.

This study was conducted at Res. farm of Shandaweel Agric. Res. station,
Agric. Res. Cen. (ARC) Egypt. during the period of 2001/2002 —2003/2004 seasons,
to estimates of phenotypic, genotypic correlations and path coefficient analysis in live
bread wheat genotypes, F1 hybrids and three F2 populations under two treatments of
irrigation (normal and drought stress).
The results showed that grain yield/plant had positive and significant
correlations with each of number of spikes / plant, 100 kernel weight, plant height and
days to maturity under the two treatments of irrigation ¡n the parents and F, hybrids for
both magnitudes of correlations. Meanwhile, in the F2 populations grain yield / plant
showed varied values of corr&ations from positive and significant to insignificant in
both phenotypic and genotypic correlations according to cross with previous traits.
Similarly, phenotypic and genotypic corre’ations between grain yield f plant and each
of number of kernels / spike and days to heading were negative in the parents only
under normal irrigation, while the relationships of these traits was positive in the F1
hybrids under the two treatments of irrigation.
Also, the resulls revealed that number of spikes / plant had positive and
significant correlation with each of 100 kernel weight and days to maturity in the
parents under the two irrigation treatments and positive insignificant correlations with
each of plant height and days to heading in all studied genotypes under the wrigation
treatments, while it showed negative and significant correlations with number of
kernels f spike ¡n the parents and ¡n the F2 popu’ations of crosses No 2 (p x p) and
No 3 (p x p5) .
The phenotypic and genotypic correlations were positive and significant
between number of kernels / spike and each cf kernel weight and number of days to
heading in the parents under normal irrigation and ¡n the F1 hybrids with kernel weight
and plant height. Meanwhile, in the F2 generations the relationships differed from
positive to negative correlations according to population.
Also, the relationships between 100 kernel weight and each of plant height,
days to heading and days to maturity varied from positive to negative significant or
insignificant according to genotypes and irrigation treatments. Plant height revealed
positive correlations with days to heading in the parents and Fi hybrids under the two
irrigation treatments and cross No 1 (P1 x P2) in the F2 generation under drought
stress only.
b Days to heading showed negative correlations with days to maturity in the
parents and in the F1 hybrids under normal irrigation, while had positive and significant
correlations under drought stress with all studied generations.
Path coefficient analysis under normal irrigation showed that grain yield was
directly affected by number of kernels I spike in all studied generations and number of
spikes f plant in the (Fihybrids and cross No3 ¡n F2 population). Meanwhile, under
drought stress , grain yield was affected directly by number of spikes I plant ¡n the
parents and in the F2 population of cross No3, number of kernels / spike