Genetic behavior and selection response of some bread wheat (Triticum aestivum L.)‎ genotypes under arid and semiarid environments

Abstract EN

Selection for newly promising bread wheat genotypes with high yield potential under arid and semi- arid conditions is the main objective of wheat breeding programs in ACSAD.

The present study was carried out to evaluate agronomic traits, genetic diversity and principle component analysis of 168 bread wheat genotypes selected in Fs generation.

The genotypes were evaluated for nine different yield contributing characters viz., days to heading, maturity date, plant height, number of spikes/plant, number of spikelets/spike, number of grains/spike, 1000-kernel weight, grain yield/plant and straw yield/plant and were grown in randomized complete block design with three replications under rainfed conditions at Izraa and kafrdan Agricultural Experiment Stations of ACSAD at Daraa governorate, Syria and Bekaa governorate, Lebanon, respectively for two growing seasons (2016/17 and 2017/18).

The most important results obtained can be summarized as follows : The combined analysis of variance indicated the homogeneous of significant differences between years for most studied traits.

The genotypes exhibited highly significant (P<0.01) for all traits studied in both and across seasons indicating considerable amount of variation among genotypes for each trait.

For days to heading (50%) and maturity dates the line 14 under Izraa as well as the three lines Line 52, Line 90 and Line 128 under kafrdan were the earliest across seasons.

While, for grain yield/plant the four new bred lines; 33, 71, 109 and 147 recorded the highest mean across seasons and under both sites which had values ranged from 27.14g for line 147 under Izraa and 29.40 g for line 33 under Kafrdan conditions.

Meanwhile, grain yield was positively correlated with each of no.

of spikes/plant (0894** and 0.901**), no.

of sikelets/spike (0.723** and 0.744**), no.

of grains/spike 0.696** and 0.744**) and 1000-kernel (0.681** and 0.556**) across seasons under the two sites, respectively.

Principle component analysis (PCA) showed existence of a high level of variability among the genotypes and allowed the division of the collection of genotypes into two groups (component 1 and 2) which gave an explanation of 84.74% and 84.59% of the total variance in the two sites.

The first component of PCA could justify most of the variance among genotypes (58.70% and 60.98% under Izraa and kafrdan conditions, respectively).

While, the second component could justify more than 25.04% and 23.61% under Izraa and kafrdan, respectively.

Cluster analysis of euclidean distances, classified the 168 genotypes into four main clusters divided into 15 and 10 intra cluster under Izraa and Kafrdan, respectively.

The first (I) and second (II) clusters was the largest and contained 24 and 20 genotypes (14.28% and 11.90% of total genotypes, respectively) under Izraa as well as the first (I), second (II), third (III) and fourth (IV) clusters recorded the highest number of sets; 19, 22, 33 and 25 genotypes (11.31, 13.09, 19.64% and 14.88% of total genotypes, respectively) under Kafrdan.

These results indicate that the high yielding genotypes 33, 71, 109 and 147 have more adaptability for under rainfed conditions in both sites and could be used in breeding programs to develop high yielding genotypes or distributed to the targeted farmers under arid and semi-arid environments.