Genetic diversity of some bread wheat genotypes based on cluster and principal component analyses under rainfed conditions

الملخص EN

Breed wheat considered to be one of the most important export and strategic cereal crop in the world and Arab region in terms of production and utilization.

ACSAD cereal breeding program improved a number bread wheat (Triticum aestivum L.) genotypes under rainfed conditions.

In the present investigation, 120 promising lines and 2 cultivars were evaluated to estimate the extent of genetic diversity.

Field experiments was conducted in 2018/19 and 2019/20 cropping seasons by utilizing 122 wheat genotypes using Randomized Complete Block Design where genotypes were replicated three times under rainfed conditions at Izraa Agricultural Experiment Stations of ACSAD at Daraa governorate, Syria and 14 characters were recorded; heading date (days), maturity date (days), flag leaf area (cm2), basal angle of flag leaf ("), plant height (cm.), number of spikes/plant, Spike Length (cm.).

number of spikelets/spike, number of grains/spike, 1000-kernel weight (g), main spike grain yield(g.), grain yield (t./ha), straw yield (t./ha) and biological yield (t./ha.).

- Analysis of variance revealed highly significant differences (P<0.05 or 0.01) among genotypes for all traits in both and across seasons indicating considerable amount of variation among genotypes for each trait.

For days to heading (50%) and maturity date the six newly genotypes ACSAD 1286, ACSAD 1288, ACSAD 1226, ACSAD 1234, ACSAD 1240 and ACSAD 1282 were the earliest.

While, the thirteen genotypes; ACSAD 1196, ACSAD 1258, ACSAD 1300, ACSAD 1302, ACSAD 1306, ACSAD 1332, ACSAD 1334, ACSAD 1364, ACSAD 1372, ACSAD 1373, ACSAD 1388, ACSAD 1414 and ACSAD 1416 showed best performance by producing highest one or more of yield attributes.

-A significant positive correlation was observed among grain yield with most of studied characters.

The computed coefficient for yield showed that the four traits; flag leaf area, no.

of grains/spike, no, of spikelets/spike and 1000-kernel weight proved to be the major grain contributors under rainfed conditions.

-The first three principal components based on the Euclidean similarity matrix explained (58.61%, 13% and 7.23%, respectively) of the total variation, Cluster analysis revealed that the 122 genotypes were grouped into three main clusters and 11 intra cluster, the first (I) and second (II) clusters was the largest and contained 27 and 23 genotypes (22.13% and 18.85% of total genotypes, respectively) which exhibited high degree of genetic diversity.

-Generally, it has been observed the presence of variability among the genotypes and the high yielding genotypes ACSAD 1196, ACSAD 1258, ACSAD 1300, ACSAD 1302, ACSAD 1306, ACSAD 1332, ACSAD 1334, ACSAD 1364, ACSAD 1372, ACSAD 1373, ACSAD 1388, ACSAD 1414 and ACSAD 1416 have more adaptability and could be distributed with the Arab production efficiency trials on the Arab countries for possible selection, registration and release as new commercial cultivars for similar environments under rained conditions.