Study of genetic diversity and cluster analysis for morphological traits of bread wheat under drought stress conditions

Bread wheat is one of the grains in the world that provides 20% of the plant-derived protein to the people of the world (Acevedo et al., 2002; Godfray et al., 2010). Drought is an important environmental factor limiting the production of wheat and other crops in the world. Water scarcity has made the production of higher drought-tolerant cultivars an important goal in many breeding programs. One of the goals of wheat cultivation in arid and semi-arid regions is to achieve cultivars that are more tolerant of drought stress at the end of the season in conditions of water restriction and lack of irrigation and have less yield reduction. By achieving such figures, it is possible to increase the efficiency of operations in those conditions and to a large extent prevent the waste of water resources. The aim of this study was to identify agricultural traits associated with changes in wheat grain yield under drought stress and drought-tolerant lines.

In this study, 111 lines along with 3 cultivars of Shahid Narin, Barzegar, and Sistan in the form of repeated experiments (Agent) in 1396 in the research farm of the Research Center located in Yazd city (at 15 degrees and 53 minutes to 40 degrees And 54 minutes east longitude and 46 degrees and 31 minutes to 15 degrees and 32 minutes north latitude and altitude 1200 meters). In order to check the production capacity of the lines, the control was repeated at intervals of every 20 lines. Each line was planted in 2 lines of 2.5 m with a planting distance of 20 cm. In order to investigate the effect of drought stress at the end of the season on the relevant traits in the post-flowering stage, irrigation was stopped. During the growing season, grain yield, yield, and morphological components were evaluated and compared with control cultivars. A simple correlation was used to obtain the relationship between the traits. To identify the main variables that affect grain yield, multi-variable analysis was used by stepwise regression analysis.

The experimental results showed that there is a great variety among the studied lines. Regression tests showed that traits such as 1000-grain weight, number of days to ripening, spike length, plant height, and spike weight had a positive and significant effect on grain yield and explained a significant share of yield changes. The classification of lines is based on cluster analysis by the UPGMA method in 9 groups. Based on the obtained results, 15 genotypes were selected that had more grain yield and some more suitable agricultural characteristics than other genotypes and cultivars.

Although drought stress affects most plant growth traits, this effect depends on the time the plant is exposed to water stress and the lines being tested. The results of this study show that water stress has a different effect on the growth of wheat lines and shows that the ability of bread wheat lines to tolerate drought stress is different. Also, the genetic material in this experiment could be a valuable resource that, in addition to removing new traits, provides a great variety for breeders to improve and produce drought-tolerant wheat cultivars.