The Study of different irrigation regimes influences on heritability and some physiological characteristics in wheat genotypes (Triticum aestivum L.).

Wheat (Triticum aestivum) is the most important crop in terms of area under cultivation and plays an important role in meeting human nutritional needs. In Iran, wheat is grown in different climatic conditions and is exposed to stress at different stages of growth. Water stress is the most important cause of reduced wheat yield. Improvement of drought tolerant cultivars is one of the most important strategies to deal with water shortage and has faced many problems in arid areas. Physiological traits are vital in the survival and adaptation of plants to environmental stresses and therefore attention to physiological indicators in order to study the rate of drought resistance is one of the important aspects of drought resistance in plants and is one of the objectives of this study. In order to analyze the effects of three different humidity regimes on physiological characteristics and yield, of wheat, 3 different experiments were carried out in completey randomized block designs with 3 replicates. The 3 different humidity regimes . Ten different wheat genotypes were evaluated in this experiment. After analyzing the results of the first experiment, genetic materials were selected for the second year experiment and cultured in conditions similar to the planting conditions of the first experiment, and stomatal characteristics were measured as another group of physiological characteristics on these cultivars. The results showed that there was a significant difference between genotypes in terms of most traits. The reaction of wheat cultivars was different in three experiments, but drought stress in all types of stresses reduced the evaluated traits. Oxley with high WUE in different irrigation conditions compared to other genotypes had the highest and Ehdaei 82 had the lowest WUE. In normal conditions, the highest biological yield was seen in Ehdaei 81 and Ehdaei 79. It seems that this cultivar has the highest yield by increasing the weight of biomass and green tissue. Oxley showed the highest RWC in normal irrigation conditions. In such water conditions, the highest RWL was also seen in Oxley. Therefore, it can be concluded that Oxley, although it had a high RWC, was not able to maintain the relative water content. The results of the variance components of the evaluated traits show that for most of the traits, the genotypic and phenotypic variance was higher than the stress under normal conditions. According to the results, it is clear that all traits except RWL had high heritability, which shows that these traits are less affected by the environment. Due to the existence of genetic diversity and high heritability for traits, it is possible to produce desirable cultivars through selection and hybridization. Results for stomatal characteristics showed that in drought stress, Stomatal Frequency increases and Stomatal Length and Stomatal Width Decreases. There is a negative relationship between the Stomatal Frequency and drought tolerance in wheat, but it is a more tolerant that had more stomatal with smaller size. The results showed that drought stress in all types of stress reduced the physiological traits evaluated. Low RWL and high RWC were recognized as a mechanism of survival and high WUE was introduced as an indicator of stress tolerance. The results showed that the RWC of flag leaf was controlled by the additive effects of the gene and had a high heritability; Therefore, high genetic efficiency can be expected from selection for this trait. Results for stomatal characteristics showed that in drought stress, Stomatal Frequency increases and Stomatal Length and Stomatal Width Decreases. There is a negative relationship between the Stomatal Frequency and drought tolerance in wheat, but it is a more tolerant that had more stomatal with smaller size.