| چکیده انگلیسی مقاله |
Introduction and Objective: Wheat, as one of the most important crops, occupies about 20% of the world's cultivated area. In the FAO report, more than 90% of Iran is classified as arid and semi-arid. The impact of drought stress on crops is devastating every year, resulting in yield losses of 17%. It is therefore of high importance to research to improve crop resilience to drought stress and minimize water losses in agriculture. This study aimed to answer two issues: i) to investigate the relationships between yield and yield components with physiological traits and use these relationships in selecting high-yielding cultivars under normal irrigation and water moisture conditions at flowering stage; ii) to evaluate the relative importance of traits affecting the performance of the studied genotypes to determine criteria for selecting high-yielding genotypes for breeding programs. Material and methods: To explore the effect of moisture stress at flowering stage, four genotypes were investigated as the main factor (A) by factorial experiment based on the randomized complete block design (RCBD) with three replications under the normal and moisture stress conditions at flowering stage as the sub-factor (B) in the research field. We conducted an analysis of variance, mean comparison, and canonical correlation analysis after measuring the morphological, phenological, and physiological traits of the genotypes studied to investigate the relationship between yield and yield components, physiological traits, and the relative importance of traits affecting yield. Results: Analysis of variance results revealed significant differences between genotypes for most traits studied. Under normal irrigation conditions and moisture stress, Arum genotype was recognized as the best one in terms of biological yield, spike length, grain number per spike, flag leaf length and grain number in spikelet traits. Whereas, Mihan genotype outperformed than others in terms of plant dry weight, plant grain yield, number of grains per spike, days to spike formation, flag leaf length, root dry weight, root volume and number of grains per spikelettraits. Based on the results of this canonical correlation analysis, there was a significant correlation between yield and yield components under both normal and stress conditions between the two canonical variables. To increase grain yield and 1000-grain weight under normal field irrigation conditions, increased malondialdehyde concentrations, leaf hydrogen peroxide content, proline content, peroxide, and catalase content, and decreased chlorophyll a and total chlorophyll concentrations may be considered appropriate selection criteria. The results of canonical correlation analysis under field stress conditions revealed that to increase 1000-grain weight, number of grains per spike and grain yield, traits such as increased malondialdehyde, chlorophyll b concentration, protein content and peroxidase and decreased proline content, chlorophyll a concentration, and catalase are important and influential factors. Conclusion: Analysis of variance and mean comparison results exhibited that high yield of Arum genotype is related to biological yield, spike length, grain number per spike, flag leaf length and grain number per spikelet.While the high yield of the Mihan genotype is associated with traits such as plant dry weight, grain yield, grain number per spike, days to spike formation, flag leaf length, root dry weight, root volume, and grain number per spikelet. Furthermore, according to canonical correlation analysis it can be argued that under normal irrigation and moisture stress conditions in the greenhouse, higher concentration of malondialdehyde and peroxidase and lower concentration of chlorophyll a are appropriate selection criteria to increase 1000-grain weight and grain yield. |