Volume 17, Issue 2 (5-2025)
J Crop Breed 2025, 17(2): 140-151 |
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Sadegh Ghol Moghadam R, Saba J, Shekari F, Roustaii M. (2025). Determining the Traits Affecting Grain Yield in Bread Wheat under Rainfed Conditions. J Crop Breed. 17(2), 140-151. doi:10.61882/jcb.2024.1538
URL: http://jcb.sanru.ac.ir/article-1-1538-en.html
URL: http://jcb.sanru.ac.ir/article-1-1538-en.html
1- Department of Plant Genetics and Production Engineering, Faculty of Agriculture, University of Zanjan, Zanjan, Iran
2- Dryland Agricultural Research Institute (DARI), Agricultural Research Education and Extension Organization (AREEO), Maragheh, Iran
2- Dryland Agricultural Research Institute (DARI), Agricultural Research Education and Extension Organization (AREEO), Maragheh, Iran
Abstract: (737 Views)
Extended Abstract
Background: One of the main elements of sustainable development of any country is to provide enough food at a suitable price for the people of that society. Cereals and their products are the main part of most human diets in developed and developing countries, which constitute a major part of dietary energy and nutrients. Wheat (Triticum aestivum L.) is one of the most widely used crops in the world and has the second highest production in grains following corn. Wheat provides approximately 20% of calories and protein to 4.5 billion people in various forms. Climate change poses a significant threat to most agricultural products in tropical and subtropical regions worldwide. Drought stress is one of the consequences of climate change that negatively affects the growth and yield of wheat. The predictions of climate change models show that the average global temperature will increase between 0.5 and 3.7 °C by the end of 2100. The simultaneous effects of increasing temperature and decreasing rainfall are expected to increase the intensity and frequency of drought. It is also expected that the effects of climate change on agricultural products will be more severe in arid and semi-arid regions, such as Iran. Hence, it is necessary to create new cultivars with high yield in regions exposed to drought. Thus, agro-morphological traits affecting grain yield under dry conditions were evaluated in winter wheat cultivars of 24 lines and cultivars of bread wheat.
Methods: The experiment was conducted in a complete randomized block design with three replications under rainfed conditions. In this study, 12 advanced lines along with the WAZ line and 11 autumn wheat cultivars, named Sardari, Homa, Azar2, Takab, Ouhadi, Rasad, Hashtrood, Baran, Sain, Sadra, and Cross Sabalan, were evaluated in the Research Field of the Faculty of Agriculture, Zanjan University, during the agricultural year 2017-2018. For this purpose, traits such as days to booting, days to heading, days to anthesis, days to physiological maturity, relative leaf water content (RWC), canopy temperature difference, plant height, spike length, peduncle length, peduncle extrusion, number of spike per m2, spikelets per spike, number of grain per spike, thousand kernel weight, grain yield, biomass, and harvest index were measured in this study. Data were analyzed after measuring the traits, and the averages were compared using Duncan's method. The relationships between traits were investigated using multivariate statistical analyses, including correlation analysis, regression analysis, and principal component analysis (PCA).
Results: The results of the analysis of variance and mean comparisons revealed high variability among genotypes for most of the measured traits. There was a significant difference between the genotypes in terms of all traits, except for RWC, canopy temperature difference, number of spikes per square meter, and thousand-kernel weight. The results of Duncan's mean comparison showed that the highest grain yield belonged to the Hashtrood variety. The Cross Sablan variety was identified as the latest tern variety, and line 8 as the earliest genotype in this study. Among the investigated genotypes, line 2 was the highest genotype. The results of correlation analysis showed a high and significant positive correlation between grain yield and the number of seeds per spike and a negative and significant correlation between yield and spike length. The number of seeds per spike had a positive and significant correlation with the harvest index. Moreover, the number of seeds per spike had a negative and significant correlation with the thousand kernel weight and the number of spikes per square meter. RWC showed a positive and significant correlation with peduncle length. The results of stepwise regression analysis, considering grain yield trait as a dependent variable and other traits as independent variables, showed that four variables (the number of seeds per spike, the number of spikes per square meter, thousand kernel
Methods: The experiment was conducted in a complete randomized block design with three replications under rainfed conditions. In this study, 12 advanced lines along with the WAZ line and 11 autumn wheat cultivars, named Sardari, Homa, Azar2, Takab, Ouhadi, Rasad, Hashtrood, Baran, Sain, Sadra, and Cross Sabalan, were evaluated in the Research Field of the Faculty of Agriculture, Zanjan University, during the agricultural year 2017-2018. For this purpose, traits such as days to booting, days to heading, days to anthesis, days to physiological maturity, relative leaf water content (RWC), canopy temperature difference, plant height, spike length, peduncle length, peduncle extrusion, number of spike per m2, spikelets per spike, number of grain per spike, thousand kernel weight, grain yield, biomass, and harvest index were measured in this study. Data were analyzed after measuring the traits, and the averages were compared using Duncan's method. The relationships between traits were investigated using multivariate statistical analyses, including correlation analysis, regression analysis, and principal component analysis (PCA).
Results: The results of the analysis of variance and mean comparisons revealed high variability among genotypes for most of the measured traits. There was a significant difference between the genotypes in terms of all traits, except for RWC, canopy temperature difference, number of spikes per square meter, and thousand-kernel weight. The results of Duncan's mean comparison showed that the highest grain yield belonged to the Hashtrood variety. The Cross Sablan variety was identified as the latest tern variety, and line 8 as the earliest genotype in this study. Among the investigated genotypes, line 2 was the highest genotype. The results of correlation analysis showed a high and significant positive correlation between grain yield and the number of seeds per spike and a negative and significant correlation between yield and spike length. The number of seeds per spike had a positive and significant correlation with the harvest index. Moreover, the number of seeds per spike had a negative and significant correlation with the thousand kernel weight and the number of spikes per square meter. RWC showed a positive and significant correlation with peduncle length. The results of stepwise regression analysis, considering grain yield trait as a dependent variable and other traits as independent variables, showed that four variables (the number of seeds per spike, the number of spikes per square meter, thousand kernel
weight, and spike length) accounted for 93.8% of grain yield changes. The results of PCA showed that the first five components had an eigenvalue higher than one and accounted for the largest amount of variance, so that the first five components had 80.21% of the total variance. In addition, the first, second, third, fourth, and fifth components accounted for 22.03, 19.12, 17.46, 13.05, and 8.55% of the total variance, respectively. Based on the PCA results, the number of seeds per spike, grain yield, and harvest index were positively related to the second component.
Conclusion: In rainfed conditions, high vegetative growth and high biomass production cause the complete drainage of moisture in the early growing season, and the plant faces severe stress after the pollination stage, severely reducing the yield. On the other hand, genotypes with a short spike length but with a more number of spikes per square meter and a more number of seeds per square meter showed a higher grain yield, and these genotypes can be used for crossing in future breeding programs.
Conclusion: In rainfed conditions, high vegetative growth and high biomass production cause the complete drainage of moisture in the early growing season, and the plant faces severe stress after the pollination stage, severely reducing the yield. On the other hand, genotypes with a short spike length but with a more number of spikes per square meter and a more number of seeds per square meter showed a higher grain yield, and these genotypes can be used for crossing in future breeding programs.
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