| چکیده انگلیسی مقاله |
Extended Abstract
Introduction and Objective: One of the main elements of sustainable development of any country is providing enough food at a suitable price for the people of that society. Cereals and its 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 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 changes poses a significant threat to most agricultural products in tropical and subtropical regions in worldwide. Drought stress is one of the consequences of climate changes that negatively effects on growth and yield of wheat. The predictions of climate changes models show that the average global temperature will increase between 0.5 and 3.7 degrees Centigrade by the end of 2100. Due to the simultaneous effects of increasing temperature and decreasing rainfall, it is expected that the intensity and frequency of drought increased. It is also expected that the effects of climate changes on the agricultural products will be more severe in arid and semi-arid regions such as Iran, hence the creation of new cultivars with high yield in regions that involved drought is necessary, so in order to determine effective agro-morphological traits on grain yield under dry conditions were evaluated winter wheat cultivars of 24 lines and cultivars of bread wheat.
Materials and 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. After the traits were measured, the data were analyzed and the averages were compared using Duncan's method. In order to investigate the relationships between traits, multivariate statistical analyzes including correlation analysis, regression analysis and principal components analysis were performed.
Results: The results of analysis of variance and mean comparison showed that high variability among genotypes for most of the measured traits. There was a significant difference between the genotypes in terms of all traits except relative leaf water content, 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 was related to Hashtrood variety. Cross Sablan variety was identified as the latest tern variety and line number 8 as the earliest genotype in this study. Among the investigated genotypes, line number 2 was the highest genotype. The results of correlation analysis showed that there was 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. Also, 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. Relative leaf water content showed a positive and significant correlation with peduncle length. The results of stepwise regression analysis, considering grain yield trait as dependent variable and other traits as independent variables, showed that four variables, number of seeds per spike, number of spikes per square meter, thousand kernel weight, and spike length accounted for 93.8% of grain yield changes. They justified the seed. The results of analysis into principal components 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 results of analysis into main components, 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 and the yield is severely reduced. On the other hand, genotypes with short spike length but the number of spikes per square meter is more with the number of seeds per square meter, have a higher grain yield, and these genotypes can be used for crossing in future breeding programs.
|