Study of Relationships between Root Traits and Yield and Yield Components of Bread Wheat under Rainfed Conditions

Breeding new crop cultivars with efficient root systems carries great potential to enhance resource use efficiency, plant adaptation to unstable climates and improve yields. Current study was conducted to investigate the relationship between root characteristics with yield and yield components in 24 lines and cultivar of bread wheat using complete randomized block design with three replications in rainfed conditions of research farm of the University of Zanjan in 2017-18 and 2018-19 growing seasons. The results of combined analysis of variance showed the difference between year and high diversity between genotypes measured for most traits. According to the results of the study of genetic parameters, the highest heritability was related to the number of grains per spike (70.328%) and the heritability of the most root traits was low. There was a negative correlation between yields with the most root traits but root diameter. The results of sequential path analysis showed that in the first stage of chain 1000-grain weight, number of spikes per square meter and number of seeds per spike affected grain yield, and in the second stage, root dry weight and diameter greater than 25cm deep and root volume to a depth of 25cm with effects on 1000-grain weight, root volume greater than 25cm deep and root dry weight to a depth of 25cm with effects on spike number per square meter and root volume to a depth of 25cm with effects on seed number per spike, they Indirectly affected grain yield. The results of factor analysis led to the identification of four factors that explained 82.45% of the differences between the data. Based on the results of cluster analysis, the studied genotypes were divided into three groups. The cultivars and lines in the second group had the highest yield with the highest root volume, diameter, dry weight, surface and length to a depth of 25cm.