Genetic Dissection Of Stem Water-Soluble Carbohydrates And Agronomic Traits In Wheat Under Different Water Regimes

Wheat(Triticum aestivum L.) is an important crop contributing to the global food supply as well as providing economic security. However, drought is a major abiotic stress that affects wheat production. In this research, a natural population consisted of 116 genotypes wheat accessions were studied. Twenty one phenotypic traits were evaluated against drought stress (DS) and well-watered (WW) conditions. In addition, stem water soluble carbohydrates were analyzed at two different stages viz. flowering and grain filling under both water conditions. The main goal of this research is focused on detection of significant associations between microsatellite markers (SSR) and investigated traits. A general linear model (GLM) was applied to estimate marker-trait associations. The major results are as follows:1. The phenotypic traits were less affected by DS with high heritability estimates. High heritability were recorded for SP, SL, PH, PL, LSIT, LIBSIT, GYP and TGW under DS and WW. These characters can be used as the genetic parameters for the improvement and selection of high yielding genotypes in both environments. Correlation coefficient values of plant traits helps in estimating the degree of relationship which could be used for predicting the response of yield in wheat crop. Yield and yield components are correlated with each other under both conditions and the values of both environments are close. The positive correlation among the yield contributing traits suggested that these characters are important for direct selection of high yielding genotypes.2. The SWSC content found more in grain filling than flowering stage under DS. SWSCG exhibited significant correlation with other traits such as AESWSC, GFEL and TGWM in DS. It indicated that accumulation of SWSC increased the grain filling efficiency at the later stages and that contributed to the heavier grains in term of TGW. It is suggested that the WSC could play an important role for grain filling especially under DS. Broad sense heritability for SWSCG was high under drought stress.3. Moreover,17 MTAs were identified in irrigated and drought stress condition. The present study revealed most of the markers were identified for the traits reported as first time such as Xgwm 293, Xgwm 415, Xgwm 304, Xwmc 25, Xgwm 382, Xgwm 285, Xbarc 164, Xbarc 148 and Xwmc 432. Four favorable alleles were identified in current study under both water environments. One was found in DS while rest of them detected in WW condition. Under DS, Xbarc 78 on chromosome 4A had favorable effect for PH. Xgwm 25 (2D), Xbarc 78 (4A) and Xgwm 165 (4B) were considered as favorable alleles for GY, GYP and PH in WW condition. SSR markers which explained significant level of phenotypic variability for chosen traits could be valuable markers for selection of genotypes in wheat breeding programs through marker-assisted selection.