Effect of Water Stress on Rapeseed Cultivars Using Morpho-Physiological Traits and Their Relations with ISSR Markers

Abstract To study the effect of water stress in rapeseed cultivars at the seedling stage, 10 rapeseed cultivars were evaluated at three irrigation levels [normal irrigation (control) and irrigation after depletion of 60 and 85% of available soil water]. Analysis of variance showed considerable variation among cultivars. Water stress reduced all of the studied morphological characteristics, especially shoot and root dry weight, root volume and increased chlorophyll content and chlorophyll fluorescence. Cluster analysis at three levels of irrigation regime, assigned cultivars in different groups. Cultivars Licord, Opera and SLM043 were grouped together and showed higher average for all traits compared with other cultivars at all of the irrigation conditions. ISSR analysis using 11 primers produced 54 polymorphic bandsin the studied cultivars. Mean PIC and MI of all primers were 0.21 and 1.03, respectively. Cluster analysis based on molecular data using Nei's genetic distance assigned the cultivars into three clusters. Associations between molecular markers and morpho-physiological traits, were assessed by stepwise multiple regression analysis at different stress levels. The highest amount of variation contributed by ISSR markers belonged to relative leaf water content (78%) at non-stress condition, to root/shoot index (66%) at moderate stress condition and to root length (53%) at severe stress condition.