Study of genetic variation for drought tolerance in sugar beet half-sib families

In order to evaluate the genetic variation of drought tolerance-related traits in sugar beet half-sib families, two experiments including 37 half-sib families were conducted under normal and drought stress conditions using a randomized complete block design with three replications at Agricultural Research Station of Miandoab, Iran in 2014. Based on the results, significant difference was observed between normal and drought conditions for root yield, white sugar yield, sugar yield, cell membrane stability (P < 0.01), and sugar content (P < 0.05). Significant difference was also observed among genotypes for root yield, sugar yield, K, cell membrane stability, water use efficiency (P < 0.01), white sugar yield, and chlorophyll index (P < 0.05). Genotype × environment interaction had significant effect (P < 0.01) on sugar content, Na, K, white sugar content, extraction coefficient of sugar, and molasses sugar. Drought stress significantly decreased root yield, sugar content, sugar yield, white sugar yield and cell membrane stability. Root yield and white sugar yield had 0.59 and 0.66 heritability under stress condition and 0.63 and 0.80 under normal condition, respectively. Under both conditions, white sugar yield had positive and significant correlation with root yield, sugar content, and extraction coefficient of sugar and negative and significant correlation with Na, K and molasses sugar. According to the path analysis results, under both conditions, sugar content, relative water content, and chlorophyll index had significant effect on white sugar yield. Finally, based on cluster analysis results, in both water treatments the genotypes were classified into three groups and genotype HSF-883 was selected as a superior genotype in terms of yield and quality under both conditions.