Journal of Crop Breeding

This study was conducted to evaluate the drought tolerance of new sugar beet monogerm hybrids. In order to select promising drought tolerant hybrids, two separate field experiments were conducted based on a randomized complete block design (RCBD) with four replications on 25 genotypes of sugar beet (23 new monogerm hybrids and two tolerant and normal controls) at Motahari Research Station, Kamal Shahr, Karaj, in 2012. Irrigation was done routinely up to the thinning and weeding stage. Subsequent irrigations were done after 90 mm and 200 mm evaporation from the class A evaporation pan in non-stress and stress conditions, respectively. The measured traits included root yield, sugar content, sugar yield, sodium content, potassium content, alpha-amino nitrogen content, alkalinity, molasses sugar, white sugar yield and extraction coefficient of sugar. Analysis of variance showed that there was a significant difference between genotypes for all of the traits under drought stress. According to the results of the stepwise regression analysis, more than 99 percent of white sugar yield variation was explained by root yield, sugar content, sodium content and potassium content in drought stress conditions. Also, according to the results of the cluster analysis, the genotypes were classified in four groups under drought stress condition among which the first group including the genotypes 25, 20 and 3 were identified as superior group in terms of yield and quality. Finally, the hybrids 20, 3, 8, 18, 7, 13 and 19, which were superior in terms of stress tolerance index (STI) and also in terms of yield traits in stress condition, were introduced as the most drought tolerant hybrids.