Evaluation of drought tolerance of sugar beet monogerm hybrids under in vitro condition using polyethylene glycol (PEG 6000)

The present study was designed to evaluate the drought tolerance of new sugar beet monogerm hybrids using polyethylene glycol 6000، under in vitro condition. The experiment was carried out as a factorial experiment based on completely randomized design with four replications in Sugar Beet Seed Institute، Karaj in 2013. 23 new sugar beet monogerm hybrids with two tolerant and normal controls were sowed in normal (osmotic potential at zero) and drought stress (-0. 7 Mpa) conditions. After six weeks، traits such as length of root and shoot، fresh and dry weight of root and shoot، seedling length، dry and fresh weight were measured. The analysis of variance showed that stress levels and interaction genotypes in stress were significant for all of the measured traits. The effect of genotype was also significant for all traits except root dry weight. According to the results of Cluster analysis with Ward method، hybrids were classified in three and four different groups، respectively، based on the measured traits under drought stress conditions that hybrids number two، 21، 22، three، 23 and 20 in normal conditions and hybrids number 13، four and three in stress conditions were identified as superior hybrids. Also was used of the stress tolerance index (STI) in order to compare the drought tolerance and the final screening tolerant hybrids and top and hybrids number 13، 22، 23، 21، seven، four، 20 and three were introduced as the most tolerant hybrids to drought stress at seedling stage that can be used in future breeding work by researchers.