Evaluation of drought tolerance criteria in sugar beet genotypes

In order to evaluate the best drought resistance indices in sugar beet genotypes, an experiment was conducted in 2002 using a split- plot design within randomized complete block design with three replications at the Research Farm, Shiraz-Zarghan. The main plots consisted of three Irrigated regimes: non stress, 75% (mid stress) and 50% (intense stress) non stress and the ten genotypes as the sub factor. Water stress was initiated at about six-leaved stage, and the stress was continued throughout the growing season. Drought resistance indices consisting of stress susceptibility index (SSI), stress tolerance index (STI), mean productivity (MP), geometric mean productivity (GMP), stress tolerance (TOL) and harmonic mean (Harm), were evaluated for white sugar yield in stress and non-stress conditions. The results showed that drought stress reduced white sugar yield. Results from calculating drought toletance indices, correlation among indices and white sugar yield in stress and non-stress conditions showed that STI, Harm, GMP and MP indices, effectively distinguished genotypes with high yield in both conditions and were determined as the best drought tolerance indices. Because of high correlation between STI and the other indices, it's significance is more than the other ones. Finally, 7221-I-79, BP-Mashhad and control-Rasool genotypes were determined as the genotypes that have a high potential white sugar yield in both environments.