بررسي برخي صفات كمي و كيفي ژنوتيپ هاي اميدبخش چغندر قند در شرايط تنش خشكي

Study of quantitative and qualitative traits of promising sugar beet genotypes under drought stress conditions

This experiment was conducted to evaluate eight new sugar beet genotypes with different drought tolerance responses to three irrigation schemes (including normal irrigation and early season and continuous stressed) in Motahari Research Station of Sugar Beet Seed Institute (SBSI), Karaj, Iran during 2005-2006. The study was accomplished in a split plot design (irrigation schemes and genotypes as main and sub-plots, respectively) based on randomized complete blocks design with four replications. Results showed that the normal irrigation (irrigation after 80 mm evaporation from class A pan) and early season stress (three times irrigation for plant establishment, no irrigation until 500 mm evaporation from class A pan, and then regular irrigation up to the end of growth period) were in the same statistical group for root yield, white sugar yield and root/shoot ratio. But, early season stress increased water use efficiency (WUE) by 35 % compared with the normal irrigation. Maximum sugar content, white sugar yield, WUE and stress tolerance index (STI) were obtained for 7112, BP Karaj and RS003 genotypes and minimum values for 7221-II. Compared with 7221-II, 7221-II*I13 had higher sugar content, white sugar yield, WUE and STI about 22, 49, 62 and 187 percent, respectively, and better yield stability than other genotypes under stress conditions. Our study results indicate that fodder beet germplasm with a high root production potential in drought conditions could be used in sugar beet breeding programs. Transfer of fodder beet root production character to sugar beet in drought conditions is likely to increase the efficiency of sugar beet breeding programs for drought tolerance.