Evaluation of root yield and sugar content of new sugar beet hybrids under water deficit and optimum irrigation

To determine sugar content and root yield variation of new sugar beet hybrids under different irrigation levels, an experiment was carried out at Zarghan Agricultural Research Station ofFars Agricultural and Natural Resources Research Center, Shiraz, Iran. The study was conducted as split block based on a randomized complete block design with three replications for two years, 2009-10, using line source sprinkler system. The treatments consisted of six cultivars including 28064, 28058, 28928, Zarghan, Jaam, and Rasoul (susceptible check) in main plots, and three irrigation levels viz. control, medium stress, and severe stress in subplots. Irrigation levels were set according to the distance from lateral tube and 4 m distance was considered for imposition of irrigation levels. Combined analysis results showed that hybrid 28928 had the highest root yield. It also showed higher than average yield stability in both optimum and water deficit conditions. Zarghan cultivar had lower yield in water deficicit condition while in normal irrigation the result was opposite. Regression analysis showed a quadratic equation between sugar content and water consumption so that sugar content was decreased in the range of about 400-900 mm irrigation but increased in less than 400 mm and more than 900 mm. In spite of increasing sugar content, water deficicit cannot be recommended for sugar production owing to yield reduction.. Considering the positive response of root yield to water use, 1100 mm irrigation level is suggested for increasing both root yield and sugar content.