effects of sowing dates, irrigation intervals and cultivars on sugar beet root rot disease management and its quality and quantity yields

to study the effects of sowing dates, irrigation intervals and different cultivars on sugar beet root rot disease management and its quality and quantity yields, an experiment was conducted in a split- factorial based on randomized complete block design with four replications in the field of sugar factory jame. two irrigation intervals: eight days and 16 days were allocated in main plots, and different factorial arrangements of planting dates: 15 march, 15 april, 15 may, 15 june, and two cultivars dortea and jolgeh as resistant and susceptible to root rot disease were randomized in sub plots. the results indicated that irrigation intervals, planting dates and cultivars had positive significant effects on root and sugar yields at the 5% of probability level, while no significant effect was observed on sugar content. based on the results, root and sugar yields decreased and sugar content increased in late sowing dates (15 april). the area under the disease progress curve (audpc), was higher in the second year, comparing to the first year. no significant effect was observed on the audpc for irrigation and cultivars levels. as a result, resistant sugar beet cultivars can be recommended inearly sowing date, while susceptible cultivars is suitable in delay planting dates.