Assessment of Possibility of Autumn Sowing of Sugar Beet in Alborz Province in Iran

Sugar beet is usually planted in spring in Alborz province and similar climatic conditions, and uses high irrigation water and suffers from the breakout of pests and diseases. The development of sugar beets cultivars for autumn sowing has become of interest of breeders due mainly to its much lower irrigation water requirement than spring sown sugar beet. The present research was aimed to explore the possibility of autumn sowing of sugar beet in Karaj and similar climatic conditions. Two sugar beet cultivars; Sharif (moderately resistant) and Vico (resistant), and three sowing dates; early-October, late-October and mid-November were evaluated as factorial arrangements in randomized complete block design with three replications at sugar beet research station, Karaj, Iran, in three growing seasons from 2014 to 2017. Most seedlings were killed by winter freezing in 2014 and 2016, however, sugar beet seedlings survived in 2015 winter and produced economic yield. Analysis of variance of data for the 2015-16 growing season showed that when sowing date delayed from early-October to late-October and mid-November, the bolting rate significantly decreased from 15.9% to 5.0% and 0.5%, respectively. However, the winter killing rate increased from 48.7% in early-October to 62.6% and 78.8% in the second and third sowing dates, respectively. Sowing date significantly (p < 0.01) affected root, sugar and white sugar yields. The highest root, sugar and white sugar yields (41.6, 6.5 and 4.3 tha-1, respectively) were produced in early-October, and the lowest were obtained from late-October and mid-November sowing dates. Cultivars did not differ significantly for root yield, but were significantly (p < 0.05) different for sugar and white sugar yield. The sugar and white sugar yield of cv. Vico (4.2 and 2.9 tha-1, respectively) was higher than cv. Sharif (3.4 and 2.2 tha-1, respectively). Cv. Sharif’ was more sensitive to delay in sowing date. In conclusion, considering limitation of water resources in Iran, the development of resistant cultivars to bolting and freezing may facilitate autumn sowing of sugar beet in Karaj and similar climatic conditions.