study of sugar beet growth pattern in hamedan

the current study was carried out to examine sugar beet growth pattern in climatic conditions of hamedan, iran and to recognize the factors affecting its quantity and quality as well as the physiological indices. two sowing date experiments were conducted on the basis of a randomized complete block design with four replications and 11 harvests. the plots were destructively sampled and the growth was analyzed by regression method on the basis of the variations of leaf area index, leaf dry weight and total dry weight which are the basis of growth analysis. results revealed that the maximum crop growth rate of the earlier sowing date reached to 20.2 and 23.3 g.m-2.d-1 90 days after planting in 2002 and 2003, respectively. in the second sowing date, maximum crop growth rate reached to 29.5 and 25.0 g.m-2.d-1 110 and 96 days after planting in 2002 and 2003, respectively. maximum leaf area index of the earlier sowing date was obtained about three months after planting approximately concurrent with the realization of maximum crop growth rate and reached to 2.5 in 2002 and to 2.6 in 2003, but it started to slowly decrease at later growth period. relative growth rate was the highest at the early growth period and linearly decreased during growth period. net assimilation rate firstly increased slowly, but as the leaves grew and shaded each other, it started to decrease. the highest root growth rate in the earlier sowing date reached to 10.1 and 20.0 g.m-2.d-1 94 and 92 days after planting in 2002 and 2003, respectively. the highest root growth rate in the second sowing date reached to 14.0 and 17.3 g.m-2.d-1 108 and 95 days after planting in 2002 and 2003, respectively. in total, root potential yield was considerably higher in the earlier than in the delayed sowing date under climatic conditions of hamedan in both years. the sugar beet growth pattern-related physiological indices were greatly consistent with crop yield potential during growing season. therefore, given the climate changes and global warming, sugar beet sowing in the earliest possible date in hamedan is recommended in terms of physiological indices and yield.