Seasonal Carbohydrate Changes in the Leaves of Some Satsuma Cultivars on Different Rootstocks

The seasonal changes of carbohydrate content were monitored in the leaves of 'Okitsu', 'Clausellina', and 'Silverhill' satsuma cultivars budded on the sour orange (Citrus aurantium L. var. Yerli), Carrizo and Troyer citranges (Poncirus trifoliata Raf. x Citrus sinensis Osb. var. Troyer and Carrizo) during the 2010 and 2011 seasons. The seasonal changing trends of leaf soluble sugar contents of 3 satsuma cultivars budded on different rootstocks were similar. The sucrose was the most abundant soluble sugar. Carbohydrate contents had a maximum level at dormant period, and remained at low level during summer. In this period, the sharp decrease in leaf total carbohydrate concentration of 'Okitsu', 'Clausellina' and 'Silverhill' occurred in April with a rate of 27.9%, 22.6% and 21.0%, respectively. Accumulation of carbohydrate in leaves generally started after mid summer and continued until the end of year. The rootstocks were found to be not significant for total soluble sugar, starch and total carbohydrate concentration in most of the months. The cultivars had a significant effect on carbohydrate fractions of leaves compared to rootstocks. The scion-rootstock combination was significant on total carbohydrate concentration of leaves in all months investigated.