Effects of Soil Moisture Content in Early Autumn on the Growth of Satsuma Mandarin Trees

Abstract

1) The experiment was made in early autumn (September) on the effects of fruiting and different soil moisture condition on the dry matter yield in Satsuma mandarin trees.2) The dry weight and total carbohydrate content of 3-year-old stems and feeder roots was higher when the trees were def ruited in early autumn than those of the untreated fruiting trees. Furthermore, in some fruiting trees treated with the plot of ringing on their trunk, higher dry weight and total carbohydrate content in their peel and pulp was observed.3) The dry weight of various organs did not show significant differences between the trees grown in low moisture condition (pF 3.0-3.5) and those grown in medium moisture condition (pF 2.0-2.5) during the 30 days period of investigation.4) When the trees grown in the low moisture conn dition during 30 days period in early autumn were transferred to the medium moisture condition, two months later, the rate of dry matter of new-leaves, old-leaves and fruits of the plants became higher than those of the trees placed in the medium moisture condition throughout the period.5) The dry weight of fruits and total sugar and total carbohydrate content of fruits did not show significant differences although the plants were treated in two main different soil moisture conditions, but the rate of dry matter of fruits became higher in reduced soil moisture content. Therefore, the fruits of high quality on the trees grown in the low moisture condition appeared to result from reduced absorption of water by the fruits. In the pulp of the trees placed in the low moisture condition, higher fructose and glucose contents and lower sucrose contents were observed.6) The translocation of photosynthates into the fruits appeared to be unaffected by the low moisture condition during the 30 days period of investigation in early autumn.