Abstract
The relationships between volumetric water concentration in branches (θbranch) measured by time domain reflectometry (TDR) and soil moisture, potential evaporation, leaf water potential (LWP) and fruit quality were investigated in order to evaluate the efficiency of θbranch for optimal water management to obtain high quality fruit. The θbranch at the base of the trunk began to increase in April, reaching the highest value in July, then gradually decreased and reached the lowest value in mid-October including that during the harvesting period. After harvesting, the θbranch increased slightly, and then became stable in winter. The decrease in θbranch from summer until harvesting and the increase after harvesting were related to the soil moisture. The seasonal changes in θbranch of the trees as long as the LWP was controlled around -1 MPa corresponded to the potential evaporation. Moreover, it was found that water stress condition was reflected in changes in θbranch, LWP, and fruits quality. Although the relationship between θbranch and LWP was unclear, our results suggested that θbranch measured by TDR would be a useful indicator for water management in Satsuma mandarin orchards.
