2019 Volume 57 Issue 1 Pages 1-7
This study investigated the effects of tree morphology, including the above-ground body to root biomass ratio and organ size, on the severity of drought stress in Meiwa kumquat to elucidate the relationship between the severity of drought stress and number of first-flush flowers. Leaf water potential gradually decreased during the treatment of soil water deficit (SWD), and was negatively correlated with the dry weight of the trunk & old branch of the trees which was positively correlated with the number of first-flush flowers. Although transpiration from the trunk surface was confirmed, its rate was approximately 1/6th of that from the leaf surface under non-stressed conditions. The transpiration rate of trunk remained unchanged during SWD treatment but that of the leaf rapidly decreased. Therefore, the severity of drought stress was possibly dependent on the size of the trunk and old branches that may determine the amount of transpired water under drought conditions. Consequently, it may be preferable to employ parameters that indicate water status inside the trunk or scaffold branches rather than water potential of the leaves to understand how SWD treatment increases the number of first-flush flowers.