PJB-2018-456
EFFECT OF INCREASING THE WATER TRANSPORT DISTANCE ON TYLOSE DEVELOPMENT AND SAP FLOW OF GREENHOUSE GROWN Meili GRAPEVINE
XIANHUA ZHAO
Abstract
Grape pruning may lead not only to some physical damages to the xylem vessels but also to the tylose blockage in these vessels. However, there is little information on vessel lumens blockage by tylose decreasing the original capability of sap flow transportation. In present studies, to elucidate the effect of tyloses on both water transport during xylem development and variations in hydraulic conductance with increasing the distance of water transport, we evaluated shoots of three different-shaped vines, based on observation of tylose developments and sap flow measurements. The study showed that, for different-shaped vines, sap flow transport distance is significantly associated with quantity of tyloses. Vessels of Cordon-training (CT) vines have the largest percentage of partly and completely blocked vessels among three different-shaped vines, up to 65.4% and 33.2% respectively. For renewal Crawled Cordon Training (rCCT) and perennial Crawled Cordon Training (pCCT) vines, shoots of perennial branches (pCCT) have a larger percentage of partly and completely blocked vessels (39.7% and 16.7% respectively) than shoot of current-year shoots (rCCT vines, 35.6% and 9.3% respectively). Sap flow rates and sap flow transport distances had a negative correlation for sap flow rates of same-shaped vines. In addition, sap flow rates and sap flow transport distances (namely, number of nodes) and/or quantity of tyloses varied during different-shaped vines. Overall, vessels with few tyloses showed significantly higher values of hydraulic conductance than vessels were completely or partially occluded by much more tyloses.
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