We have made substantial progress in understanding at least one mechanism involved in determining why grapevines achieve such high vigor in deep fertile soils, even when irrigation water is withheld. This mechanism can be generally defined as hydraulic redistribution and involves the passive movement of water from roots in moist soil zones, under the drip irrigation emitter or from groundwater, to roots in dry surface or subsurface soils outside the emitter zone. We achieved this result by labeling water with 2%deuterium oxide, D2O. We then applied the labeled water through a drip emitter on one side of each of three 5-7 yr-old 420A rootstocks (Vitis berlandieri X V. riparia). We extracted roots and soil from both the labeled side and the dry side of the vine. Using the quantity of isotope found in roots we estimated that nearly 6 to 8%of the water in roots on the dry side of the vine came from the labeled water in the emitter zone. This water was conducted through the grapevine trunk and into roots on the dry side almost immediately (36 h). These observations suggest that the establishment of an extensive root system may contribute to over vigorous vines more than any single physiological trait like nutrient absorption because total root system size probably has more to do with total capacity for nutrient and water absorption than any other single factor. Hydraulic redistribution probably allows vines to sustain roots even during adverse conditions for growth. We are proposing further experiments in this area.
/wp-content/uploads/2017/09/AFV-Header-Logo.png 0 0 AVF /wp-content/uploads/2017/09/AFV-Header-Logo.png AVF2002-10-17 11:17:582017-10-17 11:18:34Physiological Role of Rootstocks in Determining Grapevine Vigor