PS 31-2 - Effects of root-zone deficit irrigation on crop growth, fruit yield, and agroecosystem stability: using the wine grapevine Cabernet Sauvignon as a model

Wednesday, August 9, 2017
Exhibit Hall, Oregon Convention Center
Xiaochi Ma1, Pete W. Jacoby1, Alexis N. Torp2 and Lindsey M. Mongan3, (1)Crop and Soil Sciences, Washington State University, Pullman, WA, (2)Horticulture, Washington State University, Pullman, WA, (3)Viticulture and Enology, Washington State University, Pullman, WA

Water available for crop irrigation is often limited owing to multiple competing demands from the public as well as from changing climatic patterns. Conventional surface irrigation may result in moisture loss associated with surface evaporation, as well as from weeds which disturb agroecosystem stability through competition with crops and resultant herbicide usage. Delivering limited water supply directly into deep root zone by using subsurface micro-irrigation might be a good strategy to reduce these challenges. By using the grapevine Cabernet Sauvignonas a model crop, we conducted both greenhouse and field experiments to investigate the effects of deficient root-zone irrigation on crop growth and production. We employed 3 watering rates (full, median, low) and delivered the water at 3 depths (0, 30, 60cm from the soil surface) to observe differences of root growth and distribution, periodically measure belowground and aboveground biomass, and calculate fruit yield under each treatment. We will also conduct an ecological experiment to evaluate the effects of root-zone deficit irrigation on weeds colonization and competition.


Vines receiving the full watering rate accumulated biomass faster than vines in deficient watering rates during the middle growing season (P < 0.05). During the late growing season, biomass accumulation for vines in median and full watering rates became similar, but both of them were still significantly higher than vines in low watering rate (P < 0.05). Additionally, the ratio of belowground to aboveground biomass for vines in median watering rate was significantly higher than the ratios for vines in full and low watering rates (P < 0.05). Roots were found to develop deeper into the soil profile under water stress, which could be considered a survival strategy that helps plants access water during extended drought in deeper soils. This strategy might help create “an upper dry zone” that will restrict weeds growth. By using direct root-zone irrigation, water use efficiency of grapevine was increased, and fruit production was affected both by watering rate (P < 0.05) and climatic shift. Based on our current findings, deficient root-zone irrigation might be a preferred method to save water, and sustain agroecosystem for reliable levels of crop production.