Publication Date:
2012-03-29
Description:
Vineyards were planted in the arid region of northwest China to meet the local economic strategy while reducing agricultural water use. Sap flow, environmental variables, a plant characteristic (sapwood-to-leaf area ratio, A s / A l ) and a canopy characteristic (leaf area index, L ) were measured in a vineyard in the region during the growing season of 2009, and hourly canopy stomatal conductance ( G si ) was estimated for individual vines to quantify the relationships between G si and these variables. After accounting for the effects of vapor pressure deficit ( D ) and solar radiation ( R s ) on G si , much of the remaining variation of reference G si ( G siR ) was driven by that of leaf-specific hydraulic conductivity, which in turn was driven by that of A s / A l . After accounting for that effect on G siR , appreciable temporal variation remained in the decline rate of G siR with decreasing vineyard-averaged relative extractable soil water ( E ). This variation was related to the differential decline of E near each monitored vine, decreasing faster between irrigation events near vines where L was greater, thus adding to the spatiotemporal variation of G siR observed in the vineyard. We also found that the vines showed isohydric-like behavior when E was low, but switched to anisohydric-like behavior with increasing E . Modeled E and associated G s of a canopy with even L (1.9 m 2 m –2 ) were greater than that of the same average L but split between the lowest and highest L observed along sections of rows in the vineyard (1.2 and 2.6 m 2 m –2 ) by 6 and 12%, respectively. Our results suggest that managing sectional L near the average, rather than allowing a wide variation, can reduce soil water depletion, maintaining G s higher, thus potentially enhancing yield.
Print ISSN:
0829-318X
Electronic ISSN:
1758-4469
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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