Author
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Shellie, Krista |
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Submitted to: American Journal of Enology and Viticulture
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/20/2006 Publication Date: 12/1/2006 Citation: Shellie, K. 2006. Vine and berry response of Merlot (Vitis Vinifera L.) to differential water stress. American Journal of Enology and Viticulture. 57(4):514-518. Interpretive Summary: Little information has been published on the response of Merlot grapevines to water stress under field conditions and none is available on their response to deficit irrigation under the climatic conditions and soils of southwestern Idaho. The objective of this research was to measure vine and berry response of Merlot grown under differing severity of vine water stress during berry development. Own-rooted Merlot vines were exposed to deficit irrigation treatments in a 3-year field trial conducted in the warm, arid Western Snake River Plain of southwestern Idaho. Vines were drip irrigated weekly with 100, 70, or 35% of their estimated required water. A fourth irrigation regime provided 35% of water needs until berries changed from green to purple, and then 70% of estimated needs until harvest. Vine water stress was monitored weekly and corresponded with amount of irrigation. Decline in main shoot growth, berry size, cluster weight, yield, trunk growth, cluster number, and berry titratable acidity corresponded with a decline in vine water status. Increasing irrigation amount from 35 to 70% at veraison produced the same yield and fruit quality as 70%, but increased water savings by about 25%. Technical Abstract: Own-rooted Merlot vines were exposed to deficit irrigation treatments in a 3-year field trial conducted in the warm, arid Western Snake River Plain of southwestern Idaho. Vines were drip irrigated weekly, from fruit set until harvest, with 100, 70, or 35% of their estimated crop evapotranspiration (ETc) requirements. A fourth irrigation regime provided 35% ETc until veraison followed by 70% ETc until harvest. Average midday leaf water potential differed among irrigation regimes and ranged from -0.9 to -1.7 MPa throughout the season, with a 0.3 to 0.5 MPa difference between the 35 and 100% ETc treatment. Decline in main shoot growth, berry size, cluster weight, yield, trunk growth, cluster number, and berry titratable acidity corresponded with a decline in leaf water potential. Increasing irrigation from 35 to 70% ETc at veraison produced the same yield and fruit quality as 70% ETc, but increased water savings by about 25%. |
