THE EFFECT OF ROOTSTOCK AND APPLIED WATER ON VINE WATER STATUS AND GAS EXCHANGE OF CABERNET SAUVIGNON

The effects of three rootstocks (5C, 110R and 3309C) and four irrigation treatments on leaf water potential and gas exchange of Cabernet Sauvignon grown in the Napa Valley of California were investigated during the 1996 growing season.
The irrigation treatments were fractions (0.5, 0.75, 1.0 and 1.5) of estimated full vineyard evapotranspiration (ET_c). Estimated full ET_c was determined by multiplying a crop coefficient developed in the Napa Valley with daily potential ET. Irrigations commenced the first week of July with water applications occurring once a week.
The crop coefficient increased from 0.45 the first week in July to 0.7 just prior to harvest (September 12). The greatest amount of applied water for the 1.0 irrigation treatment prior to harvest was 64 liters vine^-1 week^-1, the first week in September.
There were significant (p < 0.05) differences in both pre-dawn and midday measurements of leaf water potential (₁) as a function of irrigation treatments towards the end of summer.
There were no significant differences in ₁ among rootstocks.
Midday measures of net CO₂ assimilation and stomatal conductance were significantly greater for the 1.0 and 1.5 irrigation treatments compared to the 0.5 and 0.75 treatments.
Cabernet Sauvignon grafted onto the 5C rootstock had greater yields when compared to the other two rootstocks.
The results indicate that while irrigation amounts affected vine water status the first year of this study it was the rootstock that significantly affected fruit composition and vine productivity.

V International Symposium on Grapevine Physiology

I. Abu-Hilal, G. Collesano, Larry E. Williams

evapotranspiration, leaf water potential, net CO₂ assimilation rate, Vitis vinifera L.

https://doi.org/10.17660/ActaHortic.2000.526.13