Effect of irrigation crop level and potassium fertilization on cultivar carignane vines 1. degree of water stress and effect on growth and yield
Kliewer, W.M.; Freeman, B.M.; Hossom, C.
American Journal of Enology and Viticulture 34(3): 186-196
ISSN/ISBN: 0002-9254 Accession: 005249022
The influence of 2 irrigation regimes (none and frequent), 2 levels of K fertilization (0 and 2.2 kg potassium sulfate per vine per year) and 2 crop levels (not thinned and cluster thinned to 1 per shoot) on growth and yield of field grown 'Carignane' vines was studied at Davis [California, USA] over a period of 3 yr (1979 to 1981). Irrigation increased yields by an average of 25.6%, whereas cluster thinning reduced yields by 21.5%, over a period of 3 yr. K fertilization reduced yields slightly, but no significant reduction was detected in either cluster number or cluster weight compared to no K fertilization. Irrigation and crop thinning increased both berry weight and berry number per cluster compared to no irrigation and no crop thinning, respectively. The rate of shoot elongation was reduced by water stress before any differences were detected in predawn leaf water potential. Water stress had no effect on the number of primary leaves produced per shoot or growth of leaves at nodes 10 and 17, counted from the shoot base. On a mild day with maximum temperature of 30.5.degree. C and minimum air water potential of -143 MPa [mega pascals] stomatal, conductance of irrigated vines increased to maximum of 6.1 mm s-1 at 1600 h. However, stomatal conductance for the nonirrigated vines reached a maximum of 4.6 mm s-1 at 1000 h, and then declined as the stomata began to close.