TY - JOUR T1 - Effect of Irrigation, Crop Level and Potassium Fertilization on Carignane Vines. I. Degree of Water Stress and Effect on Growth and Yield JF - American Journal of Enology and Viticulture JO - Am J Enol Vitic. SP - 186 LP - 196 DO - 10.5344/ajev.1983.34.3.186 VL - 34 IS - 3 AU - W. Mark Kliewer AU - Brian M. Freeman AU - Charles Hosssom Y1 - 1983/01/01 UR - http://www.ajevonline.org/content/34/3/186.abstract N2 - The influence of two irrigation regimes (none and frequent), two levels of K fertilization (0 and 2.2 kg potassium sulphate per vine per year) and two crop levels (not thinned and cluster thinned to one per shoot) on growth and yield of field grown Carignane vines was studied at Davis over a period of three years (1979 to 1981). Irrigation increased yields by an average of 25.6%, whereas cluster thinning reduced yields by 21.5%, over a period of three years. Potassium 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°C and minimum air water potential of -143 MPa, stomatal conductance of irrigated vines increased to a maximum of 6.1 mm sec-1 at 1600 hr. However, stomatal conductance for the nonirrigated vines reached a maximum of 4.6 mm sec-1 at 1000 hr, and then declined as the stomata began to close. ER -