Influence of timing of nitrogen fertilizer application on grapevines in the San Joaquin Valley.
Peacock, W. L.; Christensen, L. P.; Hirschfelt, D. J.;
American Journal of Enology and Viticulture Year: 1991 Vol: 42 Issue: 4 Pages: 322-326 Ref: 23 ref.
1991
บทคัดย่อ
In trials in 4 mature, furrow-irrigated vineyards (cultivars Thompson Seedless and Flame Seedless) in the San Joaquin Valley, the objective was to evaluate the effects of summer or late Sep. N fertilizer applications on N utilization, vine response and fruit development. Traditionally in this area N has been applied to soil in late winter or early spring and information on the effect of fertilizer application during the growing season is lacking. Ammonium nitrate (50 kg N/ha) was applied to the soil either at budbreak, fruit set, veraison, in late Sep. (postharvest), or in split applications (fruit set + late Sep.) and compared with an unfertilized control over 3 years. N applied to Thompson Seedless at budbreak increased nitrate levels in petioles sampled at bloom by 26% and was less effective than N applied at veraison or in late Sep. which resulted in a 54% and 67% increase, respectively. N applied at fruit set increased nitrate levels by 37%, intermediate between levels for the budbreak and veraison timings. Uptake and utilization of soil-applied N was slower during the period from budbreak to bloom compared with the period from fruit set to veraison. The inorganic N levels of Flame Seedless petioles were not affected by N fertilizer application. Total N concentration of fruit juice and arginine concentrations in dormant canes or spurs remained unchanged by fertilizer application in both cultivars. Delaying fertilizer application did not affect cane fruitfulness and stimulation of late season shoot growth was not observed. Fertilizer application, regardless of timing, reduced content of soluble solids; however, berry weight, titratable acidity and pH were not affected. This study indicates that N applied during fruit set, veraison, late Sep. or in split applications is compatible with vine growth and fruit development.