Effect of varying nitrogen and phosphate supply rate by drip irrigation in grape [Vitis] rhizosphere control culture on vine growth, fruit quality, and yield

Rhizosphere control culture of grapes was investigated to develop a technology for producing a large amount of high quality fruit at an earlier time. The effect of nitrogen and phosphate supply rate on vine growth, fruit quality, and yield has been investigated by setting a harvest goal of two tons per ten acres. The concentration of phosphate in soil rinsing water was higher when phosphate fertilizer was supplied at a rate of sixty grams per vine than it was at thirty grams per vine. No difference was observed between these two supply rates in terms of vine growth, fruit quality, and yield. Accordingly, it has been determined that thirty grams per vine per year is an appropriate supply rate for phosphate fertilizer. When nitrogen was supplied at zero grams per vine, the flower shatter off phenomenon occurred, and berry number and cluster weight decreased, resulting in a marked decline in yield. Supplying nitrogen at more than ten grams per vine resulted in no significant difference in berry number, cluster weight, and berry weight in the second year of planting, with a yield of more than 1.8 tons per 10 acres. However, when nitrogen was supplied at ten grams per vine, leaf color at the base of vines declined after the coloring period, resulting in leaf shedding, and so it is suggested that twenty grams per vine is an appropriate nitrogen supply rate in the second year of planting. After the third year of planting, when nitrogen was supplied at zero to twenty grams per vine, cluster weight declined year by year and yield tended to decrease. If a large yield is to be guaranteed, supplying nitrogen at twenty grams per vine seemed to be falling short. When nitrogen was supplied at sixty grams per vine, the largest rate among our trials, the characteristics influencing yield, such as berry number, berry weight, and cluster weight, remained high even after the third year of planting. In contrast, when nitrogen was supplied at twenty or thirty grams per vine berry number and cluster weight declined, resulting in low yield. Taken together, it has been determined that the appropriate supply rate of nitrogen for this specific culture method would be sixty grams per vine and thirty kilograms per ten acres.