Table grapes fertilization with nitrogen (N) potassium (K) and phosphorus (P)

Dr. Arnon Dag, Dr. Uri Yermiyahu Dr. Amnon Lichter, Dr. Etti Or, Mr. Eran Harcabi and Mr. Eyal Raban

Numerous environmental conditions and viticultural practices are known to alter the vine growth and productivity and grapes quality.  Key factors among these are climatic conditions (temperature, solar radiation, and humidity), grapevine cultivars and rootstocks used, irrigation, crop load, and canopy management practices. The impact of vine nutrient supply, particularly on productivity and quality parameters is less understood. There are some publications on the effect of nitrogen (N) and much less is known about how phosphorus (P) or potassium (K) may affect the vine performance. This is scarcity of information is especially prevalent in Israel; The few studies conducted so far didn’t lead to clear outcome, especially because of high storage of elements is soil prior to the experiments that mask the effect of fertilization treatment.

In the current study we plan to use an innovative growing system, which worked successfully in determining the fertilization requirements of olive, pomegranates and almond. In this system we grow the trees in containers in perlite media with full control of the nutritional elements arriving with the water. This approach allows as to get very rapidly information on the crop responses to the availability of macronutrients.  We will test two table grapes cultivar, the early bearing, green ‘Early Sweet’ and the late bearing, purple color, ‘Crimson’, which will be grown in 500-L containers filled with perlite. In each variety, we will test five levels of N (10, 20 ,70, 100 and 200 ppm), three levels of K (20, 100 and 200 ppm) and three levels of P (1, 10 and 20 ppm). We will follow the plants’ reproductive and vegetative growth, their physiological response, nutritional status (as determined by nutrients in leaves and petioles), fruit yield and quality. In quality parameters, we will give special emphasize to TSS in the early ‘Early Sweet’ and to the color of the skin in ‘Crimson’ (which is one of the major quality constrain of this variety).   We anticipate the results of this study to provide a solid understanding of the role of N, P and K fertilization in table grapes cultivation under intensive conditions