Rootstock Effects on Yield, Fruit Quality and Nutrition Status of "Early Sweet" Grape Fertilized with Varying levels of Nitrogen and Potassium

A TWO years study was carried out during two successive seasons (2017 and 2018) on seven years old Early Sweet grapevines budded on Freedom and Salt Creek rootstocks grown in sandy loam soil, spaced at 2 X 3 meters apart under a drip irrigation system in a private grapevines orchard located on Cairo-Alexandria desert road about 50 km from Cairo, Egypt. The main objective is to study the effect of nitrogen supported with potassium and two rootstocks salt Creek and Freedom as well as their combinations on yield and fruit quality properties of Early Sweet grape vine. The study was arranged in a split plot design, hence two rootstocks (Freedom and Salt creek) were occupied in the main plot, and the subplots were split by (N+K) application levels. Whereas, three levels of nitrogen (30, 40 and 50 kg /fed) as actual nitrogen were applied. Potassium levels were added at the ratio (1:1.5 and 1:2) from nitrogen level plus control treatment was (60kg N/fed+120kgK/fed). Obtained results showed that, fertilization with high rates of nitrogen reduced cluster weight, cluster length, and cluster width of “Early Sweet” Generally, Early Sweet grapevine grafted on Salt creek rootstock fertilized with 40kg N/fed plus 80kg K/fed proved to be the most efficient effect application on yield and fruit quality.