Effect of Pruning and Nitrogen Fertilizer Levels and Their Interaction on Nitrogen Content of Leaves and its Variation with Time for Two Grape Cultivars Al-Halwani and Al-Kamali (Vitis vinifera L.)

摘要

This study was conducted to find the best level of pruning and nitrogen fertilizer on nitrogen content in leaves during different stages of growth for two kinds of grapes Al-Halwani and Al-Kamali (vitis vinifera L.). Four levels of pruning were used that is 100, 120, 140, 160 node/vine and four levels of nitrogen fertilizer that is 27, 54, 81, 108 kg/D. Nitrogen percentage in leaves was affected significantly by pruning levels for the two kinds and for the two seasons of the experiment during the first measuring period (1/5). The highest percentage was found in pruning levels 100, 120 node/vine. The fourth level of fertilizer (108 kg/D.) affected significantly the percentage for Al-Kamali during the first season for the first measurement period (1/5) only. The results indicated that the interaction affected the nitrogen percentage in leaves significantly. The pruning level 100 node/vine and 81, 108 kg/D nitrogen levels show the highest level of nitrogen content in leaves during 1993 season for bothkinds, while 100, 120 node/vine level for the same nitrogen level in 1994 season for Al-Kamali only. In general, the results indicated that nitrogen content in leaves was changed according to measurement period, the nitrogen percentage in leaves was high in the first measurement. This percentage has decreased at the beginning of the sixth month and then it was somehow stable. Afterwards, the percentage decreased and this decrease continued until harvesting.