EFFECT OF SOME LEGUME COVER CROPS AND ORGANIC FERTILIZER ON PETIOLE NUTRIENT CONTENT, PRODUCTIVITY AND FRUIT COMPOSITION OF 'THOMPSON SEEDLESS' GRAPEVINES

This investigation was undertaken for three seasons 2007, 2008 and 2009 on seven-year-old ‘Thompson seedless’ grapevine grown in clay loam soil in El-Mansoura Horticultural Research Station, Horticulture Research Institute. Treatments included in the experiment were management of on-rows (cultivated vs. perennial legume cover crops) and nitrogen fertilization (compost vs. mineral fertilizer). Leaf area, fertility, vine nutritional status, yield, fruit composition and pruning weight are monitored each season (2007-2009). Conventional cultural practices (cultivation and mineral fertilizer) produced the highest yield, cluster weight, fruit weight and diameter, TSS, TSS/acid ratio in the first season. There were no significant differences found in the third season because the legume cover crop had become fully established. Cover crop with mineral fertilizer treatment increased leaf area, pruning weight and mineral content in leaf petioles in the first season, whereas, cover crop and compost treatment obtained the best results in the third season. The highest nitrate and nitrite residues in the berries were observed with mineral fertilization, yet the lowest values were obtained from compost with peas or clover as cover crop treatments. We conclude that using compost with peas or clover as cover crop treatments, reduces the amount of required mineral nitrogen fertilizer and produces healthy fruits with a reduction in environmental pollution.