Recent Trends In Thompson Seedless Grapevine Fertilization

Absttact

This study was conducted during the two seasons of 2000 and 2001 to study the effect of different levels of mineral nitrogen fertilization and different biofertilizer levels on vegetative growth, yield (quantity and quality) and seasonal changes of N, P and K content in Thompson seedless grapevines.
The main objective of this investigation was to study the effect of using different levels of biofertilizers including N-fixing bacteria (Azotobacter chroococcum and Azospirillum brasilense) and mineral nitrogenous fertilizers (Ammonium nitrate 33.5% N and ammonium sulfate 21.5% N) on vegetative growth, cluster and berries physical and chemical characteristics and yield of Thompson seedless grape. NPK behaviour during different stages of grapevine growing season as well as dehydrogenase enzyme activity in the soil were also studied. So, this investigation was carried out aiming to reduce the amount of mineral N fertilizer applied to the soil. Such reduction could decrease environmental pollution which is harmful for human, soil and water and produce healthy yield of a high demand for exportation besides minimize the cost of production and , in turn, increase the net income of vineyards.

Obtained results recorded that nitrogen fertilizer applied to Thompson seedless grapevines at an adequate amount (60 or 40 N unit and per feddan) have a positive effect on growth (leaves area and chlorophyll contents), yield and most of physical and chemical characteristics measured on both clusters and berries. This effect was true except for berries firmness and adherence, which they were increased under low level of nitrogen. The obtained results also indicated that the applied biofertilizer at 9.9 g biofertilizer had a benefit effect on vine growth and yield as well as most cluster and berry qualities. As for the interaction treatments of N and biofertilizer, the concerned results pointed to that 60 N unit + 9.9 gm biofertilizer was the best combination treatment. followed by treatment of 40 N unit + 9.9 g biofertilizer.