الفهرس 
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Abstract
This study consisted of the three following experiments: the first experiment was carried out in the laboratory of Department of Genetics Fac. of Agric. Minia Univ. This experiment aimed to improve the efficiency of Azotobacter vinelandii bacteria wild type for nitrogen fixation through exposing to Ultra violet irradiation to induce different auxotrophic mutants. The cells were exposed to (mutagenic agent) UV-light for 1.0, 2.0, 3.0, 4.0 and 5.0 minutes after five days of incubation on 30°C, the numbers and percentages of Azotobacter vinelandii survival after treatment with UV and bacterial growth were recorded as well as the percentages and No. of characterized single mutants resulted by different time exposure to UV irradiation in Azotobacter vinelandii. The second experiment was established in a nursery situated at El-Minia Fac. of Afric. During 2004 and 2005 seasons on one-year old Banaty grapevines transplants in continuation for the laboratory experiments. This part was executed to explore the effects of the fifteen mutants produced from exposing Azotobacter vinelandii in combination with four levels of mineral nitrogen namely 0.0, 0.5, 1.0 and 2.0 g ammonium nitrate (33.5%) on growth characters as well as percentages
Results showed that the five supreme induced mutants responsible for enhancing the efficiency of N fixation, growth characters and fruiting of Banaty seedless grapevines were Prolineless, Thymineless, Lysineless, Arginineless 2 and Histidineless 2, in ascending order. The best proportion of mineral N applied with biofertilizers was 50% of the recommended rate of N. Putting in our consideration the yield and fruit quality, fertilizing Banaty grapevines with N at 100 g N/vine through the Azotobacter vinelandii mutant Histidineless 2 at 100 g/vine plus 150g ammonium nitrate/vine proved to be very effective for obtaining high and better fruit quality.