Abstract
The study was conducted at Research Field /Agriculture Research Station ,Zakho, North of Iraq during 2005 and 2006 growing seasons to investigate the effect of inoculation with Azotobacter chroococcum (+ ,- ) and varying levels of nitrogen fertilizer Urea 46% N (0, 100, 200 kg/hectar) on quality yield of potato plant Solanum tuberosum L. cv. Desiree , a factorial randomized complete design (F-RCBD) was selected for the experiment with three replicates . The results showed that there was significant increase in the quality characteristic of yield (number of tuber /plant , weight of tuber (gm.), total yield /plant (gm.), and the productivity of unit area ), and the percentage of dry matter in tubers , and the percentage of mineral nutration in tuber (N, P, K, Ca) and the percentage of protein. As a result of treating inoculation with Azotobacter bacteria , and for the treatment of adding nitrogen fertilizer especially the level 200 kg/hectar and for the two growing seasons 2005 and 2006 . The result of interaction treatment between the inoculation with Azotobacter bacteria and the nitrogen fertilizer 200 kg/hectar showed that there was significant increasing in the tuber number/plant , weight of tuber (gm.), yield /plant (gm.), and productivity of unit area (t/hectar) ,where the results were (7.45 , 100.67 gm./tuber , 749.99 gm/plant , 29.32 T./hac. respectively for the first growing seasone, and (12.19 , 68.30 gm/tuber , 954.48 gm/plant , 37.32 T./hectar) For the seconed seasone. Also the interaction treatments between inoculation with Azotobacter and adding 200 kg/hectar urea lead to a significant increasing in dry matter and percentage of(N, P, K, Ca) and protein in tuber for the two growing seasons of 2005 and 2006.