STUDIE5 ON NITROGEN FIXERS AS PLANT GROWTH PROMOTING RHIZOBACTERIA IN LEGUMES AND NON-LEGUMES

Abstract

Two pot experiments were carried out to study the effect of nitrogen fixers as plant growth promoting rhizobacteria on cowpea and potato grown m sandy soil at Ismailia Experimental Research Station in Ismailia Governorate, ARC. The most important results for cowpea experiment was summarized that, co-inoculation with Serratia plus 15 Kg N/fed gave the best results for number and dry weight of nodule whereas, mixed inoculant plus compost gave the san1e responded especially under Serratia treatment + 15 kg N/fed while mixed inoculant +15 Kg N/fed recorded the best results for plant height, shoot dry weight and leaf area. Whereas, in the presence of compost B. polymyxa had a significant effect on all plant growth aspects. Chlorophyll content significantly increased as responded to rhizobacteria in the presence <Jr absence of compost. The best results recorded by mixed inocula plus compost. The nutrient N, P in ;:lar.l tissues was increased and the best results of shoot nitrogen obtained by B. polymyxa while the root nitrogen attained by mixed inoculant. Also, the contents ofN and P of shoot and root were more enhanced in case of compost addition, particularly, with co-inoculation with dual inoculants (Serratia+Bacillus). In addition, crude protein of seeds increased due to mixed inoculants+l5 KgN/fed or B. polymyxa in the presence of compost. Also, B. polymyxa increased crude protein of straw in the presence or absence of compost. Soil soluble nitrogen increased due to mixed inoculant plus compost while available- P and DHA increased due to mixed inoculant in the presence or absence of compost. Regarding potato experiments, results displayed that most plant parameters gave significant response to treatments under investigation. The effects of rhizobacteria on plant growth aspects were significantly increased especially in the presence of B. polymyxa. Total chlorophyll content increased significantly by B. polymyxa treatment as a superior treatment. Azospirillum treatment recorded the best results as for shoot content of nitrogen. But the best results of root nitrogen content obtained by B. polymyxa. The highest values of root and shoot phosphorus were attained by B. polymyxa. This significant effect of all treatments on the yield of potato and best results recorded by Rhizobium. Also, increasing ofN- fertilizer level applied tended to gradually increase the number and fresh weight of potato tubers. Total protein percentage increased due to PGPR especially by Rhizobium treatment plus 90 Kg N/fed. Ascorbic acid content significantly responded to PGPR especially with B. polymyxa. On the other hand, total phenols decreased by PGPR inoculation. There was no significant effect on soluble carbohydrate while total and non-soluble carbohydrate increased especially by B. polymyxa. The obtained data concern amino acid showed fluctuated change in differences among all anlino acid percentage between the treatments under investigation. Soluble- N, available-P and DHA were pronounced responded to PGPR and N-fertilization, particularly with B. polymyxa.