Impact of Bio-fertilizers and Organic Phosphorus on Biological Nitrogen Fixation by Cereal Crops Using Nuclear Techniques

Abstract

Phosphorus addition stimulates the process of biological nitrogen fixation. Maize (Zea mays L.) and pearl millet (Panicum miliaceum L.) crops may efficiently fix atmospheric N if an adequate amount of P is present in the soil. Because of the deficiency of phosphorus supply and availability remains a severe limitation on nitrogen fixation .So fungal species can be isolated and study it's ability on organic matter (OM) degradation and phosphorus availability from organic sources to improve biological nitrogen fixation (BNF) process and the contribution of fungi and OM on growth parameters of maize and pearl millet crops . For these purposes twelve fungal strains were isolated from different parts in Egypt. From these isolates, only four fungal strains were chosen depending on their capacity to convert sparingly soluble P (tri-calcium–P ) to soluble one , clearing a halo zone on petri dish (A.niger, A.flavus, A. Ficuum and F.oxysporum) produced halo zone around the colonies. A.niger was the most efficient phosphate solubilizer on Pikovskaya's agar plates (PVK) where solubilization index (PSI) as indicator for soluble P , 2.4 followed by A. flavus with PSI = 2.3. Because of A.niger and A.flavus showed maximum phosphate solubilization index (PSI) they were selected for further studies as qualitative and quantitative activities. The estimated soluble -P was recorded for A.niger (73.8 μg/ml), A.flavus (72.6 μg/ml) and study the effect of environm