Evaluation of nitrogen-fixing commercial biofertilizers on some gramineous plants under desert conditions

Abstract

A pot experiment was carried out to cultivated two sorghum varieties namely sweet sorghum (Sorghum vulgare var. saccharatum) and Sudan grass (S. vulgare var. sudanese ) in sandy soil in the presence of organic manure (compost at a rate of 0.1%) and inoculation with 3 commercial N­ biofertilizers (cerealin, rhizobacterin a & b). Inoculated treatments were provided with half the normal field dose of inorganic N- fertilizer, while the full dose was used in uninoculated treatments. It was found that inoculation with rhizobacterin a (containing asymbiotic N2- fixers) gave the highest growth and Nr ase activity in the rhizosphere of the growing plants. · Trials were paid to develop p-nodules (fixing atmospheric nitrogen) on the roots of sorghum plants by the aid of flavonoids (8 compounds), 2,4-D or grain extracts and inoculation with symbiotic N2- fixers (R. leguminosarum, B. japonicum and A. caulinodans). Para -nodules were noticed on the roots of tested plants associated with high levels of N2-ase activity, especially in the case of inoculated plants treated with 2,4-D in a concentration of2 ppm.