Effect of Biofertilizers on Controlling Fusarium Solani f. Sp. Phaseoli

Abstract

A pot experiment was conducted to study the effect of seed and soil inoculation with a mixture of VAM-spores and/or mixture of Azotobacter chrococcum and Azospirilium lipoferum on controlling Fusarium Solani f. sp. phaseoli. Golmus was the most VAM-genus while Sclerocysts and Gigaspora were obtained in low frequency.

Number of VAM-spores increased with time and reached maxima at fruiting stage. Disease severity of root-rot was decreased when seed and soil were treated with tested biofertilizers. Root infection with VAM-fungi increased by ageing. Rotted roots of soybean plants (unnodulated) showed less infection with native VAM-fungi.

Resistance of soybean roots treated with biofertilizers against F. solani f. sp. phaseoli was histologically studied. Many lysed dark cells appeared in the epidermal and outer cortical cells due to root-rot disease. This produced an irregular dark epidermal layer. Less changes were showed when seeds and soil were treated with biofertilizers. Thickening of the cell walls through lignification and higher number of xylem vessels decreased the penetration and growth of the pathogenic fungus.