Effect of phosphorus and nitrogen fertilizers, irrigation systems and mycorrhizal infection on soybean nodulation

الملخص EN

Two experiments were carried out in the experimental farm at Shalakan in the Kulubia Governorate in Egypt in the summer of both 1996 and 1997 to study the effect of nitrogen and phosphorus fertilizers, irrigation systems, and mycorrhizal effect on nodulation and mycorrhizal spores production on soybean.

Soybean (Glycine max (L) Merr) Giza 21 cultivar was planted using three irrigation systems drip, furrow and sprinkler convention with two levels of nitrogen fertilizer ( 0 N and 35.7 kg N ha-1) with two forms of phosphorus super phosphate containing 15.5% P2O5 and rock phosphate containing 26% P2O5 and with two mycorrhizal infection (VAM treatment and without VAM).The number and dry weight of nodules were significantly influenced by drip > furrow< sprinkler irrigation at stage of full bloom (R2) and beginning of seeds (R5) stages.

The highest amount of nitrogen fertilizers, (35.7 kg N ha-1 significantly increased the number of nodules plant-1 compared to the control treatment.

The interaction effect between irrigation and nitrogen fertilizer at R2 and R5 for the number of nodules plant-1 and at R5 for the dry weight were mainly as those of adding nitrogen fertilizer at a rate of 35.7 kg N ha-1 under furrow irrigation.

The number and dry weight of nodules plant-1 were significantly increased by infestation of fungus vesicular carbuncular mycorrhizea, VAM.

Infestation of soil by VAM significantly influenced the number of mycorrhizal spores in the rhizosphere of soybean plants grown under different irrigation systems.

Percent maximum root infection occurred under drip irrigation followed by sprinkler irrigation and the minimum infection under furrow irrigation.