Effect of Glomus etunicatum on soybean (Glycine max Merr.) growth, nitrogen and phosphorus nutrition and soybean nodule activities under different phosphorus application levels in an andosol subsoil
1998
Satoh, T. (Tokyo Univ. of Agriculture and Technology, Fuchu (Japan). Faculty of Agriculture) | Kume, T. | Hirata, H.
The responses of soybean (cv. T202) to Vesicular-Aubuscular Mycorrhizal Fungus (VAMF; Glomus etunicatum) under 3 different phosphorus application levels (P1, 100mg P; P5, 500 mg P; P30, 3000 mg P/2 x 10(-4) a pot, 2.3 kg air dry soil) in an Andosol subsoil (Bray II-P 0.1 mu-g g(-1)ds.) were examined in regards to growth, VAM formation, acetylene reduction activity (ARA), N accumulation and P absorption at the growth stages of initial flowering, milk-ripening and maturing. Positive effects of VAMF infection on growth, P and N accumulation, and ARA were obtained,especially in the earlier growth stage, corresponding to the level of VAMF infection rates and infected root lengths which were higher in lower P applications (P1 and P5). In the initial flowering stage, significant stimulations of ARA and P accumulation in nodules were observed due to VAMF infection at lower P application levels (P1, P5), resulting in earlier N accumulation in pod-grain at the milk-ripening stage, however, accompanying steep decreases in ARA and nodule P concentrations at this stage as compared to non-VAMF treatment. Even under the 50% cut-off of light by shading from just before milk-ripening to the maturing stage, positive effects of VAMF on growth and N and P accumulation were found. Under the high-P application level (P30), VAMF infection affected soybean growth negatively in the milk-ripening stage, whereas in the final maturing stage, it brought about stimulative effects on dry matter production and N and P accumulations in pod-grain through maintaining ARA activity, maybe due to unknown factors except the improvement of P nutrition
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