Effectiveness evaluation of VAM fungi on enhancement of growth and phosphorus uptake of corn and soybean

Effecfs of vesicular-arbuscular mycorrhiza and rock phosphate were determined with sweet corn and vegetable soybean in kamphaengsaen soil. Three species of VAM (Acaulospora scrobiculata, Acaulospora dilatata, Entrophospora sp. for corn and Entrophospora sp., Glomus tenuis, Glomus claroideum for soybean) and uninoculated treatment (control) including with four levels of rock phosphate (0,25,50 and 100 kg/rai) were examined. The maximum yield of corn (556.00 kg/rai) was achieved from Acaulospora dilatata+50 kg/rai of rock phosphate treatment. The second was 535.00 kg/rai which inoculated with Acaulospora scrobiculata. Acaulospora scrobiculata infected corn root very fast and the maximum percentage of root infection by this species at 6 weeks was 79.17 percent, then, increased to 88.67 percent at harvest. The maximum dry weight of above ground stem, 715.66 kg/rai, was found in Acaulospora scrobiculata+50 kg/rai of rock phosphate treatment. The maximum nitrogen and phosphorus percentage of 6 week-plant applied with Acaulospora dilatata+50 kg/rai of rock phosphate were received, but nitrogen percentage of plant in the same treatment was declined to 2.72 percent at harvest. Meanwhile, maximum phosphorus percentage in plant (0.38 percent) was found in Entrophospora sp.+25 kg/rai of rock phosphate treatment. In soybean, although the yields of almost plants were rather low, VAM inoculation and rock phosphate application raised the certain amout of plant yield. Yield of plant applied with Glomus claroideum+50 kg/rai of rock phosphate was maximized as much as 294.33 kg/rai. Entrophospora sp. stimulated not only quantity but also the rate of soybean root infection. Maximum dry weight of 6 week-plant (7.9 g/plant) was found in Entrophospora sp.+100 kg/rai of rock phosphate treatment. Application of rock phosphate affected the nitrogen increasing percentage of soybean at 6 weeks, but its' effect was reduced at harvest period. Phosphorus percentage of plant at harvest period was affected by application of rock phosphate. Sole inoculation of Entrophospora sp. enhanced increasing of phosphorus (0.35 percent). The quantity of available phosphorus in soybean-cultivated soil which inoculated with Glomus tenuis and Glomus claroideum had a distinct trend to be greater than that of uninoculated soil.