VESICULAR-ARBUSCULAR MYCORRHIZAE-MEDIATED UPTAKE AND TRANSLOCATION OFP AND ZN BY WHEAT IN A CALCAREOUS SOIL

Vesicular-arbuscular mycorrhizae (VAM) have been credited with improvi ng the growth and mineral nutrition of many host plants but these effe cts are moderated by soil factors and nutrient balance. We investigate d the combined effects of VAM, zinc and phosphorus application on the growth, uptake and translocation of nutrients in wheat using a calcare ous soil marginal in P and Zn. Wheat was grown in a growth chamber und er various combinations of VAM, P and Zn with measurements done at hea ding stage and maturity. Vegetative dry matter accumulation was increa sed by P additions and reduced by VAM infection. Both P addition and V AM infection increased grain yield. Zinc concentration and uptake were generally reduced by P additions and VAM infection. There was an abse nce of antagonistic effects of Zn additions on P concentration and upt ake. In contrast, VAM infection had both positive and negative effects on P uptake depending on the growth stage and translocation of nutrie nts. We observed that in calcareous soils where the Zn and P fertilize r combinations were adequate for growth, the role of VAM in enhancing the translocation of Zn and P from root and straw to grain is benefici al towards seed set and yield.