Responses of Three Crop Species to Vesicular‐arbuscular Mycorrhizal Infection on Zinc‐ Deficient Indian Soils

S ummary Maize, wheat and potato plants were grown on three very zinc‐deficient Indian soils in a pot culture study; the treatments were inoculation of seed with the spores of the vesicular‐arbuscular (VA) mycorrhizal organism, Glomus macrocarpus , dressing with 65 ZnSO 4 to supply 10 p.p.m. Zn, or both with appropriate controls. Plants raised from inoculated seed usually exhibited root infection and were observed to assimilate significantly more Zn from the soil, than non‐mycorrhizal plants. For maize grown on Daurala soil, Zn application appeared to stimulate endomycorrhizal efficiency in collecting Zn for the host plant; for other crops and on other soils, fertilizer‐Zn did not improve plant uptake of Zn, and so it was concluded that mycorrhizal infection, by itself, could take care of the total Zn requirement of the higher symbiont. Yield responses closely followed the pattern of Zn uptake, with the exception that tuber production in the potato was unaffected by any of the treatments on all the soils. The starch contents of the tubers was, however, found to increase commensurately with the level of Zn in leaves. It is concluded that the observed mycorrhizal effect restricts itself to the more easily available fractions of Zn in deficient soils. The value of artificial inoculation with VA‐mycorrhizae under field conditions to upgrade nutrient‐deficient soils is discussed in the light of the above findings.