GROWTH PROMOTION OF MAIZE BY LEGUME SOILS

Maize (Zea mays cv W64A × W182E) was grown in a low nutrient sandy loam. Inoculation with legume soils (4.1% v/v) gave a 3 to 4 fold increase in shoot growth relative to the control after 5 to 8 weeks growth in greenhouse conditions. Plants were routinely irrigated with 1/10 Hoagland solution (with 10m M KNO 3). With half strength Hoagland solution (10m M KNO 3) there was no clear growth response. This growth response was observed with a variety of legume soils but not with any of the maize soils tested. The response to alfalfa soil was eliminated or much reduced by gamma irradiation (3.6 Mrad) or autoclaving of the inoculum. The bactericide streptomycin had no effect on the growth response whereas the fungicides benomyl and PCNB eliminated it. This suggests that fungi and not bacteria are involved in the growth promotion. © 1990 Kluwer Academic Publishers.