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Abstract

A pot experiment was carried out with a sterilized soil to compare the enhancement of growth due to arbuscular mycorrhizal (AM) fungal inoculation in maize cultivars that differ in downy mildew resistance (DMR) and in their fertilizer requirements to attain maximum yields. A 4 x 3 factorial in complete randomized block design with 3 replications was employed. The first factor comprised two open-pollinated maize cultivars and two maize hybrids. The former two were Suwan-1 selection cycle 0 (SW1C0), a non-DMR cultivar and Suwan-1 selection cycle 11 (SW1C11), a cultivar with high yield at high soil fertility and DMR. The latter two were Suwan 2301 (SW2301), a cultivar requiring low rates of N and P fertilizers, and Suwan 3851 (SW3851), a cultivar requiring high rates of N and P fertilizers, both of which were downy mildew resistant. The second factor comprised three AM fungal inoculation practices, namely, non-inoculated with AM fungi, inoculated with Scutellospora fulgida and inoculated with Glomus aggregatum. The DMR and non-DMR maize cultivars gave comparable responses to AM fungi. The cultivar requiring high rate of fertilizers was lower in its response to AM fungi in P and K uptake than the cultivar requiring low rate of fertilizers. The lower response in P uptake was explained by higher P utilization efficiency of the cultivar whereas the lower response in K uptake was not related to K utilization efficiency of the cultivar. The maize cultivars lower in nutrient (N, P and K) efficiencies or in shoot dry weight gave greater responses to AM fungi in shoot dry weight.