STERILE FUNGI FROM ZOYSIAGRASS RHIZOSPHERE AS PLANT-GROWTH PROMOTERS IN SPRING WHEAT

Eleven out of 18 sterile fungal isolates and an isolate each of Penicillium sp. and Trichoderma sp. from the zoysiagrass rhizosphere were effective in enhancing the growth of two wheat varieties in greenhouse conditions. They enhanced the top length and top dry biomass of plants significantly and induced the plants to produce long earheads and more seeds. Notable among isolates were GS6-1, GS6-2, GS7-3, GS7-4, GS8-6, GS10-1, GS10-2, and GU23-3, which enhanced the growth by several times, resulting in a conspicuous growth promotion effect that differed depending on the variety. Penicillium and Trichoderma species were less effective than sterile isolates in enhancing growth. Seven of the 11 effective sterile isolates from the zoysiagrass rhizosphere (as determined under greenhouse conditions) and a wheat rhizosphere isolate (K-17) were further tested under field conditions. Most of the isolates except K-17 enhanced the growth of one variety, whereas a few isolates enhanced the growth of the other variety. However, at least four isolates each increased yields of both varieties. Isolate GS6-1, which was very effective under greenhouse conditions in promoting overall growth, was less effective under field conditions; however, the yield components were not affected. The efficiency of the plant growth promoting isolates depended upon the wheat variety and soil nutrient conditions in addition to their inherent growth promotion abilities.