The effects of the three soil-inhabiting fungi on peanuts grown under germ-free conditions

Abstract

Excised peanut embryos were sterilized by treatment with 1% NaOCl tor 5 minutes, and placed in 250-ml flasks containing nutrients and expanded granular shale. Nutrients consisted of Hoagland's solution supplemented with 1% sucrose and 0.03 ppm gibberellic acid. Plants were grown for 4 weeks in flasks placed between tubes of fluorescent lights at room temperature. When the plants were 2 to 3 inches tall the flasks were inoculated in the root zone singly and in all combinations with Aspergillus flavus, Streptomyces griseus, and Trichoderma sp. All 3 organisms invaded the root tissue. When compared with uninoculated check plants, S. griseus individually caused no measurable damage, but in combination caused stunting and chlorosis. A flavus and Trichoderma sp. alone killed plants within 15 and 20 days, respectively, after inoculation; while in combination they killed plants within 15 days. Inoculations of plants with all 3 fungi in combination caused less damage.