Effect of spore concentration on germination and autotropism in Trichoderma hamatum

Abstract

The effect of spore concentration on spore germination and germtube growth of Trichoderma hamatum on water agar and on potato dextrose agar (PDA) was studied. Increasing inoculum size up to 109 spores/plate on PDA and up to 107 spores/plate on water agar shortened the incubation period required for germtubes emergence and increased germination rate. However, on water agar germination was inhibited at 108 and was completely arrested at 109 spores/plate. Inhibition in germination of 107 spores/plate was observed on water agar when the plates were preincubated with 109 spores/plate for 5 h or more. Addition of glucose and ammonium nitrate to the water agar medium allowed only 25% of the spores to germinate at 109 as compared to 78% at 107 spores/plate after 8 h of incubation. Addition of polysaccharides to the C + N supplemented medium, significantly increased germination up to 84% as compared to 100% on PDA, after 8 h of incubation. Germlings of Trichoderma hamatum phialospores exhibited positive autotropism and anastamosis on both media. The phenomenon was positively related to inoculum size, being most pronounced at 107 spores/plate.