Effect of cell free culture filtrates (CCF) of two strains of Rhizoctonia bataticola (Taub) butler on seed germination and seedling growth of mulberry ( Morus alba L.).

摘要

Seed germination and seedling growth are influenced by the toxic metabolites produced by pathogenic fungi. Mulberry root rot caused by Rhizoctonia bataticola is one of the major soil borne disease leading to the death of the plants with in a short period of infestation. Two strains R2 and R3 isolated from root rot infested mulberry roots, pure cultures were maintained on PDA slants for further study. CCF at 5, 10, 25, 50, 75 and 100 per cent concentrations were tested on seed germination and seedling growth on 7th and 21st day respectively. Culture filtrates of both strains inhibited the seed germination, shoot and root elongation at all concentrations. At 100% CCF both strains completely inhibited the seed germination. At 75% CCF R3 strain inhibited the germination up to 89.65% over control and R2 was totally inhibited. At 50% CCF 93% and 82.75% inhibition was observed in R2 and R3 stains respectively. The minimum inhibition of seed germination was observed at 5% CCF of both strains. Similarly, the shoot and root elongation was inhibited by both strains at all concentrations of CCF and the inhibitory effect was more on root length than shoot. The percent seed germination and shoot and root growth was inversely proportional to the increase of CCF percentage. The present investigation revealed that the CCF of both the strains of Rhizoctonia bataticola which inhibited the mulberry seed germination and seedling growth, may be due to the release of metabolites polygalacturonate, trans-eliminase and pectin methylesterase in to the CCF.