BIOLOGICAL STUDIES ON SEED BORNE MYCOFLORA OF EXOTIC TOMATO SEED

Abstract

Sustainable vegetable farming is under stress due to the presence of biotic and a-biotic factors. Most of the diseases/stress caused by fungi that survive mostly in seed. The current study is carried out to evaluate the presence of fungi on exotic seeds of tomato. This research work included the isolation and identification of seed-borne mycoflora on ten cultivars tomato. It was found that some variety was highly resistant, and some cultivars show was highly susceptible amongst the ten cultivars. Pathogenicity of four highly aggressive seed-borne fungi viz Alternaria alternate, Rhizoctonia solani and Fusarium oxysporum were assessed through lab based in-vitro and in vivo techniques. All the germinated seeds were infected by these fungi with varying degree of variability or aggressiveness Disease index varied from 0.29 to 0.91 for all tested materials. All pathogenic fungi on each cultivar significantly reduced germination and produced more abnormal seedlings compared to control. The most common four seed-borne fungi (Aspergillus niger, Alternaria alternata, F. moniliforme, and F. oxysporum) were selected to study their transmission from seeds to seedlings. Results revealed that pathogenic fungi move from seed to seedling and other part of plant but saprophytic fungi were can not able to move in plant parts systemically. While the means value showed that the highest transmission was during germination stage followed by seedling stage on leaves and on stem. The outcome of this study will help to regulate the import of unhealthy vegetable seeds and also help in quarantine pathogens associated with imported seed, that prevent agricultural and natural resource from risk associated with the entry of seed borne pathogens in the country.