Impact of Aspergillus flavus on Rice Seedling Growth and Aflatoxin B_1 Production

摘要

Fungi are known to produce substances toxic to plants, which affect adversely the seed germination and seedling vigour. We investigated the effect of Aspergillus flavus inoculum on seedling growth and production of aflatoxin B_1. Germination was reduced in A. flavus treated seeds of cv. Krishna Hamsa, Mandya Vijaya, HR 12, Pusa Basmati 1, Vasumati, TNI, Swarnadhan and Rasi, from 22-2 per cent; it increased in Prasanna and Shanti. There was no influence of treatment on seeds of Vikramarya. The lengthof root and shoot reduced in Ajaya and TNI and increased in Samba Mashuri, Krishnahamsa, Mandya Vijaya, Pusa Basmati 1 and Vikramarya. In TLC plates, aflatoxin Bl was not detected in samples from root and shoot of seedlings treated with A. flavus. Therewas no infection or colonization of A. flavus on seedlings raised from seeds treated with inoculum. Aspergilli appear to pose a problem only at or after grain formation and during post harvest stages. However, in vitro aflatoxin B_1 was detected in cultures of A. flavus on paddy and milled rice grains of all cultivars. The aflatoxin production on paddy substrate was max. in HR 12 (608 mg/kg) and was at par (242-270 rag/kg) in Samba Mashuri and Ajaya; it was low in the rest. A. flavus inoculated on milled rice grains showed from a rain. of 4018mg/kg in cv. Swarnadhan to a max. of 4655 mg/kg cv. Ajaya.