Plant extract effect on seed-borne pathogenic fungi from seeds of paddy grown in Southern India

A total of 40 seed samples of different cultivars of paddy, collected from southern part of India, were mycologicaly analyzed by agar plating method on Czapek's-Dox-Agar (CzA) medium and Standard Blotter Method (SBM), revealed the occurrence of 33 diverse fungal species belonging to 16 genera. The species of Drechslera oryzae (RP 82.5) was recorded with the incidence and relative preponderance (RP), followed by Curvularia lunata (RP 67.5) and Aspergillus niger (RP 65.0) respectively. The data on the diversity and incidence of fungal species would be a great importance in the region for predicting the extent of pre-and post-infections.In vitro antifungal activity assay of methanol extract of 12 plants belonging to different families were tested against eight pathogenic fungal species viz., Alternaria alternata, Aspergillus flavus, Curvularia lunata, Drechslera oryzae, D. halodes, Fusarium moniliforme, Pyricularia oryzae and Trichoconis padwickii by poisoned food technique. The results revealed that, methanol extract of Acacia nilotica, Caesalpinia coriaria, Decalepis hamiltonii, Emblica officinalis, Lawsonia inermis and Mimosops elengi showed significant antifungal activity at 3500 μg/ml concentration. Comparative evaluation of the extracts with the synthetic fungicides viz., bavistin, blitox, captan, dithane M-45 and thiram at the recommended dosage revealed that, antifungal activity of methanol extract of D. hamiltonii, L. inermis and M. elengi was almost equivalent. These plants can possibly be exploited in the management of seed-borne pathogenic fungi and prevention of biodeterioration of paddy in an eco-friendly way