Studies On Testing Of Several Annual Flower Seed-Borne Fungi And Selection Of Seed-Coating Fungicide

Seed samples of two varieties of Salviax three varieties of Marigold and four varieties of Petunia totally nine varieties were collected and analyzed for seed-borne fungi by means of perti-dish testing. The isolates were purified and identified. The results showed that pathogens were detected in all the cultivars. The percentage of seed-borne fungi was 54.0% to 72.5% in Salvia; While the percentage varied from 11.5% to 13.0% in Marigold and 17.0% to 50.5% in Petunia. Accroding to the morphology, the isolates were confirmed as Alternaria(including A.alternata, A.tenuissima, A.infectoria), which was the dominant species in the experimental cultivars, Chaetomium, Penicillium and other four species(B, C, G,H) which had not been identified.Inoculated seeds with the fungi isolated from their own seed samples, then plant these seeds on the disinfected soil. The impact of the isolated fungi on seedling emergence was assessed. The result showed that isolations A (Alternaria alternata), E (Alternaria infectoria), G and I (Chaetomium sp.) had bad impact on seedling emergence.Two varieties each from Salvia and Marigold were treated with Thiram 50%WP, mancozeb 70%WP, Apron 35% SD, Carbendazim 50%WP, Prochloraz 25%EC, Hymexazol 70%WP , then plant these seeds on PDA plate and in soil. The result indicated that the disinfecting effect of Thiram 50%WP, mancozeb 70%WP and Prochloraz 25%EC were better than other fungicides, and their negative impact on seedling emergence were not showed .At the same time, the inhibiting effect of Thiram, Carbendazim, Hymexazol, Metalaxy, Carboxin, mancozeb, Prochloraz and Rizolex to A (Alternaria alternata), E (Alternaria infectoria), G and I (Chaetomium sp.) were determined. The result showed that inhibiting effect of Prochloraz was the best of all to 4 pathogens, EC50 were 0.78ug/mK 0.24ug/ml, 0.32 ug/ml和 0.07 ug/ml respectively; Rizolex was the second, EC50 for 4 fungi were 1.88 u g/ml,2.11 ug/ml,1.39 ug/ml 和0.86 ug/ml respectively. Also the association virulence of Prochloraz and Rizolex to 4 fungi were tested. The result showed that the proportion of 8 to 2 had the best inhibition effect to 4 fungi with EC50 were 0.66 u g/ml, 0.34 ug/ml, 0.24 ug/ml and 0.08 ug/ml respectively.Additionally, four flower seed coating were used to coat two varieties each from Salvia and Marigold seeds in the proportion of 1 to 30.The disinfection effect, germination percentage and germinating viability were measured in laboratory and growth vigor were estimated in field. Results showed that seed coating was safe to experimental seeds and could increase emergence rate, and improve the growth of seedling.