PITIPONG THOBUNLUEPOP1, CHAIWAT JATISATIENR2, ARAYA JATISATIENR2, ELKE PAWELZIK1, SUCHADA VEARASILP3
1Georg-August-Universität Göttingen, Department of Crop Science, Quality of Plant Products, Germany
2Chiang Mai University, Department of Biology, Thailand
3Chiang Mai University, Department of Agronomy, Thailand
Presently, chemical seed treatments are in discussion due to their possible directly or indirectly impacts on human health or other living organisms. They may also negatively affect the ecosystem and the food chain. In rice seeds, chemicals may cause phytotoxic effects including grain degradation. Eugenol is the main component of clove (Eugenia caryophillis) oil and it is known as an active agent against many pathogenic seed borne fungi. It acts simultaneously as bactericide, fungicide and virocide. Moreover, it is non-toxic for humans if it is applied in normal doses. The present study compared the inhibitory effect of the following applications for rice seed treatment to protect them against seed borne fungi during 12 months of storage: eugenol incorporated into chitosan"=lignosulphonate polymer, only chitosan"=lignosulphonate polymer and captan. The Blotter method was used for the determination of seed infection. The obtained results of fungi inhibition showed at first that captan treatment led to a better, i.e. longer, inhibitory effect on Alternaria padwickii, Rhizoctonia solani, Curvularia sp., Aspergillus flavus, and Aspergillus niger than eugenol incorporated into chitosan"=lignosulphonate polymer. Secondly, eugenol incorporated into chitosan-lignosulphonate polymer showed the longest inhibitory effect against Bipolaris oryzae and Nigrospora oryzae compared to captan and only chitosan"=lignosulphonate polymer treatments. Finally, both captan and eugenol incorporated into chitosan"=lignosulphonate polymer showed non"=significant different inhibitory effect on Fusarium moniliforme. The variant of only chitosan"=lignosulphonate polymer for seed coating was only during the first 6 months of storage able to inhibit all species of the observed seed borne fungi, whereas captan and eugenol incorporated into chitosan"=lignosulphonate polymer were capable to inhibit most of the fungi until 9 months of storage.
Keywords: Antifungal activity, eugenol, rice seed borne fungi, seed coating technology