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Abstract
Leaf blight caused by the fungus Phytophthora colocasiae Racib. (1900) causes great damage to many areas of intensive taro cultivation. Our research was conducted to evaluate the fire blight resistance of accessions in the conserved taro group, thereby screening and detecting leaf blight resistance accessions. These accessions will be put into long-term conservation and serve the program of breeding taro varieties resistant to leaf blight. In this study, 209 accessions from Northern taro collection were evaluated for resistance by in vitro infection of detacted leaf disc with the fungus P. colocasiae based on the leaf area showing disease symptoms. Among them, 4 accessions with immunity were detected, including SP-19-027 collected in Dien Bien province, Phuoc Thao taro (28351) in Cao Bang province, Ma pho taro (11613) in Lai Chau province and Hau danh taro (11545) in Tuyen Quang province with immunity; 12 accessions for resistance; 62 accessions for moderate resistance; 58 accessions for susceptibility and 73 accessions for high susceptibility to P. colocasiae strain. Testing fungal resistance of the taro accessions (including 4 immune and 12 resistant taro accessions) after 7 days of in vivo infection showed results consistent with those assessed by in vitro infection. However, under fungal infection pressure lasting up to 15 days, the resistance level of some taro accessions decreased. The research results have provided data on resistance to the fungus causing leaf blight, contributing to building a database of taro accessions in our country. The highly resistant accessions discovered in the study have implications for breeding programs of taro with resistance to P. colocasiae fungus.