Diverse Response of Promising Taro (Colocasia esculenta var antiquorum) Cultivars to Phytophthora Blight
The leaf blight of taro caused by Phytophthora colocasiae is the most serious disease which causes significant damage to crop yield. With the aim of ascertaining the field resistance to Phytophthora leaf blight and in vitro response to leaf blight infection, nine taro cultivars were tested. Cultivars showed varying degrees of resistance to blight in field tests during 2002-2004. Muktakeshi, Jhankri, BCC-1, Topi and BCC- 21 were identified as slow blighting cultivars. The radial growth of lesions, lesion distribution on leaf and sporangia liberation from lesion in different cultivars were also investigated. The magnitude of sporangium production in susceptible cultivar, Telia was very high which could lead to secondary spread of the blight pathogen. In response to artificial infection of Phytophthora, a similar trend of field reaction was noticed in the test cultivars. The strong phenotypic evidence of the cultivars demonstrated a continuous range of variation in infection from high susceptibility to moderate resistance. The leaf and petiole characters, leaf thickness, angle of divergence of leaf to petiole were studied and categorized.