Field and growth chamber evaluation of components of partial resistance to Colletotrichum truncatum in lentil

The components of partial resistance to anthracnose (Colletotrichum truncatum) were evaluated in lentil (Lens culinaris) in a growth chamber and in the field. Lines PI 299331, PI 320937, PI 345629, 458-57, and cv. Indianhead, with different levels of partial resistance and the susceptible cultivar Eston were inoculated in a growth chamber and in the field using a single virulent isolate of C. truncatum. Incubation and latent periods as well as sporulating lesions were measured on stems. A computer imaging system was used to measure lesion number, lesion size, and percent necrotic area per square centimetre on stem samples. Area under the disease progress curve (AUDPC) values were also calculated using disease severity from the field samples. Lines PI 320937, PI 345629, 458-57, and cv. Indianhead were found to have high levels of partial resistance, as indicated by significantly smaller and fewer lesions and longer incubation and latent periods than cv. Eston. For each component, PI 299331 was intermediate except for lesion size, which was larger than that of cv. Eston. The data for all the components obtained in the growth chamber were significantly correlated with those measured in the field (r = 0.86-99, p less than or equal to 0.01) and with disease severity and AUDPC. Therefore, evaluation of partial resistance to anthracnose in lentil can be conducted under controlled conditions and in the field.