COMPONENTS OF QUANTITATIVE RESISTANCE TO BLIGHT IN FOUR CASHEW CULTIVARS AND THEIR RELATIONS WITH FIELD ASSESSMENTS

Abstract

Occurrence of blight on the four cashew clones named AC4, AC10, AZA2 and AZA17 was investigated under in vitro and field conditions, and the resistances of different clones to the disease were analyzed. AC10 (2.27 x 107) had the highest number of spores per unit area followed by AC4 (1.61 x 107), AZA17 (7.25 x 106) and AZA2 (6.67 x 106) respectively. AZA2 recorded significantly higher latent period (26 h) followed by AZA17 (23 h), AC10 (22 h) and AC4 (20 h). AC10 had the highest lesion size 3 days after inoculation followed by AZA17, AC4 and AZA2 respectively. AC10, AC4 and AZA17 genotypes had the highest number of lesions increase per day (2) while AZA2 revealed a low increase of lesions per day. Lowest mean rate of infection (r) was observed in AC4 which ranged between 0.10 and 0.29 whereas AC10 recorded higher rate of infections which ranged between 0.45 and 0.48. It shows that cashew clones AZA2 and AZA17 are more tolerant to cashew blight pathogen.