Biochemical basis of resistance to leafminer in castor (Ricinus communis L.)

The present study was conducted to establish relation between total phenol concentration and resistance against leafminer, Liriomyza trifolii (Burgess), Diptera Agromyzidae, which causes severe damage to castor (Ricinus communis L.) foliage. Crosses were made between leafminer resistant dark purple (RG 1930) and susceptible green leaf (RG 2788) parents and vice-versa. Parents and F1, F2 and F3 generations were screened against leafminer. Total phenol concentrations in them were estimated. High positive significant correlation was observed between leafminer resistance and total phenol concentration. Dark purple leaf progenies possessed high concentrations of total phenol and were resistant to leafminer whereas green leaf type progenies had low total phenol concentrations and were susceptible. The study clearly established the significant relation between high total phenol concentrations and leafminer resistance in castor and projected that selecting dark purple leaf phenotype in breeding programmes is an effective visual and reliable approach for indirect selection of leafminer resistance.