Studies on biochemical mechanism of resistance for the management of Marssonina leaf blotch of apple caused by Marssonina coronaria (Ellis & J. J. Davis) J. J. Davis

Abstract

To study the mechanism of resistance developed in three different cultivars of apple viz; Starking Delicious, Tydeman’s Early Worcester and Granny Smith against Marssonina coronaria , after treatment with SAR inducing chemicals salicylic acid (SA), dipotassium phosphate (K2HPO4) and acibenzolar-S-methyl (ASM) contents of total phenol, reducing sugar, non -reducing sugar and activities of polyphenol oxidase (PPO), and peroxidase (POD) were assayed at three sampling periods (48,72 and 96 hours). The results revealed that SA treated leaves of cultivar Granny Smith recorded highest amount of phenol (49,53.66,57.33 mg/g), reducing sugar (16,16.33,17.66 mg/g), non-reducing sugar (2.90,3.13,3.53 mg/g) content, peroxidase (30,29.33,36) and polyphenol (26,30,34) activity in all the sampling intervals followed ASM and K2HPO4 treated plants. When compared among the cultivars maximum production was observed highest in cultivar Granny Smith which was followed by cultivars Tydeman’s Early Worcester and Starking Delicious. The present study showed that application of systemic acquired resistance (SAR) chemical can induce resistance in apple plants against Marssonina blotch caused by M. coronaria showing strong correlation between the ability of elicitors to enhanced plant disease resistance and elicitation of defence related enzymes. Thus, using SAR chemicals to induce resistance to apple against Marssonina blotch caused by M. coronaria, may provide a practical supplement to an environmentally friendly disease management when it is combined with appropriate integrated disease management practices.