Evaluating the efficacy of chitosan and salicylic acid on photosynthetic pigments and antioxidant enzymes towards resistance of mango malformation

Abstract

The mango malformation is an ambiguous malady of mango (Mangifera indica L.) with tremendous economic importance throughout the mango growing regions. The effect of different concentrations of chitosan and salicylic acid on photosynthetic pigments and antioxidant enzyme responses towards the resistance of mango malformation was investigated. The experiment was carried out in on seven-year-old trees of two different mango cultivars Amrapali (moderately susceptible to mango malformation) and Dashehari (moderately resistant to mango malformation) with seven treatments and three replications during February and March 2019-2020. The foliar application of chitosan and salicylic acid was done at three different stages i.e. prior to panicle emergence, pre blooming and full bloom. The pooled data over the years 2019 and 2020 revealed that the highest chlorophyll fluorescence and photosynthetic pigments in Dashehari as compared to Amrapali. However, Amrapali was recorded maximum malformation (%). Chitosan (0.50%) shows the maximum increase in chlorophyll fluorescence, leaf area, photosynthetic pigments, proline and total phenol contents in both the varieties over control. On the contrary, antioxidant enzymes such as superoxide dismutase, ascorbate peroxidase and guaiacol peroxidase were reported higher in both the varieties at 0.40% salicylic acid which, was statistically at par with 0.50% chitosan treatment. However, the catalase activity decreases at lower concentration and increases at high concentration of chitosan and salicylic acid. Therefore, it was concluded that protective application of either chitosan or salicylic acid prior to panicle emergence, pre blooming and full bloom reduced the negative effect of mango malformation and elevated the defense induced antioxidant activities to confer resistance to floral malformation.