Chitosan and salicylic acid induced defense response against floral malformation in mango (Mangifera indica L)
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Date
2021-02
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Malformation is an ambiguous malady of mango (Mangifera indica L.) with tremendous economic importance through the mango growing regions. Present investigation was carried out at Horticuture Research Station, Patharchatta and Department of plant Physiology, College of Basic Sciences & Humanities, GBPUA&T, Pantnagar during the year 2019 and 2020. The experiment was laid out in Randomized Block Design (RBD) with three replications. Seven different concentrations of chitosan and salicylic acid ( Control, 0.25% CT, 0.50% CT 0.75% CT, 0.20% SA, 0.40%SA and 0.60%SA) were sprayed at three different stages I.e. prior to panicle emergence, pre bloom and full bloom in the month of February to March on two mango cultivars Amrapali (moderately susceptible) and Dashehari ( Moderately resistant). The effect of chitosan and salicylic acid treatment was evaluated with respect to morphological and physio-biochemical parameters. It was observed that chitosan and salicylic acid treatment significantly reduced occurrence of floral malformation as compared to control. Amongst varieties, Amrapali has significantly higher percent malformation than Dashehari. Length of healthy and malformed panicles, leaf area and physiobiochemical characteristics viz. chlorophyll fluoresencem MSI, chlorophyll a, b, total chlorophyll, total phenol , total flavonoid and total protein content, phenylalanine ammonium lyase, chitinase and 1, 3 glucanase activity significantly increased under 0.50% chitosan treatment while, fresh weight of malformed panicle decreased with respect to control. Therefore, chitosan 0.50% was found best for most morphological and physio-biochemial parameters. Highest macro and micro nutrients such as nitrogen, phosphorus and potassium, iron, zinc, copper and manganese content was recurded under 0.75% chitosan treatment. Salicylic acid treatment (0.40%) shows significantly increased proline content, superoxide dismutase, ascorbate peroxidase, catalase and glutathione reductase activity in dose dependent manner while hydrogen peroxidase activity was decreased. Overall findings of the present investigation suggested that pre- treatment of chitosan or salicylic acid at both 0.50% chitosan and 0.40% salicylic acid could help in maintaining vital physio-biochemical processes and induced defence response by eliminating the active oxygen species and strengthening plant defence mechanism. Chitinase and 1, 3 glucanase is an important and reliable screening markers which should be utilized for developing malformation resistant or less susceptible mango cultivars. This study will help the researcher to uncover the critical areas of chitosan on mango characteristics and malformation resistance. Therefore, in future chitosan can be used to induce the resistance against mango malformation.