EFFECT OF SALICYLIC ACID ON BIOCHEMICAL AND PHYSIOLOGICAL CHANGES IN PIGEON PEA (Cajanus cajan L.) IN RESPONSE TO SALINE WATER STRESS 2843
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Date
2019-06
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JAU, JUNAGADH
Abstract
Pigeon pea is one of the most important pulse crop growing in Gujarat. The problem of salinity stress due to saline water in Gujarat is prevailing from seed germination to harvest of the crop. The present work throw light on the effect of salicylic acid on physiological and biochemical changes in response to salinity stress to tolerate the stress effects and increase the production as well as productivity of pigeon pea under salinity stress. Susceptibility minimized by conferring resistance against the salinity stress condition through salicylic acid treatment. Pot experiment was conducted to investigate the effect of exogenous application of salicylic acid (SA) under saline water stress on physiological, biochemical parameters and enzymatic activities of pigeon pea (Cajanus cajan L.) leaves. The experiment was conducted in factorial completely randomized design with three salicylic acid concentrations [0.0 ppm (C1), 100 ppm (C2) and 200 ppm(C3)], three salinity levels [Normal water (S1), 4.0 dS/m (S2) and 8.0 dS/m(S3)]. The pots were irrigated with different concentrations of saline water and plants were sprayed with salicylic acid at 18 and 26 DAS (Days after Sowing), samples were collected at 28 DAS for the analysis. The observations were recorded for the parameters viz., relative water content, membrane stability index, chlorophyll content, total phenol content, true protein, free amino acids, total soluble sugars, reducing sugars, non reducing sugars, total carbohydrate, proline, polyphenol oxidase, peroxidase, and catalase.In the treatment S3 (saline water 8 dS/m), the physiological parameters like relative water content (RWC), membrane stability index (MSI), chlorophyll a, chlorophyll b and total chlorophyll of pigeon pea leaves reduced significantly due to saline water stress effect. Physiological parameters in leaf tissues of pigeon pea collected from saline water 8 dS/m (S3) treatment showed reduction in their mean values by 11.08 %, 55.06 %, 14.58 %, 38.67 % and 20.41 % in RWC, MSI, chlorophyll a, chlorophyll b and total chlorophyll, respectively compared to S1 (no saline water) treatment. The increase in the content of physiological parameters was more prominent with the increase of salicylic acid concentration from no salicylic acid to salicylic acid 200 ppm. In present study, it was observed that biochemical parameters like total phenol, free amino acids, total soluble sugars, reducing sugars, non reducing sugars, and proline in leaves were increased due to saline water stress, while true protein and total carbohydrate were declined. Leaf samples from treatment S3 showed rise in the biochemical parameters like total phenol, free amino acids, total soluble sugars, reducing sugars, non reducing sugars, and proline by 27.25 %, 54.52 %, 14.06 %, 13.73 %, 14.11 % and 87.29 %, respectively but true protein and total carbohydrate decreased by about 43.38 % and 19.94 %, respectively as compared to no saline water (S1) treatment. Same trend of increase was observed with the progressive increase salicylic acid concentration from C1 to C3. Mean values of total phenol, true protein, free amino acids, total soluble sugars, reducing sugars, non reducing sugars, total carbohydrates and proline for salicylic acid treatment C3 (salicylic acid 200 ppm) showed increment as compared to no salicylic acid (C1) treatment. Enzyme activities were increased for all the enzymes studied due to saline water stress. The activities of enzymes like polyphenol oxidase, peroxidase and catalase increased by 83.04 %, 47.44 % and 17.37 %, respectively in treatment S3 as compared to S1 treatment. Mean values of polyphenol oxidase, peroxidase and catalase for salicylic acid treatment showed progressive increment from C1 to C3 treatment. So, salicylic acid can reduce the effect of saline water stress on all the biochemical parameters, physiological parameters and enzymetic acticities at some extent.