SALICYLIC ACID-INDUCED BIOCHEMICAL CHANGES AGAINST ROOT-KNOT NEMATODE (Meloidogyne incognita) IN CHICKPEA, Cicer arietinum (L.)
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Date
2002
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AAU, Anand
Abstract
Investigations were carried out at the Departments of Biochemistry and Nematology, B.A.College of Agriculture, G.A.U., Anand during rabi 2001-2002, to study the effect of exogenous salicylic acid on the induction of resistance through biochemical changes in chickpea, Cicer arietinum (L.) against root-knot nematode (Meloidogyne incognita). Study on development of PR proteins by exogenous SA revealed that SA applied as seed treatment was found to be more effective in inducing PR proteins in chickpea seedlings compared to foliar spray or their combinations. Another experiment was conducted to study the effect of SA on different resistance inducing biochemical parameters viz., sugars, amino acids, proteins, phenols and enzymes using three methods of SA application viz., seed treatment, seed treatment + spray and foliar spray. The results conclusively proved that although the application of SA in all the three methods, effectively enhanced production of all biochemical parameters under study in chickpea. However, seed treatments produced more significant effects than the other treatments. Among the different concentrations used under each method of application, 1500 ppm was more effective followed by 1000 ppm and 500 ppm. This implies that resistance in plant against M. incognita increases with increase in concentration of SA, irrespective of the method of application. Enzyme activities of peroxidase and polyphenol oxidase increased more at later stages of growth (45 & 60 DAS) in contrast to enzyme activities of phenylalanine amonia lyase (PAL), Tyrosine ammonia lyase (TAL) and β-glucosidase in the initial growth stages (30 & 45 DAS). Total soluble sugars decreased with increase in plant age whereas free amino acids, proteins and phenols increased with plant age. No isozymes of peroxidase were detected in both root and leaves due to the SA treatments. All these biochemical changes brought about by the application of SA induced resistance in chickpea against M. incognita which was observed by a decrease in the root-knot index. The third experiment organized to study the effect of SA in inducing resistance at two inoculum levels of M. incognita, showed no significant variation in total phenols and enzyme activities of peroxidase, polyphenol oxidase and phenylalanine ammonia lyase with increase in the inoculum level. The decrease in the root-knot index due to the SA treatments was more at lower inoculum level (1000 J2/plant) than at higher inoculum level (10,000 J2/pIant). All the three experiments conclusively proved that exogenous SA induced plant defence mechanism in chickpea by various biochemical changes which effects the life cycle and development of M. incognita.
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BIOCHEMISTRY, AGRICULTURE, A Study