“INFLUENCE OF BRASSINOLIDE AND SALICYLIC ACID ON BIOCHEMICAL CHANGES DURING GROWTH AND DEVELOPMENT, YIELD & SEED QUALITY OF GROUNDNUT”
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Date
2007-07
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JAU, JUNAGADH
Abstract
A field experiment was conducted to assess the response of salicylic acid and brassinolide on various metabolites during growth and development, yield and its attributes and quality of groundnut kernels. Salicylic acid, the phenolic compound and brassinosteroids are a new addition to the group of plant growth regulators (PGRs) and have emerged as the sixth group of phytohormones in plants, as evidenced by their significant growth promoting properties and their influence on varied physiological & biochemical processes. The present investigation was undertaken with an objective to find out the effects of exogenous application of these growth regulators on growth, yield and metabolism of groundnut. Foliar spray of 300 and 500 ppm salicylic acid (SA) as well as 10 and 15 ppm brassinolide (BS) was done at vegetative (20 days after sowing) and reproductive stages (40 days after sowing) of the cultivar GG-7 and growth, yield, yield attributes and biochemical parameters were measured.
Contents of soluble protein, total DNA, RNA, free amino acids and activities of nitrate reductase, polyphenol oxidase and peroxidase were measured in leaves of groundnut during growth and development. SA @ 300 ppm was more effective in case of nitrate reductase whereas free amino acid, peroxidase activity, polyphenol oxidase activity were maximum with the spray of SA @ 500 ppm. BS @ 10 ppm was more effective in case of soluble protein and total DNA whereas maximum increase of total RNA was recorded with BS @ 15 ppm. Thus, soluble protein, DNA and RNA content during growth and development were altered are highly responsive with the application of brassinolide treatment. Whereas free amino acid, nitrate reductase, peroxidase and polyphenol oxidase activity were altered with the application of salicylic acid during growth and development. Kernel quality was improved with both the growth regulators as statistically significant enhancement of total protein, free amino acid, reducing sugar, non-reducing sugar, total carbohydrate, total soluble sugar, total phenol and free fatty acid content in groundnut kernel was observed. 15 ppm BS was effective in case of reducing sugar, non-reducing sugar, total carbohydrates, total soluble sugars, total phenol and free fatty acid, whereas oil content in groundnut kernel was non significant with both the growth regulators. BS @ 10 ppm was more effective in case of total protein content whereas free amino acid content was effective with SA at 300 ppm.
All the yield attributing factors viz. pod yield, biological yield, 100 kernel weight, total number of mature pods per plants and shelling outturn were significantly enhanced with growth regulators treatments as compared to control whereas harvest index was not altered with the application of these growth regulators. BS @ 10 ppm concentration was more effective in case of pod yield, biological yield, 100 kernel weight, total number of mature pods per plant and shelling outturn.
Considering the overall effect of growth regulators concentration, it was observed that both the concentrations of brassinolide (10 and 15 ppm) equally exerted their influence, however, in case of salicylic acid, the lower concentration (300 ppm) was more effective in comparison with the higher one (500 ppm).
No marked influence of stages of application on growth was noticed in the present study. However, spraying of growth regulators at vegetative stage was better in terms of total DNA, free amino acid, peroxidase and NR activity whereas in case of soluble protein, total RNA and polyphenol oxidase activity the spray at reproductive stage exerted more influence. In case of kernel quality parameters, spraying of growth regulators at vegetative stage was better in terms of total protein, total phenol, total carbohydrates and reducing sugar content in groundnut kernel whereas in case of free fatty acid, total soluble sugar, non-reducing sugar and free amino acid content, spray at reproductive stage exerted more influence. Spraying of growth regulators at vegetative stage was better in terms of biological yield and shelling outturn whereas in case of pod yield, 100 kernel weight and total number of mature pods per plants, spray at reproductive stage exerted more influence.
Significant positive correlation was observed between pod yield and total RNA (leaf), Total protein (kernel), 100 kernel weight, and total number of mature pods per plant. BS @ 10 ppm and SA @ 300 ppm significantly enhanced the pod yield in groundnut vis a vis important biochemicals, kernel quality and yield attributing characters.
Thus, distinct favourable effect of growth regulators could be distinguished as evidence by increased growth metabolites in the treated plants. This coupled with the enhanced metabolic rate of the bioregulators treated plants resulted in greater pod production, indirectly enhanced the yield. The results very well confirm the role of salicylic acid and brassinolide as the growth regulators.
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Biochemistry