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20101
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Subject: Botany × Author: Kaur, Jasdeep × End date: 2010 × Start date: 2010 ×
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    REGULATION OF SENESCENCE THROUGH THE APPLICATION OF PLANT GROWTH REGULATORS AND NUTRIENTS IN RELATION TO PRODUCTIVITY IN SOYBEAN (Glycine max L. Merrill)
    (Punjab Agricultural University, Ludhiana, 2010) Kaur, Jasdeep; Kaur, Jagmeet
    Soybean called ‘Miracle Bean’ belongs to family Fabaceae, contains 40% proteins and 20% edible oil. A striking feature of maturing soybean is decline of assimilatory capacities due to growing reproductive structures and is characterized by syndrome of physiological changes that include decline in foliar N, protein, chlorophyll and photosynthetic activity culminating in leaf abscission. The regulatory signals exchanged between the parts of soybean plant during development are affected by endogenous levels of hormones and possibly nutrient fluxes. The exogenous application of plant growth regulators and nutrients was done to study the senescence behavior in soybean. The treatments comprised of control (no spray), foliar application of SNP @150 and 200 µM, ethrel @ 150 and 200 µgml-1, calcium chloride @ 1 and 2 mM and sodium selenite @10 and 20 µgml-1. The treatments were applied in combinations of three stages vis-à-vis preflowering (V), pod initiation (P) and grain filling (G). Various observations pertaining to the morpho-physiological, biochemical and yield attributes were recorded at various growth stages. The morpho-physiological traits vis-à-vis plant height, root length, leaf characteristics, canopy characteristics and biomass accumulation studied at 60, 80, 100 and 120 DAS; were effectively enhanced by V+P+G application of SNP 200µM and P+G application of sodium selenite 20µgml-1. Also, the application of SNP 200µM (V+P+G) and sodium selenite 20µgml-1 (P+G) gave best results in terms of yielding attributes viz. pod count, 100 seed weight and seed yield. The photosynthetic pigments and activity along with storage biomolecules (total soluble sugars and starch) exhibited maximum change with SNP 200µM (V+P+G) and sodium selenite 20µgml-1 leading to enhanced production of photosynthates and accumulation of photoassimilates. The activities of antioxidant enzymes vis-à-vis catalase, peroxidase and superoxide dismutase concomitant with proline accumulation was putatively enhanced with the application of SNP 200µM (V+P+G) and sodium selenite 20µgml-1 (P+G) thereby counteracting the senescence induced oxidative stress. Also, the treatment with SNP 200µM elicited the activation of high molecular weight proteins in the leaves at 80 DAS. Conversely, higher concentration of ethrel at all treatment combinations depicted reduction in morpho-physiological traits, intense loss of chlorophyll and membrane integrity, lesser production of sugars and starch and reduced antioxidants contributing towards much reduced yield. Therefore, NO donor SNP 200µM (V+P+G) and sodium selenite 20µgml-1 (P+G) behaved as anti-senescence growth substance.