BIOPHYSICAL CHARACTERIZATION OF MAGNETIC FIELD INDUCED ENHANCEMENT IN CHICKPEA (Cicer arietinum L.) SEEDS IN RELATION TO SOIL MOISTURE STRESS

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Date
2009
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DIVISION OF AGRICULTURAL PHYSICS
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Experiments were conducted to study the effect of pre-sowing seed exposure to static magnetic field on two chickpea varieties with a view to understand their mechanism of action in terms of seed water absorption, root dynamics and growth and yield. A desi variety, Pusa 256 and on a kabuli variety, Pusa 1053 were selected for this study. Seeds of both varieties exposed to 100 mT static magnetic field for 1h, standardized by preliminary experiments were used as the starting material for all experiments. Temporal changes in seed water absorption in magnetically exposed seeds of both varieties had higher rate of absorption which may be attributed to magnetically induced greater seed membrane permeability to water. Seed water activity was greater for magnetically exposed seeds. This indicated that in treated seeds, not only seed water content increased, but also its corresponding water activity that resulted in early germination. Seed water diffusivity increased in general with time and in magnetically treated seeds, seed water diffusivity values were greater than untreated controls and hence better water absorption in these seeds. Dynamics of root characters under two soil water regimes (12 & 20%) clearly demonstrated consistent increases in all parameters in treated plants over unexposed control. The relative increase over untreated control was more for Pusa 1053 than Pusa 256. Periodic measurements in root and shoot weight and the length of the longest root in the same experiment also showed similar trend. Study conducted in pots maintained under -0.1 MPa and -0.2 MPa soil water potentials exhibited significant improvement for various physiological traits in plants grown from magnetically treated seeds and reduced significantly from flowering to podding stage and with soil moisture stress. Similar trend was observed for growth and root parameters. However, in plants from treated seeds, adverse effect of stress was ameliorated as they maintained relatively higher photosynthesis and leaf water status through osmotic adjustment and greater root length and root surface area. In both varieties, RUE and WUE decreased sharply under stress conditions. Magnetic field exposure has improved RUE and WUE over unexposed controls except for Pusa 1053 at -0.1 MPa potential. At harvest irrespective of magnetic treatment, drastic reduction in grain weight of stressed plants was observed but in well watered condition, plants from magnetically treated seeds produced more biomass, pod number and grain weight than untreated controls. It may be concluded that exposure to static magnetic field of 100 mT for 1h improved seed water absorption characteristics in desi and kabuli varieties of chickpea that resulted in early germination and early vigour of seedlings. Improved root system coupled with superior leaf water status led to increased photosynthesis in mature plants and produced greater biomass and grain weight. Also, when these plants were subjected to severe water stress (-0.2 MPa), the adverse effect was ameliorated partially by magnetic field treatment.
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t-8110
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