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- Author or Editor: P. Rajkumar x
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Using a simple and novel semi-hydroponic technique, three experiments were carried out to evaluate salinity tolerance in twelve pipe-line/commercial maize hybrids at the seedling stage. For experiment 1, hybrids were evaluated at 0.10, 0.15 and 0.20 M NaCl. For experiments 2 and 3, hybrids were subjected to 0.25 and 0.30 M NaCl, respectively. The technique simulates a semi-hydroponic system where the upper layers of coco peat medium receive water/or saline solution only by capillary movement, while the roots are immersed in saturated lower coco peat medium. The emergence percentage ranged from 73 to 100% under control conditions, from 50 to 100% at 0.10 M NaCl, from 46 to 100% at 0.15 M NaCl and from 43 to 96% at 0.20 M NaCl. In addition, increasing salinity decreased the shoot and the root length and the seedling dry weight. Several hybrids (VMH 4029, VMH 4028, VMH 4088, VMH 4060, VMH 4033, VMH 4046, VMH 4101) exhibited a high emergence percentage of 80–96% even at 0.3 M NaCl, revealing that these hybrids have high salinity tolerance and also the capacity to produce high yields. This confirms that salinity tolerance and high yield may be combined if pipe-line hybrids which have been confirmed for high yield over multilocation trials are selected and then tested under field conditions in saline-prone areas.
Abstract
River sediment depositions on the bottom of rivers most frequently consist of sand and gravel particles, which make them particularly valuable for the building construction. Knowledge of radioactivity present in building material enables one to assess any possible radiological hazard to mankind by the use of such materials. The natural radionuclide (238U, 232Th and 40K) contents have been analyzed for the recently excavated sediment samples of Cauvery, Vellar, Ponnaiyar and Palaru rivers with an aim of evaluating the radiation hazard nature. To know the radiological characteristics of the sediment, the different radiological parameters are calculated. Natural radioactivity level is higher in Palaru river and it is lower in Vellar river sediments. In all the rivers, concentration of 238U is decreased, and concentrations of 232Th and 40K are increased towards the river mouth. Granulometric analysis shows that the sand is the main constituent in all the river sediment samples. Content of sand is gradually decreased, and contents of silt and clay are gradually increased towards the river mouth. Cluster analysis was carried out to find the similarity level between the radioactivity and granulometric measurements. The radioactivity level of all the four river sediments mainly depends upon the contents of silt and clay. Averages of the all calculated radiation hazard indices are lower than recommended level in Cauvery, Vellar and Ponnaiyar river sediments. Therefore, the sediment of the above rivers does not pose any significant radiological threat to the population when it is used as a building construction material.