Effect of varying concentrations of salinity on some biochemical parameters involved in nitrogen metabolism of four grass species

ABSTRACT: Salinity adversely affects crop productivity and the quality of yield. The present work was carried out to estimate the changes in nitrogen metabolism under the influence of NaCl salinity in four selected grasses. All the species recorded a decrease in nitrate nitrogen content at the highest concentration of salinity stress (300 mM). Its maximum increase was 14 and 19% (100 mM) for Cymbopogon nardus and Cynodon dactylon, respectively. The maximum increase in nitrite nitrogen found was 11% (200 mM) in Cymbopogon nardus, 12% (100 mM) in Cynodon dactylon. The concentration of proline and amides in the leaves of all the experimental grasses showed a positive correlation with increasing concentrations of salinity. The maximum increase in proline content was 81, 88, 126, and 68% in Cymbopogon nardus, Cynodon dactylon, Pennisetum alopecuroides, and Vetiveria zizanioides, respectively, at 300 mM NaCl salinity. The concentration of free amino acids in the leaves of all the experimental grasses was considerably increased under saline condition and showed a positive correlation with increasing concentrations of salinity. Similar results were obtained in the case of amides. The concentration of nitrate reductase enzyme was elevated in Cymbopogon nardus and Pennisetum alopecuroides at lower salinity regime

IPA-Open access -Distributed under Creative Commons Attribution License 2.0 A critical review on physiological changes associated with reference to salinity A critical review on physiological changes associated with reference to salinity

ABSTRACT Soil salinity is abiotic stress which adversely influences on growth, overall development and productivity of plants. The plant response to salinity consists of numerous morphological and cellular changes which function in a well coordinated way to alleviate toxicity and changes therefore. Adaptation of some species to elevated salt concentrations provides evidence for inherent potential existed in plants to survive under unfavorable conditions. It is well identified that tolerance and yield constancy are multifaceted genetic characters and are difficult to establish in crops since salt stress may occur as a disastrous. Salt stress may occur immediately, slowly or continually which may again differ in dose as periodically or gradually become severe during any stage of the life cycle of the plants. Therefore research strategies have to be developed to make the plants adaptable to saline environment to face diverse conditions at any stage of growth. Plant growth and internal changes responds to salinity by a way of rapid osmotic phase which inhibits growth of leaves by hampering photosynthesis and another slower but distraous ionic phase that accelerates senescence of leaves. Plants may adapt to salinity with three different types as osmotic stress tolerance, Na + or Cl -exclusion and by the way of tissue tolerance to sodium and chloride ions. Nowadays, plant physiology, cell biology and molecular genetics research are providing new insights into the plant response to salinity and to improve tolerance of plants relevant to food production and environmental sustainability. Further improvement in tolerance to salinity may be definitive to find out the genetic resources more easily with the understanding of physiological mechanisms concerned in controlling the responses to stress and also if the plants indicate salt tolerance at morphological or cellular level, selection becomes a suitable applied method. This will definitely give a hand in choosing the wonder plant species for the breeders and to overcome a challenging problem of salinity. Better management of soil resource with wise practices with the tolerant and adaptive varieties could be used successfully for raising crop productivity especially in the areas where salinity is consistent and with huge economic loss to the farmers. Therefore, an understanding of appropriate physiological mechanisms controlling stress tolerance so as to provide plant breeders with appropriate selection criteria is essential. The present review elucidates the biochemical changes and associated reasons of the parameters mainly growth, photosynthesis, polyphenols, nitrogen metanbolis, antioxidant enzymes, carbohydrates and minerals

Inertia friction welds between nickel superalloy components : analysis of residual stress by eigenstrain distributions

Machining, surface treatment, plastic forming and stretching, welding, and other manufacturing processes introduce residual stresses and distortion into work pieces and engineering components. These phenomena exert a significant influence on the behaviour of components affecting the response to thermal/mechanical in-service loading, e.g. in terms of crack initiation and propagation under the conditions of creep and fatigue, thus ultimately affecting their durability. In the present study, the inertia friction welding process is considered that is used for butt joining of hollow cylindrical components, such as shafts and drums. An inverse eigenstrain framework is used for the interpretation of neutron diffraction measurements in terms of the underlying eigenstrain distributions. Eigenstrain distributions that describe the nature of permanent inelastic deformation are found by minimizing the sum-of-squares measure of the disagreement between model prediction and experimental measurements of residual elastic strains. Experimental data obtained from neutron diffraction measurements are used in an inverse solution scheme in order to determine the underlying eigenstrain (strains permanently 'locked in') that give rise to the residual stress state. Once these are found, approximate reconstruction of the complete stress tensor within the entire component becomes straightforward. Eigenstrain distributions are first obtained for reduced size test specimens which have been characterized in detail using neutron diffraction. Subsequently, the eigenstrain distributions are scaled and applied to more complex, full-size real engine components, with scaling factors adjusted to match surface hole drilling measurements. © 2009 IMechE