A critical review on physiological changes associated with reference to salinity

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 disastrous ionic phase that accelerates senescence of leaves. Plants may adapt to salinity with three different types as osmotic stress tolerance, Na+ or cr 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 metabolism, antioxidant enzymes, carbohydrates and minerals.