Authors: Nidhi jain1 , Ravi kumar2 ,Usha sharma3
1Assistant professor, tantia university sriganganagar
2Research scholar Department of Plant Breeding and Genetics, SKN college of Agriculture, Jobner
3Assistant professor, Tantia University Sriganganagar
Salinity is one of the most important environmental factor limiting plant growth. plant salt stress is a condition where excessive salts in soil solution cause inhibition of plant growth or plant death. No toxic substance restricts plant growth more than does salt, salt stress presents an increasing threat to plant agriculture. Among the various sources of salt salinity, irrigation combined with poor drainage is the most serious. Because it represents losses of once producing agricultural land.Salt stress can affect plant survival, biomass, plant height and plant morphology and affect the capacity of a plant to collect water and nutrients. A study on global land use pattern reveals that 7 per cent of the world’s land area, amounting to 1000 million hectares has become saline. In India, about 30 million hectares of coastal land remain barren and uncultivable because of saline soil. High levels of soil salinity can cause water deficit, ion toxicity and nutrient deficiency leading to molecular damage and even plant death Salinity can also affect plant growth because the high concentration of salts in the soil solution interferes with balanced absorption of essential nutritional ions by plants. Salinity of the soil and water is caused by the presence of excessive amount of salt. Most commonly, high Na+ and Cl- cause the salt stress. Salt stress has three fold effects; viz. it reduces water potential and causes ion imbalance or disturbances in ion homeostasis and toxicity.
The level of expression of salt tolerance by plant at germination stages cannot always be correlated with tolerance at later stages of development. Halophytes survive salt concentration equal to or greater than that of seawater and possess physiological mechanism that maintains a lower water potential than that in the soil Many studies have assessed responses to sudden increases in external salinity. Although halophytes can adjust to sudden changes in external salinity over a period of 24–48 h as in other plants, initial responses to an up shock are presumably to the osmotic component of the imposed NaCl treatment. Changes in turgor can be rapidly transmitted throughout plants, but how this change is sensed is still uncertain. It must also be questionable whether pressure sensing would be effective in halophytes if these plants operate at low turgor. As Na+ and Cl− enter the cytosol, these ions are presumably also sensed, but again how this is achieved is not known. However, we are still ignorant of the metabolic adaptations and direct physiological processes of halophytes that enable them to survive under saline conditions. Apart from algae and few ferns, all salt tolerant green plants belong to the angiosperms. Halophytes are widely distributed among the families of flowering plants and this suggests a polyphyletic origin of salt tolerance. It has been found that about 129 families of flowering plants comprising 500 genera and 1500 species are of halophytic origin In the present investigation, effect of different concentrations of NaCl on the commonly occurring halophytes in Pichavaram mangrove area Suaeda maritima with regard to its growth and development organic and inorganic components, photosynthesis pigments and the activity of certain key enzymes was studied. The upper limit of the salt for the survival of the seedlings of Suaeda maritima and the optimal level of salinity for its favourable growth and development were also assessed.
Salinity is a major abiotic stress limiting growth and productivity of plants in many areas of the would due to increasing use of poor quality of water for irrigation and soil salinization.
Adverse effect of salinity stress
- High salinity interferes with plant growth and development and can also lead to physiological drought conditions and ion toxicity.
- The basic physiology of high salinity stress as a high salt deposition in soil leads to a deposition of a low water potential zone in the soil. this makes increasingly difficult for the plant to acquire water as well as nutrients.
- Salinity causes ion- specific stress resulting in an altered K/Na ratio.
- Salinity leads to a buildup of Na+ and Cl- concentrations in the cytosol, which can be ultimately detrimental to the cell.
- Higher concentrations of sodium ions can also leads to a reduction in photosynthesis and the production of reactive oxygen species.
- High salinity can also injure cells in transpiring leaves, which leads to growth inhibition. This salt- specific or ion- excess effect of salinity causes a toxic effect of salt inside the plants.
References:
1. Munns, R.A., and lauchli, A.(2006). Approaches to increasing the salt tolerance of wheat and other cereals. Exp. J. Bot.57,1025-1043.
2. Zhu, J.K.(2002). Salt and drought stress signal transduction in plants. Annu. Rev. plant Biol.53,247-273.
About Author / Additional Info:
I am working in Tantia university , Sriganganagar as a assistant professor of plant breeding and Genetics