Salinity refers to the saltiness or quantity of salt in the water soil or water body measured in parts per thousand. Some of the signs that indicate that salinity is at a higher levels in plants include small stunted fruits, slowed and stunted growth, amplified succulence of leaves, darker leaves or bluish green and dropping of leaves as well as yellowing, browning, and mottling (Willey, 2016). Plants get the majority of the water and nutrients from the soil thus when salinity increases they use more energy to draw water via the roots making it dehydrate even when there is sufficient water since it cannot maintain the effort needed to replenish the water supply.
Salts can prohibit plant growth and development by decreasing the capability to obtain water or causing injuries to the cells. Since plants absorb nutrients via the root system, a lot of salts will be obtained in regions with high salinity disrupting the cellular function (Thomas & Murray, 2016). Moreover, the salt particularly impacts the layer of tissue in the branching of the root system leading to the production of stress hormone that prohibits root growth. Furthermore, high amounts of sodium can cause leaf death hence decreasing the photosynthetic capability of the plant causing the slowed growth or even death. Besides, salinity affects the growth of plants by impacting the environment outside the roots and inside the plant. The osmotic stress initiated by salt solution decreases the leaf development and growth, lesser extent root enlargement and reduces the stomatal conductance (Willey, 2016). The rate at which new leaves are generated depends massively on the water potential in the soil similar to that of drought-stressed plants. However, salts do not concentrate in the growing tissues but rapidly elongating cell may accommodate the salt that comes from the xylem in the expanding vacuoles.
The salt in the plant promotes the senescence of the previous leaves. The continued movement of salt into the transpiring branches and leaves for a long time leads to high levels of chloride and sodium concentrations hence causing death (Thomas & Murray, 2016). The rate of leaf death is vital for the survival of plants. However, the production of new leaves in the saline conditions is below that of dying leaves which decreases the photosynthesis resulting in reduced growth rate. The increase of salt around the plant roots creates the osmotic phase or water stress making it hard for the plant to obtain water. The osmotic pressure in the plant roots decreases while that in the soil or saline solutions increases thus making hard for water to move into the cells due to the augmented osmotic gradient (Willey, 2016). Photosynthesis refers to the process of making foods in green plants by using water, carbon dioxide, and sunlight. Since photosynthesis takes place in leaves, the dying, yellowing, dropping and browning results to the decreased amount of food in the plant causing wilting and slowed growth. For a plant to survive in saline conditions, it must maintain the high water status in the soil with water shortages and potential ion toxicity. Plants retain only two percent of the water that is transpired thus they obtain about fifty times more water from the environment through the roots than they keep in the tissues (Willey, 2016). Based on the results, the hypothesis is correct since salinity affects the growth of plant negatively.