Sajal Roy

By Sajal Roy and Nasrin Chowdhury

High salt concentration in soil is a major abiotic stress, which adversely influences the growth, overall development, and productivity of crops. More than 20% of the land of the world used for crop production is adversely affected by high salt concentration. The problem of salt stress becomes a major concern when previously fertile, productive agricultural lands are salinized more profoundly as a result of anthropogenic activities along with natural causes. Therefore, this review is focused on various aspects of salt-affected soils (SAS), their effects on plants, and different approaches for reclamation of SAS to enhance the potentiality for crop production. Salt-affected soils are categorized into saline, saline-sodic, and sodic soils based on the amount of total soluble salts as expressed by electrical conductivity (EC), sodium adsorption ratio (SAR), exchangeable sodium percentage (ESP), and soil pH. The inhibition of plant growth in saline soils is mainly induced by osmotic stress; reduced uptake of essential macro- and micronutrients, including nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu); and specific toxicities of sodium (Na) and chloride (Cl). Sodic soils adversely affect the plant through high soil pH and poor physical condition resulting from an excessive amount of exchangeable Na. Different plants respond to salt stress in different extents. Salt-affected soils must be reclaimed to restore their productivity for increasing food production. The approaches for the management of SAS include leaching, incorporation of different organic and inorganic amendments, mulching, and development of salt-tolerant crops. The suitability of approaches depends on several considerations such as cost of reclamation, the time required, the extent of the salt stress, soil properties, availability of technology, and other environmental factors. Among different strategies, the incorporation of organic amendments is beneficial, cost-effective, environment friendly, and sustainable for amelioration of salt stress and enhancement of crop production due to the extensive roles of organic amendments in improving the soil’s physical (structural stability, porosity, and permeability), chemical [pH, EC, ESP, organic matter, cation exchange capacity (CEC), and Na leaching], and biological and/or biochemical (microbial abundance, microbial activity, biomass carbon, and enzymatic activities) properties.

Part of the book: Abiotic Stress in Plants

By Sajal Roy and Nasrin Chowdhury

Soil salinity impedes the normal growth of plants by a number of mechanisms, including osmotic stress and imbalance absorption of essential nutrients. The present study focused on holistic approaches to the production of spinach (Spinacia oleracea L.) in clay loam acidic saline soils. In connection with this, spinach was grown in soils with two salinity levels (hereinafter referred to as soil A: high salinity and soil B: extreme salinity) in the presence of vermicompost (VC), wood ash (WA), and zeolite (ZL) applied at the rates of 1% and 2% (w/w) both alone and in combination along with N-P-K fertilizer. Results indicated better growth as well as the uptake of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sodium (Na) over control with significant (p < 0.01) differences when VC and WA were applied in combination. The Cshoot/Croot quotient of N, K, Ca, Mg, and Na was found greater than 1, whereas P was observed lower than 1. The Na: K, Na: Ca, and Na: Mg ratios were found to be highest in control that differed significantly (p < 0.01) from the rest of the amended soils. The present study suggests the combined application of VC and WA at the rate of 1% before cultivation to influence soil nutrient dynamics and plant growth in saline soils with acidic soil reactions.

Part of the book: Plant Defense Mechanisms