Organic Amendments for Mitigation of Salinity Stress in Plants: A Review.

Natural and/or human-caused salinization of soils has become a growing problem in the world, and salinization endangers agro-ecosystems by causing salt stress in most cultivated plants, which has a direct effect on food quality and quantity. Several techniques, as well as numerous strategies, have been developed in recent years to help plants cope with the negative consequences of salt stress and mitigate the impacts of salt stress on agricultural plants. Some of them are not environmentally friendly. In this regard, it is crucial to develop long-term solutions that boost saline soil productivity while also protecting the ecosystem. Organic amendments, such as vermicompost (VC), vermiwash (VW), biochar (BC), bio-fertilizer (BF), and plant growth promoting rhizobacteria (PGPR) are gaining attention in research. The organic amendment reduces salt stress and improves crops growth, development and yield. The literature shows that organic amendment enhances salinity tolerance and improves the growth and yield of plants by modifying ionic homeostasis, photosynthetic apparatus, antioxidant machineries, and reducing oxidative damages. However, the positive regulatory role of organic amendments in plants and their stress mitigation mechanisms is not reviewed adequately. Therefore, the present review discusses the recent reports of organic amendments in plants under salt stress and how stress is mitigated by organic amendments. The current assessment also analyzes the limitations of applying organic amendments and their future potential.

5-aminolevulinic acid-mediated plant adaptive responses to abiotic stress.

KEY MESSAGE: 5-aminolevulinic acid (ALA) modulates various defense systems in plants and confers abiotic stress tolerance. Enhancement of crop production is a challenge due to numerous abiotic stresses such as, salinity, drought, temperature, heavy metals, and UV. Plants often face one or more abiotic stresses in their life cycle because of the challenging growing environment which results in reduction of growth and yield. Diverse studies have been conducted to discern suitable mitigation strategies to enhance crop production by minimizing abiotic stress. Exogenous application of different plant growth regulators is a well-renowned approach to ameliorate adverse effects of abiotic stresses on crop plants. Among the numerous plant growth regulators, 5-aminolevulinic acid (ALA) is a novel plant growth regulator, also well-known to alleviate the injurious effects of abiotic stresses in plants. ALA enhances abiotic stress tolerance as well as growth and yield by regulating photosynthetic and antioxidant machineries and nutrient uptake in plants. However, the regulatory roles of ALA in plants under different stresses have not been studied and assembled systematically. Also, ALA-mediated abiotic stress tolerance mechanisms have not been fully elucidated yet. Therefore, this review discusses the role of ALA in crop growth enhancement as well as its ameliorative role in abiotic stress mitigation and also discusses the ALA-mediated abiotic stress tolerance mechanisms and its limitation and future promises for sustainable crop production.