Drought stress, which causes a decline in quality and quantity of crop yields, has become more accentuated these days due to climatic change. Serious measures need to be taken to increase the tolerance of crop plants to acute drought conditions likely to occur due to global warming. Drought stress causes many physiological and biochemical changes in plants, rendering the maintenance of osmotic adjustment highly crucial. The degree of plant resistance to drought varies with plant species and cultivars, phenological stages of the plant, and the duration of plant exposure to the stress. Osmoregulation in plants under low water potential relies on synthesis and accumulation of osmoprotectants or osmolytes such as soluble proteins, sugars, and sugar alcohols, quaternary ammonium compounds, and amino acids, like proline. This review highlights the role of osmolytes in water-stressed plants and of enzymes entailed in their metabolism. It will be useful, especially for researchers working on the development of drought-resistant crops by using the metabolic-engineering techniques.
Global climate changes cause extreme temperatures and a significant reduction in crop production, leading to food insecurity worldwide. Temperature extremes (including both heat and cold stresses) is one of the most limiting factors in plant growth and development and severely affect plant physiology, biochemical, and molecular processes. Biostimulants like melatonin (MET) have a multifunctional role that acts as a “defense molecule” to safeguard plants against the noxious effects of temperature stress. MET treatment improves plant growth and temperature tolerance by improving several defense mechanisms. Current research also suggests that MET interacts with other molecules, like phytohormones and gaseous molecules, which greatly supports plant adaptation to temperature stress. Genetic engineering via overexpression or CRISPR/Cas system of MET biosynthetic genes uplifts the MET levels in transgenic plants and enhances temperature stress tolerance. This review highlights the critical role of MET in plant production and tolerance against temperature stress. We have documented how MET interacts with other molecules to alleviate temperature stress. MET-mediated molecular breeding would be great potential in helping the adverse effects of temperature stress by creating transgenic plants.
Abstract:The development of intensive horticulture in Almería, with a huge increase in greenhouse surface area, is related to three essential factors: climatic characteristics, groundwater use and mulching sandy soil. The purpose of the present paper is to draw a picture of the integral management of water irrigation in the intensive horticultural systems in the region, by identifying the most significant water resource contributions and alternative water resources. Results indicate that the use of groundwater for the irrigation of horticultural crops in the greenhouses presents a high degree of overexploitation of the aquifers, but due to the continuous search for alternative water resources, such as desalinated and reclaimed water, as well as in-depth knowledge of the integral management of water irrigation through automated fertigation and localized irrigation systems, the current status of the water resources could be sustainable. Moreover, being conscious of the pollution generated by agricultural leachates, the horticultural system of Almería is implementing complementary sustainable systems such as recirculation, cascade cropping systems and phytodepuration for the reuse of the leachate. Considering all these factors, it can be concluded that the intensive horticultural system is on the right path towards respecting the environment and being sustainable in terms of water use.
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