دانلود رایگان مقاله انگلیسی پاسخ فیزیولوژیکی گندم به تنش خشکی و رویکرد های کاهشی آن - اشپرینگر 2018

Abstract

Drought is a polygenically controlled stress and a major agricultural risk that reduces crop productivity and limits the successful insight of land potential throughout the world. This review article has been divided into two parts, i.e., efect of drought stress on physiology of wheat and potential drought mitigation approaches. In the frst part, physiological responses of wheat to stress were discussed. Cell membrane stability, relative water content, early maturity, decreased leaf area, small plant size, increased dry weight and root–shoot ratio, and the whole-plant transpiration rate response to enhanced atmospheric vapor pressure defcit are physiological traits associated with drought tolerance in wheat. Reduction of relative water content closes stomata and thereby reduces stomatal conductance. Osmotic adjustment improves drought tolerance by allowing cell enlargement, plant growth, and stomata to stay partially open and by maintaining CO2 fxation under severe water defcit. The wheat plant accumulates several organic and inorganic solutes in its cytosol to lessen its osmotic potential for maintenance of cell turgor. Drought afects photosynthesis negatively by changing the inner structure of chloroplasts, mitochondria, and chlorophyll content and minerals. Destruction of the photosystem II (PSII) oxygen releasing complex and reaction center can disturb production and use of electrons, causing lipid peroxidation of cell membrane through the production of reactive oxygen species. In the second part, drought mitigation approaches were discussed. Seed, drought, bacterial, and hormonal priming are common approaches used to lessen the efects of water defcit. Physiological trait-based breeding, molecular breeding, marker-assisted backcrossing, aerial phenotyping, water budgeting, and resource allocation are modern approaches used to develop drought tolerant wheat cultivars. Wheat genotypes produced as a result of a combination of all these methodologies will increase food security regarding the currently changing climate.

Future outlook and main conclusions

The implications of water shortages around the globe will continue to worsen with signifcant challenges to food production. The challenges brought on by climate change and variability in the world due to global warming will likely have negative impacts on the global grain production, in particular on the crops that feed the world—wheat, rice, and maize. Continued research needs to focus on the use of climate smart agriculture technologies that will reduce the deleterious efects of the stresses. Almost in every part of the globe, crops are grown under suboptimal conditions, thereby limiting their potential, and reducing food availability. The most afected people are the smallholder farmers who live on less than US$2 day−1, who fail to meet their food demand, causing poverty, hunger, and decreased health. Wheat supports billions of people directly and indirectly and is a staple food for millions of individuals globally. Among several other constraints including heat and low soil fertility, drought poses signifcant yield losses in wheat and also reduces wheat quality. These stresses impose biochemical, structural, and morphological changes in wheat causing yield losses. The implications of drought will have a highly negative impact on millions of people who depend on wheat directly for their calories.

Low-cost feld phenotyping through easy to handle tools of drought tolerance-related characters should be used as an essential strategy in the breeding pipeline. Advancement in technology in terms of phenotyping equipment should also be considered along with strategies used to describe and control variation in the feld for wheat under water defcit. It can be achieved using suitable experimental designs, choice of the true characters, and, fnally, an appropriate combination of diverse datasets, analysis, and applications, including forecast models. A well-organized combination of all components is required for further application of high-throughput phenotyping to develop drought tolerant wheat varieties in future.