Malaysian Journal of Sustainable Agriculture (MJSA) 5(2) (2021) 67-76 Quick Response Code Access this article online Website: www.myjsustainagri.com DOI: 10.26480/mjsa.02.2021.67.76 Cite the Article: Bipin Rijal, Prakash Baduwal, Madhukar Chaudhary, Sandesh Chapagain, Sushank Khanal, Saugat Khanal, Padam Bahadur Poudel (2021). Drought Stress Impacts on Wheat And Its Resistance Mechanisms. Malaysian Journal of Sustainable Agriculture, 5(2): 67-76. ISSN: 2521-2931 (Print) ISSN: 2521-294X (Online) CODEN: MJSAEJ RESEARCH ARTICLE Malaysian Journal of Sustainable Agriculture (MJSA) DOI: http://doi.org/10.26480/mjsa.02.2021.67.76 DROUGHT STRESS IMPACTS ON WHEAT AND ITS RESISTANCE MECHANISMS Bipin Rijal a* , Prakash Baduwal a , Madhukar Chaudhary a , Sandesh Chapagain a , Sushank Khanal a , Saugat Khanal b , Padam Bahadur Poudel a a Institute of Agriculture and Animal Science, Paklihawa, Rupandehi, Nepal. b Faculty of Agriculture, Agriculture and Forestry University, Rampur, Chitwan, Nepal. *Corresponding Author email: rijalbpin@gmail.com This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ARTICLE DETAILS ABSTRACT Article History: Received 20 November 2020 Accepted 24 December 2020 Available online 06 January 2021 Scarcity of water has been a serious agricultural hindrance to crop productivity since antiquity. Drought- stressed loss in wheat yield likely exceeds losses from all other causes, since both the severity and duration of the stress are censorious. Here, we have reviewed the effects of drought stress on the morphological, physiological, and biochemical attributes along with the growth impacts, water relations, and photosynthesis impacts in wheat. This review also illustrates the mechanism of drought resistance in wheat. Historical drought years in Nepal have been identified and the yield losses were assessed. Wheat encounters a variety of morphological, physiological, biochemical responses at cellular and molecular levels towards prevailing water stress, thus making it a complex phenomenon. Drought stress affects leaf size, stems elongation and root proliferation, imbalance plant-water relations and decline water-use efficiency. Different types of physiological research are ongoing to find out the changes occurs in the wheat plant as a result of drought stress. Morphological changes can be looked through two ways: changes in root system and changes in shoot system such as effects on height, leaf senescence, flowering, and so on. Physiological changes involve changes in cell growth pattern, chlorophyll contents, photosynthetic disturbances, plant-water relations, etc. Biochemical changes occur in different chemical, biomolecules, and enzymes. Plants portray several mechanisms to withstand drought stress which can be classified as Drought escape, Drought avoidance, and Drought tolerance. Selection of wheat genotype that can tolerate water scarcity would be suitable for the breeding program aiming to development of drought tolerant variety under water limited regions. KEYWORDS Agronomic changes, Drought, Nepal, Resistance, Wheat. 1. INTRODUCTION Wheat, Triticum aestivum, is one of the most widely cultivated cereals, particularly in the mediterranean region and other semi-arid regions from temperate to subtropical areas of the world (Ahmed et al., 2019). Most of the areas of land in which wheat is cultivated lie in arid and semiarid regions. A key determinant in the favorable outcome of wheat is its adaptation to a broad range of climatic conditions. Approximately, one- third of the global population uses wheat as a staple crop and also the first cereal crop in majority of the developing countries (Bayoumi, 2009). It serves as an essential food source, as it contains carbohydrates, dietary proteins, fiber, calcium, zinc, fats, and energy. However, in many countries, including Nepal the attainable yield hasn’t been achieved through there is high potential of enhancing the average yield. Wheat is mostly cultivated under rainfed conditions where fluctuations in rainfall pattern have caused water insufficiency to act as a determining factor for declining the crop yield, especially when water deficit stress occurs during the flowering and grain filling period stages (Bassi et al., 2017). The likeliness of drought stress in the coming days is high owing to global climate change and declines in availability of underground water resources for agriculture. It has been proved through many researches that wheat production is drastically affected by abiotic stresses. A study reported that for every 1-degree centigrade increase in temperature, there is a yield loss of about 4.1% to 6% (Liu et al., 2016). Salinity contributes to the reduction of wheat yield (Mujeeb-Kazi et al., 2019). On the other hand, drought is considered as major menace to wheat yield and is gaining much attention nowadays. By 2025 it is anticipated that nearly 1.8 billion people will face absolute water shortage and 65% of the world’s population will face water-stressed environments (Nezhadahmadi et al., 2013b). The factor limiting the wheat production in many regions is primarily due to erratic rainfall, reducing average yield up to 50% and often over. Wheat can be produced in a varied range of agro-climatic environments; nevertheless, most of these environments have drought stress as one of the major constraints to their production and yield. The predicted global warming and climatic fluctuations will increase the frequency of drought, therefore leads to the losses of the wheat yield. The increase in annual average temperature accompanied with fluctuations in rainfall patterns and arising drought risks in many regions have impacted agricultural