مقاله انگلیسی رایگان در مورد پاسخ فیزیولوژیکی گندم به تنش خشکی – اسپرینگر 2018

Plants have always been a key to survival for humans, as they are vital to meet the world’s food needs by contributing about 82% to total global food production harvested from land resources. Historically, over 3000 species of plants have been used to feed humans. Among the plants, wheat is an excellent health building food and an excellent source of minerals, dietary fber, proteins, and B-group vitamins. It is often grown in rain-fed areas (Geravandi et al. 2011) for its starch and protein that makes it the most important cereal crop globally, and, along with rice and maize, forms an integral part of diets of over 4.5 billion people. The success of wheat in temperate world regions is due to its adaptability and high yields together with its unique four dough properties which give it a distinct advantage over the other temperate crops (Shewry 2007). Drought is a polygenic stress (Kilic and Tacettin 2010) that reduces productivity and quality of crops (Waraich et al. 2010, 2011) and also limits the successful realization of land potential throughout the world (Pierre et al. 2012; Liu et al. 2016). The scarcity of water, caused by erratic and poorly distributed rainfall, causes tremendous global losses in agriculture. Russia, for example, has estimated total losses of over US$800 million due to drought and other natural challenges in 2000 alone. Drought afects all plant development stages from germination, vegetative and reproductive growth to grain flling and maturation of the crop (Hossain et al. 2012). Drought reduces nitrogen (N) uptake efciency and utilization by plants. The deprived nutrient uptake is due to impaired membrane permeability and active transport and reduced transpiration rate resulting in repressed root absorbing power. In semi-arid and arid regions of the world, drought is one of the leading causes of limited agriculture production. Many growth variables and functions of plants are afected by water stress (Nezhadahmadi et al. 2013). Under drought conditions, the intake of CO2 is reduced due to stomatal closure, and inside the stomata, a high level of oxygen produces reactive oxygen species, caused by the partial reduction of oxygen, and causes rupturing of membranes which become leaky, thereby afecting respiration, photosynthesis, and the overall development of the plant. Reactive oxygen species also seriously damages the production of cellular components such as carbohydrates, nucleic acids, lipids, and proteins (Waraich et al. 2011; Reddy et al. 2014). Drought is one of the major abiotic stresses that afect at least 60% of wheat production in high-income countries and about 32% of 99 million hectares in low-income least developed countries (Chen et al. 2012). Water defcit might decrease wheat grain yield from 17 to 70% (Nouri-Ganbalani et al. 2009). Daryanto et al. (2016) reported 20.6% yield losses in 40% reduced water. Double ridge to anthesis stage is the most sensitive growth period regarding wheat yield to water defcit because of the negative infuence on number of spikelets and ultimately kernels per spike. Water defcit decreases grain yield by afecting anthesis and grain flling period. It is well documented that plant height, biomass, and yield are more sensitive traits to water defcit in comparison with number of spikes and 1000 grain weight.