Читать книгу Physiology of Salt Stress in Plants - Группа авторов - Страница 26

The soil salinization is one of the three soil degradation processes that pose a threat to human health and crop productivity by affecting more than one billion hectares land across the globe (Ondrasek et al. 2011). The negative effect of salt stress on crop productivity indirectly affects the economy dependent on the agricultural produce, resulting in the loss of billion dollars annually. The economic loss caused by the salt stress can include two components: first, the loss of crop productivity (presented in t/ha) and thus, the loss of income generated from the agricultural production and, second, the cost spent for the restoration of degraded land. Estimating the global loss due to soil salinization can be heterogeneous among the different countries or geographical regions because of factors such as labor costs, the market price of the agricultural produce, fertilizers, seeds, and other operational costs affecting the total input and income differentially. There is the possibility that in some regions of the world (developed countries), even the moderate salinization of the soil could result in higher economic loss due to higher operational and labor costs. In many developing countries, most of the poor farmers depend on agriculture for their livelihood and loss of crop productivity due to salt stress affects their livelihood. In Asia, the Maldives is a low‐lying country, always on risk of submergence due to increasing sealevel and salt deposition. The intrusion of seawater on its land area due to Tsunami and deposition of toxic salts caused degradation of more than 70% of the agricultural land (FAO 2005; Ondrasek et al. 2011). The salt deposition destroyed more than 3 70 000 fruit trees, with an estimated loss of AU $ 6.5 million, which affected around 15 000 farmers economically. In a previous report by Qadir et al. (2014), the total estimated economic loss globally was more than the 27 billion US dollars per year. The loss of productivity among the crop also varied depending upon their genetic makeup, for example, moderate salt stress of 8–10 dS/m results in the yield losses of 15%, 28%, and 55% in cotton, wheat, and corn cultivars, respectively (Satir and Berberoglu 2016; Zörb et al. 2019), showing that cotton performs better at moderate salt stress; however, at the higher salt stress, the cotton also became susceptible, and the yield loss at the 18 dS/m resulted in a 55% loss in cotton productivity (Satir and Berberoglu 2016). The yield loss estimation by salt stress in comparison with the healthy growth conditions in some of the major crops of Indian subcontinent revealed the loss of yield by 45, 39, 63, and 48%, in rice, wheat, cotton, and sugarcane, respectively (Qadir et al. 2014; Tripathi 2009), which again suggest the variation in yield losses could be the result of combined effects of many factors such as the cultivars used for the cultivation, environmental condition of that specific area, and extent and time of exposure to the saline soil conditions.