Effects of different water management on absorption and accumulation of selenium in rice

Abstract

Rice is the staple food for more than half of the world's population, but selenium (Se) is low in many rice growing countries. Water management model affects rice soil pH and Eh, and then affects the bioavailability of Se in soil. A pot experiment was conducted to investigate the effects of water management on soil Se species, dynamics and selenium uptake by rice plants. Sodium selenite was added to the soil so that the soil selenium content reached 0.5 mg kg to study the effects of 3 different water management modes on soil selenium uptake by rice plants. These three modes are flood irrigation (F), aerobic irrigation (A) and alternate flood and aerobic irrigation (AFA). The results showed that flooded irrigation treatment increased the soil soluble selenium concentration, and the selenium in soil solution mainly existed in the form of selenite and selenomethionine selenium oxide. The content of selenium in grain was 2.44 and 1.84 times that of flooded irrigation treatment under A and AFA respectively. The content of selenium in straw was 1.32 and 1.58 times that of flooded treatment under A and AFA respectively. After rice grain enzyme hydrolysis, HPLC-ICP-MS analysis showed that Selenomethionine was the main selenium speciation in rice grains. This study showed that aerobic flooded treatment is one of the most effective ways to increase selenium content in rice field.

Selenium Biofortification and Interaction With Other Elements in Plants: A Review

“…Selenite is a weak acid, which can exist in different forms under varying pH and Eh (Zhou et al, 2018;White, 2018). Different absorption mechanisms for Se(VI) appear to be in operation under different pH regimes.…”

Tuning of the Amount of Se in Rice (Oryza sativa) Grain by Varying the Nature of the Irrigation Method: Development of an ICP-MS Analytical Protocol, Validation and Application to 26 Different Rice Genotypes

“…In particular, the Se bioaccumulation in rice grain irrigated aerobically seems largely higher on soil supplemented with selenate rather than in that supplemented in selenite. More recently, the study of Zhou et al [49] (one rice genotype, soil supplemented with Na 2 SeO 3 up a final concentration in Se of 0.5 mg kg −1 and three water management techniques, i.e., the traditional flooded irrigation and two intermittent techniques) confirms the tendency to increase of Se bioaccumulation in rice grain when aerobic irrigation was used, while flooded irrigation is effective in minimizing the concentration of Se in kernels. Albeit the undoubted interest in these results, their application in a real situation looks quite questionable, due to some specific features of their relevant experimental plans.…”

“…In order to overcome these opposite threats, different methodological approaches have been adopted in order to enhance the Se amount in rice from low-Se soils [33][34][35][36][37], whereas the reduction of the bioaccumulation of Se in rice grain cultivated in Se-rich soils has been accomplished by cultivating low Se-bioaccumulating rice genotypes [38] or by means of phytoremediation techniques [39]. Although the adoption of water management techniques different from the continuous flooding (i.e., the traditional technique of irrigation for rice, still used worldwide) has been proven to be effective in modulating the bioaccumulation phenomena of toxic elements like As [40][41][42][43] and Cd [44][45][46][47] in rice grain, at the best of our knowledge a very scarce attention was until now paid to study the influence of changes in the method of irrigation of rice on its Se concentration [48,49]. Only two pot studies performed first by Li and coworkers [48] and-more recently-by Zhou and coworkers [49] drew attention to the effectiveness of intermittent methods of irrigation (i.e., the so-called "aerobic irrigation" [48,49] and the "alternate flood and aerobic irrigation" [49]) on the bioaccumulation of Se in rice grains.…”

“…Although the adoption of water management techniques different from the continuous flooding (i.e., the traditional technique of irrigation for rice, still used worldwide) has been proven to be effective in modulating the bioaccumulation phenomena of toxic elements like As [40][41][42][43] and Cd [44][45][46][47] in rice grain, at the best of our knowledge a very scarce attention was until now paid to study the influence of changes in the method of irrigation of rice on its Se concentration [48,49]. Only two pot studies performed first by Li and coworkers [48] and-more recently-by Zhou and coworkers [49] drew attention to the effectiveness of intermittent methods of irrigation (i.e., the so-called "aerobic irrigation" [48,49] and the "alternate flood and aerobic irrigation" [49]) on the bioaccumulation of Se in rice grains. However, the paucity of agronomic details provided in describing both these irrigation techniques, as well as a number of meaningful differences in the relevant experimental plans make the results obtained somehow incoherent among them, if not even contradictory.…”

Water resource management for sustainable development

“…The integration of wastewater quality and vulnerability into the design and planning of water management strategies are needed. Numerous researchers have addressed the strategic topic of water resource management, especially for agriculture (Al-Saidi 2017; Christ and Burritt 2017; Gao et al 2017;Liu et al 2017;Nguyen et al 2018;Ross 2017;Skouteris et al 2018;Zhou et al 2017). It is well known the agriculture accounts for more than two thirds of the global water use (Kraiem et al 2014).…”