Arsenic toxicity to rice (Oryza sativa L.) in Bangladesh

Abstract

Natural contamination of groundwater with arsenic (As) occurs around the world but is most widespread in the river basin deltas of South and Southeast Asia. Shallow groundwater is extensively used in the Bengal basin for irrigation of rice in the dry winter season, leading to the possibility of As accumulation in soils, toxicity to rice and increased levels of As in rice grain and straw. The impact of As contaminated irrigation water on soilAs content and rice productivity was studied over two winter-season rice crops in the command area of a single tubewell in Faridpur district, Bangladesh. After 16-17 years of use of the tubewell, a spatially variable build up of As and other chemical constituents of the water (Fe, Mn and P) was observed over the command area, with soil-As levels ranging from about 10 to 70 mg kg −1 . A simple mass balance calculation using the current water As level of 0.13 mg As L −1 suggested that 96% of the added arsenic was retained in the soil. When BRRI dhan 29 rice was grown in two successive years across this soil-As gradient, yield declined progressively from 7-9 to 2-3 t ha −1 with increasing soil-As concentration. The average yield loss over the 8 ha command area was estimated to be 16%. Rice-straw As content increased with increasing soil-As concentration; however, the toxicity of As to rice resulted in reduced grain-As concentrations in one of the 2 years. The likelihood of As-induced yield reductions and As accumulation in straw and grain has implications to agricultural sustainability, food quality and food security in As-affected regions throughout South and Southeast Asia.

The Arbuscular Mycorrhiza Rhizophagus intraradices Reduces the Negative Effects of Arsenic on Soybean Plants

“…At present, soybeans are grown in prime soils and also in marginal lands, where the occurrence of some As-contaminated soils has been documented for many years [16]. Bustingorri et al [13] found a negative correlation between soybean yields and soil As concentration, in agreement with similar studies in rice, wheat, and barley [7,17].…”

“…Aerial biomass was less affected by As than roots in non-inoculated plants as described for rice, wheat [5,7,17], and soybeans [14]. Resembling the findings of other authors [26], inoculated plants were less affected by As.…”

Managing Water and Soils to Achieve Adaptation and Reduce Methane Emissions and Arsenic Contamination in Asian Rice Production

“…The yield decline was associated with a decrease in the number of productive tillers. The authors note, also, that while arsenic concentrations in the rice grain were relatively high, ranging from 0.3 mg per kg to 0.6 mg per kg, concentrations in rice straw were much higher, ranging from about 2 mg per kg to 12 mg per kg [285].…”

“…High arsenic concentrations can contribute to the development of straighthead disease, which can cause sterility after heading, in otherwise healthy rice plants [284]. Panaullah et al [285] observed a grain yield gradient on a rice field irrigated from a tubewell for 16 years in Bangladesh. During two crop seasons, grain yields declined from about 8000 kg per ha to 2500 kg per ha, as the concentration of total arsenic in the soil, across the field, increased from about 12 mg per kg to 70 mg per kg.…”

“…High concentrations in rice straw raise additional concerns regarding arsenic exposure, as rice straw is the primary feed material for cattle and buffalo in Bangladesh, and manure is burned in kitchens to provide fuel for cooking [285]. Ghosh et al [286] report high concentrations of arsenic in drinking water and rice straw, and in cow's urine, dung, and milk in areas of Bangladesh with high concentrations of arsenic in groundwater.…”