Arsenic Shoot-Grain Relationships in Field Grown Rice Cultivars

Abstract

Arsenic (As) accumulation in rice grains is a risk to human health. The mechanism of transfer of As from the shoot into the grain during grain filling is unknown at present. In this study As speciation in the shoot and grains at maturity were examined, and the relationships between phosphorus (P) and As, and silicon (Si) and As were established in a wide range of cultivars grown in As contaminated field trials in Bangladesh and China. No correlations were observed between shoot and grain speciation, with the inorganic form comprising 93.0-97.0% of As in the shoot and 63.0-83.7% in the grains. The percentage of dimethylarsinic acid (DMA) was between 1.4 and 6.6% in the shoot and 14.6 and 37.0% in the grains; however, the concentrations were comparable, ranging from 0.07 to 0.26 mg kg -1 in the shoots and 0.03 to 0.25 mg kg -1 in the grains. A positive correlation was observed between shoot As and shoot Si, however, no correlation was observed between shoot Si and grain As. A significant negative correlation was observed between shoot P and grain As concentrations. These results suggest that the translocation of As into the grain from the shoots is potentially using P rather than Si transport mechanisms. The findings also indicate that inorganic As and DMA translocation to the grain differ considerably.

Accumulation of Heavy Metals in Different Parts of Wheat Plant from the Yangtze River Delta, China

“…Cr is the least accumulated heavy metal in all plant parts. These results suggest that the accumulation of Cd in soil and wheat is significant in Kunshan City and the potential risks of Cd to humans are higher than that of other HMs because Cd can easily complex with OH − and Cl − in soil (Norton et al, 2010).…”

“…The accumulation capacity of different wheat plant parts on identical or different HMs varies, because of the different functions of various wheat plant parts or the different natures of various HMs in wheat (Romkens et al, 2009;Norton et al, 2010;Ru et al, 2010). Among the studied plant parts, the roots have the strongest accumulation capacity for HMs.…”

“…These factors can determine the combined form and transfer capability of HMs in soil-plant systems (Dai et al, 2009;Zheng et al, 2015). The heavy metal accumulation capability of plants in soil mainly depends on the heavy metal concentration in soil and the genetic characteristics of plants (Huang et al, 2008;Norton et al, 2010;Ye et al, 2013). The accumulation of HMs in various plant parts is also related to the transport mechanisms of HMs in plants.…”

“…For example, Ren et al (2012) studied the effects of concentration of single heavy metal Zn or Cd on growth of wheat and rice by a pot experiment; Nie et al (2012) studied effects of 5 HMs (Cd, Pb, As, Hg, Cr) stress on wheat yields and ingredient in farmlands; Su et al (2010) explored the heavy metal pollution and migration in soil-wheat system under the condition of using different livestock manure. Based on existing research, main conclusions of accumulation in soilcrop system are as follows: Different plants have different heavy metal accumulation ability, Different plants have different translocation and accumulation ability to the same heavy metals (Ro Mkens et al, 2009;Norton et al, 2010;Ye et al, 2013). Now, the current research on HMs mainly focused on the repair and treatment of HMs, physiological mechanisms of pollution remediation and risk assessment of pollution etc.…”

The effect of different water managements on rice arsenic content in two arsenic-spiked soils

“…The conventional water management (CK) showed higher As level in husk but no significant difference in brown rice compared to other three aerobic treatments. This difference can be explained by the rice physiologic mechanism (Norton et al, 2010).…”