Effect of silicate on the growth and arsenate uptake by rice (Oryza sativa L.) seedlings in solution culture

Abstract

A solution culture experiment was conducted to investigate the effect of silicate on the yield and arsenate uptake by rice. Rice seedlings (Oryza sativa L. cv. Weiyou 77) were cultured in modified Hoagland nutrient solution containing three arsenate levels (0, 0.5 and 1.0 mg L )1 As) and four silicate levels (0, 14, 28 and 56 mg L )1 Si). Addition of Si significantly increased shoot dry weight (P ¼ 0.001) but had little effect on root dry weight (P ¼ 0.43). Addition of As had no significant effect on shoot dry weight (P ¼ 0.43) but significantly increased root dry weight (P ¼ 0.01). Silicon concentrations in shoots and roots increased proportionally to increasing amounts of externally supplied Si (P < 0.001). The presence of As in the nutrient solution had little effect on shoot Si concentration (P ¼ 0.16) but significantly decreased root Si concentration (P ¼ 0.005). Increasing external Si concentration significantly decreased shoot and root As concentrations and total As uptake by rice seedlings (P < 0.001). In addition, Si significantly decreased shoot P concentration and shoot P uptake (P < 0.001). The data clearly demonstrate a beneficial effect of Si on the growth of rice seedlings. Addition of Si to the growth medium also inhibited the uptake of arsenate and phosphate by the rice seedlings.Abbreviation: ICP-OES -inductively coupled plasma-optical emission spectrometer

Is the effect of silicon on rice uptake of arsenate (AsV) related to internal silicon concentrations, iron plaque and phosphate nutrition?

“…Table 3 Parameters of kinetics for arsenate influx into rice (Oryza sativa L.) roots with four Si treatments to the ÀSi À Si treatment. This result is in agreement with our previous report (Guo et al, 2005). Si pretreatment with no As exposure (þSi À Si) had no beneficial effect on shoot dry weights compared to the ÀSi À Si treatment.…”

“…Si is also well known to be effective in alleviating abiotic stresses in higher plants (Hodson and Evans, 1995;Rogalla and Römheld, 2002;Liang et al, 2003Liang et al, , 2005. Our previous study demonstrated that addition of Si to the nutrient solution can decrease As uptake by rice seedlings (Guo et al, 2005). The mechanisms involved in the effect of Si on uptake of As are so far not clear.…”

Strong chemical evidence for high Fe(II)-colloids and low As-bearing colloids (200nm–10kDa) contents in groundwater and flooded paddy fields in Bangladesh: A size fractionation approach

“…The lower Si concentration in soil water likely reflected Si uptake by rice plants (Guo et al 2005). Fe(Tot) and the percentage of As-bearing colloids (% As coll) in soil waters (black circles), groundwaters (grey circles) and flooded surface water (cross).…”

“…Indeed, in the case of rice, As complexation by colloidal particles may significantly reduce its bioavailability for the plant by competitive effects between colloidal reactive sites and Asspecific sites (or Fe plaque) on the cell membrane of roots (Liu et al, 2004;Guo et al, 2005). Therefore, in the present paper, the leading role of such colloids was investigated through the occurrence of colloidal species and the impact of components such as Fe, Mn, PO 3À 4 and SiO 4À 4 on colloid formation.…”

Mechanisms of silicon-mediated alleviation of abiotic stresses in higher plants: A review

“…Over last two decades, more extensive and intensive studies have been performed aiming at better understanding of the possible mechanism(s) for Si-enhanced resistance and/or tolerance of higher plants to both abiotic and biotic stresses (Horst and Marschner, 1978;Horiguchi and Morita, 1987;Hodson and Evans, 1995;Liang, 1999;Epstein, 1999;Liang et al, 2003;2005a,c;Gong et al, 2005;Guo et al, 2005). More recently, rapid progress has been made in Si uptake and transport in higher plants.…”