Effects of silicon nutrition on cadmium uptake, growth and photosynthesis of rice plants exposed to low-level cadmium

Abstract

The effect of silicon (Si) nutrition on lowlevel cadmium (Cd) toxicity symptoms was investigated in hydroponically-grown rice seedlings (Oryza sativa L.). Silicon (0.0, 0.2, or 0.6 mM) was added when seedlings were 6 or 20 days old representing early (Si E ) or late (Si L ) Si treatment, respectively. Cadmium (0.0 or 2.5 μM) was added when seedlings were 6 days old. Measurements included generation of CO 2 and light response curves; chlorophyll fluorescence analysis; growth; and tissue-element content analysis. Our results showed that low-level Cd treatment generally inhibited growth and photosynthesis. However, the addition of 0.2 or 0.6 mM Si E or Si L significantly reduced root-and leaf-Cd content. Consequently, the addition of 0.6 mM Si L significantly alleviated lowlevel Cd-induced inhibition of growth. Furthermore, 0.2 mM Si treatment significantly reduced g s compared to 0.0 or 0.6 mM Si without inhibiting A, especially in +Cd plants, suggesting an increase in instantaneous water-use-efficiency (IWUE). Additionally, in +Cd plants, the addition of 0.6 mM Si E significantly reduced F o but increased F v /F m , while treatment with 0.2 mM Si L significantly increased q P , suggesting an increase in light-use-efficiency. We thus, propose that 0.6 mM Si L treatment is required for the alleviation of low-level Cd-mediated growth inhibition. Furthermore, we suggest that 0.2 mM Si concentration might be close to the optimum requirement for maximum Siinduced increase in IWUE in rice plants, especially when under low-level Cd-stress. Our results also suggest that Si alleviates low-level Cd toxicity by improving light-use-efficiency. Keywords Chlorophyll fluorescence . Instantaneous water-use-efficiency . Low-level cadmium . Silicon . Stomatal conductance Abbreviations A net CO 2 assimilation rate A max maximum net CO 2 assimilation rate C a ambient CO 2 concentration C E carboxylation efficiency C i intercellular CO 2 concentration E transpiration rate F m maximum chlorophyll fluorescence yield in a dark-adapted state F o minimum chlorophyll fluorescence yield in a dark-adapted state F o /F m basal quantum yield of non-photochemical processes in PS2 in a dark-adapted state F v maximum variable fluorescence yield in a dark-adapted state F v /F m quantum efficiency of open PS2 centers in a dark-adapted state Plant Soil (2008) 311:73-86

Effect of silicon application on Sorghum bicolor exposed to toxic concentration of zinc

“…Mitigation effect of Si was determined in maize plants grown at 0.2 mM Zn concentration in nutrient solution (Kaya et al 2009). Consistent data are known for Cd+Si treated rice (Nwugo & Huerta 2008). Similarly, Si improved the growth of maize exposed to Cd (Vaculík et al 2009).…”

“…For example, Si plays an important role in increasing the resistance of plants to pathogenic fungi (Fauteux et al 2005;Resende et al 2009). Silicon also mitigates cadmium inhibitory effects in rice and maize plants (Nwugo & Huerta 2008;Vaculík et al 2009). This positive influence also has been recorded in the case of other metals and plant species, e.g.…”

Effects of Silicon on Alleviating Arsenic Toxicity in Maize Plants

“…Silicon was also effective in alleviating Cr stress by increasing the concentrations of photosynthetic pigments and the efficiency of chlorophyll fluorescence parameters (Ali et al, 2013). Silicon application increased quantum efficiency of open PS2 centers in a dark-adapted state (Fv/Fm) and photochemical quenching coefficient in a lightadapted state (qP) parameters in rice plants under Cd stress (Nwugo and Huerta, 2008a).…”

Effect of Modified Bentonite on Cd Accumulation in Different Organs and Growth of Rice under Cadmium Stress

“…He studied the effects Cd stress on seed germination, seeding growth and seed amylase activities in rice, the results showed than Cd stress had bad influence on these indexes [7]. Cd stress also had some influence on enzymes and photosynthesis in growing rice seedlings [8,9]. Wet biomass of T5 and T6 was significantly higher than that of T4 which showed that MB could prevent rice from destroy under Cd stress.…”