Toxic Effect of Cadmium on Rice as Affected by Nitrogen Fertilizer Form

Abstract

A nutrient solution experiment was conducted to determine the influence of N forms on growth, oxidative stress, and Cd and N uptake in rice plants. The treatments were consisted of two Cd levels (0 and 1 lmol) and three N forms (NH 4 ) 2 SO 4 , NH 4 NO 3 and Ca(NO 3 ) 2 . The results indicated that without Cd addition in the culture solution, the N forms had no significant effect on all measured parameters, including plant growth, photosynthetic traits, malondialdehyde (MDA) concentration, superoxide dismutase (SOD) activity, and Cd and N concentration, while Cd addition in the medium resulted in significant differences in measured parameters among the three forms of N fertilizers. The least inhibition of growth was noted in (NH 4 ) 2 SO 4 -fed plants, and the largest in Ca(NO 3 ) 2 -fed plants, when plants were exposed to Cd stress. The highest photosynthetic rate and chlorophyll content was also recorded in (NH 4 ) 2 SO 4 -fed plants. Addition of Cd caused a remarkable increase in SOD activity and MDA content in plants, and the extent of increase varied with N form, with (NH 4 ) 2 SO 4 -fed plants being smallest. In comparison with the control plants, the N concentration in roots and shoots was not significantly affected in (NH 4 ) 2 SO 4 -fed plants, but significant decrease in root N concentration was found for the NH 4 NO 3 and Ca(NO 3 ) 2 -fed plants under Cd stress. Moreover, the significant differences were also noted among the three N forms in both root and shoot Cd concentrations, with (NH 4 ) 2 SO 4 -fed plants being the lowest. The results indicated that the toxic effect of Cd on rice varied with the form of N fertilizer.

Effects of nitrogen on the activity of antioxidant enzymes and gene expression in leaves of Populus plants subjected to cadmium stress

“…However, that nitric oxide (NO) acts as a bioactive signaling molecule in plant responses to heavy metal stress has been reported in many studies (Hassan et al 2005;Floryszak-Wieczorek et al 2006;Grün et al 2006;Arasimowicz & Floryszak-Wieczorek 2007). It was documented that exogenous NO reduces the destructive action of heavy metals, ethylene, and herbicides on plants (Kopyra & Gwózdz 2003).…”

“…As soon as the balance is broken, the overaccumulation of ROS in plants leads to significant damage to the membrane system of plants from a lipid peroxidation reaction, which can increase permeability and conductivity (Gallego et al 1996;Chaoui et al 1997;Kaya et al 2013). Although plant growth, chlorophyll content, stomata opening, transpiration, and photosynthesis have been reported to be inhibited by Cd in nutrient solutions (Jiang & Li 1992;Baryla et al 2001;Drążiewicz & Baszyński 2005;Sun et al 2005), there have also been reports that Cd treatments had no effect on photosynthesis or growth (Greger & Lindberg 1986;Haag-Kerwer et al 1999;Li et al 2005;Zhou & Qiu 2005), and that N was possibly a bioactive signaling molecule in plant responses to heavy metal stress (Hassan et al 2005;Floryszak-Wieczorek et al 2006;Grün et al 2006;Arasimowicz & Floryszak-Wieczorek 2007). However, despite all these studies, the precise mechanisms of how extra N alleviates the toxic symptoms caused by Cd stress remain unknown.…”

Nitrogen as an important detoxification factor to cadmium stress in poplar plants

“…According to related research, the detoxification strategies may include: (1) Regulation of metal uptake by the root system (Hart et al 1998;Benavides et al 2005;Hassan et al 2005); (2) Constraint by the cell wall (Hart et al 1998); (3) The presence of some chelate complexes, such as phytochelatin-Cd Quan et al 2006;Gustavo et al 2007); (4) Regulation of related gene expression (Benavides et al 2005;Xu et al 2006;Wu et al 2012). Especially, sequestration with glutathione (GSH) and phytochelation (PC) is an important pathway to detoxifying Cd, which has earlier been confirmed (Singhal et al 1987).…”

“…Sedum alfredii Hance is a plant tolerant to cadmium and zinc (Yang et al 2004) The important physiological role of N in detoxifying plants from heavy metals has not been studied. However, the nitric oxide acting as bioactive signaling molecule in plant responses to heavy metal stress has been reported in many studies (Hassan et al 2005;Floryszak-Wieczorek et al 2006;Grü n et al 2006;Arasimowicz & Floryszak-Wieczorek 2007). The exogenous nitric oxide reducing the destructive action of heavy metals, ethylene and herbicides on plants was documented (Kopyra & Gwo´zdz 2003).…”

Root excretion and plant tolerance to cadmium toxicity - a review

“…Application of (NH 4 ) 2 SO 4 and sulphate fertilizers would induce vulcanization in soil to produce much H 2 S, which contributes to formation of CdS. Hassan et al (2005) also found that the toxic effect of Cd on rice varied with the form of nitrogen fertilizer, and application of (NH 4 ) 2 SO 4 to Cd stressed rice plants, compared to NH 4 NO 3 or Ca(NO 3 ) 2 , would be beneficial to mitigate detrimental effect of Cd and to reduce Cd accumulation in plants.…”