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| Studies on Physiological Response of Watercress to Cd Stress and Its Cd Accumulation |
| HAN Cheng-hua，ZHOU Zeng-hui，ZHANG Na，JIANG Jie-zeng * |
| Institute of Aquatic Vegetable Research， Yangzhou University， Yangzhou 225009， Jiangsu， China |
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Abstract A hydroponic experiment was carried out to study the effects of Cd on the growth of watercress（
Nasturtium officinale R. Br.）．The indexes under treatments of different Cd concentration，
such as agronomic characters，yield，root activity，net photosynthetic rate（ Pn），antioxidant enzyme
activity and the concentration of malondialdehyde（ MDA），phytochelatins（ PCs） and Cd contents
changes at different parts of watercress were studied. The results showed that low Cd concentration would
influence watercress growth，i.e. the accumulation of MDA would rise，while high Cd concentration
would lead to the decline of root activity and Pn．Antioxidases and PCs played a cooperative role in alleviating
Cd toxicity. But the alleviation was dominated by PCs chelation under the condition of low Cd
concentration，while it would be dominated by the antioxygenation of SOD，POD，CAT along with the
increase of Cd concentration. Cd is easily accumulated in watercress．The Cd concentration in edible
parts of watercress had exceeded the limit value of national standards，when the concentration of Cd in
the nutrient solution reached 0.20 mg·L-1．In conclusion，watercress is a vegetable of Cd-sensitive
type，more attentions should be paid on Cd pollution during its production.
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Received: 22 September 2013
Published: 25 October 2013
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