| Heavy metal cadmium(Cd) pollution has become one of the serious environmental issues in the world.In order to clarify the physiological responses of naked oat(Avena nuda) to Cd stress and accumulation characteristics of Cd,in this study,we took Dingyou 6,a naked oat variety,as the material.The seeds were treated with different concentrations of Cd2+(0,5,10,25,50 and 100 mg·L-1),and soil pot experiment with five different Cd concentrations(0,5,10,25 and 50 mg·kg-1 in the soil) was conducted to study the effects of Cd stress on the seed germination,photosynthesis,reactive oxygen metabolism,Cd accumulation and plant growth of naked oat.The results showed that Cd stress had no effect on germination rate and germination index of naked oat seeds,but the inhibition on vigor index,radicle length and seedling dry weight were enhanced with the increase of Cd2+ concentration.With increase of soil Cd2+ concentration,photosynthetic pigment content,net photosynthetic rate,stomatal conductance and transpiration rate were all decreased,but intercellular CO2 concentration,O-[KG-*2]·2,H2O2 and malondialdehyde contents were increased,and superoxide dismutase and catalase activities were increased and then decreased.Peroxidase activity showed a trend of rising,falling and rising,ascorbate peroxidase activity and ascorbate content decreased gradually,while glutathione content increased continuously in leaves of naked oat at heading stage.Cd concentration and accumulations in root and shoot of naked oat at heading stage was increased gradually with the soil Cd concentration increasing,while accumulative factor and translocation factor were decreased.In addition,the plant height,yield and yield components of naked oat at the mature period were decreased significantly with increase of soil Cd concentration.These results revealed that Cd stress inhibits the formation of healthy seedlings and the accumulation of Cd in plants,induces the disturbance of reactive oxygen metabolism and the reduction of photosynthesis in leaves,as well as the growth inhibition and yield reduction of naked oat. |
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