| Due to human activities such as industrial sewage irrigation,excessive fertilization and metallurgical mining,et al.Cd pollution in farmland is serious,and the problem of food safety is becoming increasingly prominent.Rice is the main food crop in China,and the Cd concentration in rice of some areas is seriously exceeded the current standards.In this study,“Huang Huazhan”was chosen as the experimental rice material to study the effects of short-term Cd stress on Cd uptake,nutrient elements and physico-biochemical properties of rice at seedling stage,and the effects of Zn or Mn on Cd uptake,transport and physiological indicators under Cd stress,in order to find out the role of Zn or Mn in rice seedlings during Cd stress,and to discuss whether this effect is related to the stress time,providing a theoretical basis for the control of Cd content in rice.The main conclusions are as follows:?1?The Cd content in rice roots is much higher than that in stems and leaves.The transport of Cd from the root to the above-ground part presented a phenomenon of“low promotion and high inhibition”.After 3 days of Cd stress,the transfer coefficient of Cd under low concentration(1.25?mol·L-1)was 2.05 times higher than that of Cd under high concentration(5?mol·L-1).?2?The CAT and APX enzymes showed different activities in rice leaves and stems.Compared with the treatment without Cd,after 3 days treatment with 5?mol·L-1Cd,the activities of CAT in rice leaves and stems increased by19.11%and 17.33%,respectively,and the activities of APX in both parts increased by 28.07%and 21.17%,respectively,indicating that the own antioxidant system of rice could resist the short-term Cd stress.?3?The addition of Cd and Zn promoted the uptake of Cd in all parts of rice,and the pretreatment with Zn could inhibit the transport of Cd to leaves.?4?Regardless of pretreatment with or without Mn,the simultaneous addition of Cd and Mn inhibited the transport of Cd to the leaves,and the pretreatment with Mn in advance had better inhibitory effect on the transport of Cd to the leaves.?5?Whenever Zn or Mn was added to rice,the growth of above-ground parts of rice could be promoted,the growth of under-ground parts could be inhibited,and the toxic effects of Cd on the above-ground parts of rice seedlings could be alleviated.Moreover,the mitigation effect of pretreatment with Zn or Mn in advance was better. |
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