The Research On Response To Cadmium Stress And Transport Process Of Rice Under Infection Of Arbuscular Mycorrhizal Fungi

Now "cadmium rice" problem has caused widespread concern at home and abroad, cadmium pollution has become the main culprit threaten our food security because of its large range of hazards and undercover features, not only resulted in poor growth of rice, but also seriously affected the quality of rice food safety. Currently, the vast majority of cadmium contaminated areas are still engage in farming activities, changes in farming methods can not solve the transfer of heavy metals to crops fundamentally. Searching for a safe and effective method of in situ repair, to achieve safe sustainable use of slightly polluted soil is the new ideas in responsing the current large-scale soil heavy metal pollution.For the situation, we choose rice as experimental materials, two kinds of widespreading and friendly used Arbuscular Mycorrhizal Fungi(AMF)-Glomus mosseae(GM) and Glomus intraradices(GI) to be the inoculum strains. According to the typical sewage concentration of cadmium conte nt areas and soils environmental quality, we set seven cadmium concentration pollution gradient, in order to quantitatively analyze the efficacy of AMF in prompting the growth of rice, photosynthesis and reproductive growth, as well as cadmium content in rice plants and seeds. Findind cost-effective ways to reduce the cadmium content of rice seed and provide practical countermeasure for the safe production of rice under low cadmium condition.The results show that the inoculation of AMF can significantly improve rice root infection rate, and remain stable in different cadmium stress. With cadmium content increase, plant height and root length show a downward trend, while AMF can relieve the inhibition of rice growth under cadmium stress. The order of rice leaf dry weight under different cadmium conditions is GM> GI> CK, and in contrast with blank control group, GM increase by 10.76%—59.48%,GM can remarkably improve rice biomass and the trend of underground dry weight remain consistent. Within the range of 5 mg·kg-1, root shoot ratio of rice reduce slowly, so AMF at low concentrations of cadmium stress will have a strong protective effect.Utilization rate of light will be improved by AMF infection, promoting photosynthesis and carbon accumulation in rice. With the increase level of Cd stress, Pn is significantly inhibited. At 20 mg·kg-1 cadmium condition, Pmax of GM、GI and blank control group reduce 34.62%, 33.05% and 47.23% respectively compared with 0 mg·kg-1. Water use efficiency decrease slowly at first and then accelerate the trend with increasing concentration of Cd. Under 2000μmol·m-2·s-1 light intensity, WUE of GM and GI will be improved by 14.57% and 10.42% respectively compared with blank group. AMF infection makes some stress-related physiological indicators tend to be normal, which protect rice favorable growth and physiological characteristics under cadmium stress. Cd Stress in Rice causes a decreasing trend in rice yield, while AMF inoculation can ease the stress caused by Cd of decline in rice yield and would provide a strong guarantee.Under different concentrations of cadmium treatment, the absorption coefficient of AMF inoculated rice is higher while bio concentration factor and translocation factor are lower than the blank control group. When cadmium concentration is higher than 1 mg·kg-1, cadmium content in rice grains are lower that inoculate GM compared with CK. Suggesting that infection agents can significantly enhance the rice root cadmium fixed capacity, and weaken its transport and accumulate ability to the ground stems and leaves parts. At non-ionculated conditions, soil cadmium content less than 0.12 mg·kg-1 may achieve safe production, while after inoculate GM the soil cadmium content of rice production safety will be increased to 0.21 mg·kg-1.To sum up, AMF could significantly improve rice root infection rate and enhance plant height, root length, biomass growth index and so on. Promot ing rice for light use efficiency thereby improve rice yield. Thus alleviate cadmium stress caused by physiological damage to rice, and it plays an important role in the regulation of cadmium in rice plants absorb and transport process, which improve the production of rice cultivation security in mild soil cadmium contamination environment.