外源硅增强水稻幼苗耐盐性机理分析OA

To explore the mechanism underlying the enhancement of salt tolerance in rice seedlings by exogenous silicon,a hydroponic experiment was conducted using Nipponbare as the test material.3 treatments were established,namely the nutrient solution group(CK),the 0.5%NaCl nutrient solution group,and the 3 mmol/L Na₂SiO₃+0.5%NaCl nutrient solution group.The salt injury symptoms,growth parameters(including seedling length,root length,etc.)and physiological and biochemical indices[including catalase(CAT)activity,malondialdehyde(MDA)content,etc.]were determined for each treatment.A pot experiment was performed for verification,with Lianjing 7 and Lianjing 15 as the test materials.4 rice seedling raising substrate treatments were set up:seedling raising substrate(control),seedling raising substrate+Na₂SiO₃,seedling raising substrate+1/2 diatomite,and seedling raising substrate+1/4 diatomite,followed by salt stress treatment with 0.5%NaCl for all substrate groups.The seedling growth status and salt ion concentration distribution were observed across the 4 treatments.The results showed that in the hydroponic experiment,the salt injury indices of rice seedlings under the NaCl treatment and the NaCl+Na₂SiO₃ treatment were 63.0%and 41.2%,respectively.After 3 days of salt stress treatment,all the tested indices of the NaCl treatment group were significantly lower than those of the CK group(P<0.05),except for the shoot dry weight;the root length,shoot fresh weight,root fresh weight and root dry weight of the NaCl+Na₂SiO₃ treatment group were significantly higher than those of the NaCl treatment group(P<0.05).After 7 days of salt stress treatment,all the growth indices of rice seedlings under the NaCl treatment were significantly lower than those under the CK treatment(P<0.05);the root length,root fresh weight and the length of the third leaf in the NaCl+Na₂SiO₃ treatment group were significantly higher than those in the NaCl treatment group(P<0.05).Compared with the CK treatment,the NaCl treatment resulted in a significant decrease in CAT activity(P<0.05)and a significant increase in MDA content in both leaves and roots(P<0.01);in contrast,the NaCl+Na₂SiO₃ treatment caused a significant increase in leaf CAT activity(P<0.05)and a significant decrease in MDA content compared with the NaCl treatment(P<0.01).In the pot experiment,the severity of salt injury symptoms among all treatments followed the order of NaCl>NaCl+1/2 diatomite>NaCl+1/4 diatomite>NaCl+Na₂SiO₃.Compared with the NaCl treatment,the application of exogenous silicon(in the form of Na₂SiO₃ and diatomite)led to a significant decrease in Na⁺ content in rice seedling roots(P<0.01),while the Na⁺ content in leaves(except for the fifth leaf)was significantly increased with the Na₂SiO₃ treatment(P<0.01).Overall,the results demonstrate that salt stress causes damage to rice plants by inhibiting growth processes and interfering with oxidase activity,whereas the application of exogenous silicon can improve the salt tolerance of rice seedlings and alleviate salt stress by regulating antioxidant enzyme activity and salt ion distribution.