作 者 ：陈娜 廖 敏 张楠 徐培智 解开治 徐昌旭 刘光荣
期 刊 ：植物营养与肥料学报 2014年 20卷 3期 页码：651-660
关键词：亚铁离子；水稻生理指标；土壤微生物量；土壤微生物量碳；
Keywords:ferrous ions, rice physiological indices, soil microbial amount, soil microbial biomass C,
摘 要 ： 通过盆栽试验，模拟冷浸田土壤亚铁毒害，研究了土壤-水稻-亚铁-微生物相互作用的体系中，外加Fe2+ 不同处理水平 (0、 100、 200、 400、 800和1600 mg/kg) 对水稻苗期和分蘖期相关生理指标、 土壤微生物活性及其生态特征的影响。结果表明， 在含一定亚铁本底（207.77 mg/kg）的正常稻田土壤中，外源性Fe2+的加入将逐步抑制水稻生长、 降低土壤微生物活性。外源Fe2+浓度达100 mg/kg后，水稻的株高、 干物质积累量显著降低; 水稻叶片生理指标叶绿素含量（SPAD值）、 脯氨酸含量、 抗氧化酶系统活性则显著增加，表明外源Fe2+浓度100 mg/kg 是本研究条件下外源Fe2+ 对水稻生长产生显著毒害影响的临界点; 同时随外源Fe2+浓度的增加， 土壤微生物活性指标土壤微生物量碳、 微生物三大基础菌系总量（细菌、 真菌、 放线菌）、 功能菌系总量（氨化细菌、 固氮菌、 纤维分解菌）、 铁还原菌总量总体是先快速下降，后逐渐平稳降低。 半效应浓度EC50分析表明，外源Fe2+浓度100 mg/kg 为多数土壤微生物活性指标（微生物基础菌系总量、 功能菌系总量、 铁还原菌）EC50变化的临界值; 体系中土壤微生物活性指标和水稻生长指标的变化存在显著的相关性, 表明供试土壤亚铁对水稻生长的影响是亚铁对土壤-植物-土壤微生物系统同步影响的结果。综上结果可知，外源Fe2+浓度100 mg/kg为导致供试土壤中水稻生长及土壤微生物活性受到显著负效应的临界值，进而推知，本研究所用土壤对水稻生长和微生物活性的亚铁毒胁迫临界浓度约为300 mg/kg（含本底）， Fe2+含量超出该浓度时，需采取合理的农艺措施控制其负效应。
Abstract:In this study, the effect of exogenous ferrous (Fe2+) on the rice physiological indices, soil microbial activities and its bioecological characteristic at seedling and tillering stage in the interaction system between soil-rice-ferrous and microbe was investigated by a pot experiment in greenhouse, where the ferrous toxicity in waterlogged paddy soil was simulated. Ferrous with six different levels including 0, 100, 200, 400, 800 and 1600 mg/kg was applied respectively in paddy soil. The results showed that the addition of exogenous Fe2+ gradually inhibited the growth of rice and decreased the activities of soil microorganism, while the background concentration of Fe2 + in the normal tested paddy soil was 207.77 mg/kg. The plant height and dry matter accumulation of rice decreased significantly when the concentration of exogenous Fe2+ exceeded 100 mg/kg. However, SPAD value representing the content of chlorophyll in the leaf of rice, proline accumulation and activities of antioxidant enzyme systems increased obviously, suggesting that exogenous Fe2+ 100 mg/kg was the critical concentration leading to damage on growth in this experiment. Meanwhile, soil microbial activities declined rapidly and then steadily decreased with the increase of the concentration of exogenous Fe2+. The critical level in decreasing soil microbial activities can be presumed as 100 mg/kg of exogenous Fe2+ by analyzing its toxicant concentration that inhibits a microbe-mediated ecological process by 50% (EC50). Soil microbial activities and rice growth in the system of soil-rice-ferrous and microbe were significantly associated and synchronously affected by the ferrous in tested soil. Overall, exogenous Fe2+ of 100 mg/kg was the critical concentration in inhibiting rice growth and soil microbial activities in tested soil. Therefore, based on this result, the concentration of ferrous toxicity in tested paddy soil can be presumed as about 300 mg/kg, which includes the background level. Some reasonable agronomic measures should be considered in controlling the negative effects when the concentration of ferrous iron exceeds such concentration in the test paddy soil.
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