湿地植物通气组织和渗氧对其重金属吸收和耐性研究进展

湿地植物具有强大的通气组织和根部渗氧能力特征,使得其根际微环境处于氧化状态从而适应湿地土壤浸水的环境。近年来,湿地植物通气组织和渗氧在重金属吸收和耐性研究方面已引起了人们的关注,并对此进行了相关的研究。本文分别对湿地植物通气组织和渗氧特征,通气组织和渗氧对重金属吸收和耐性影响、对根际微环境影响等方面的研究进展和存在问题进行了综述,并提出了该领域未来可能的研究方向。认为针对从通气组织和渗氧角度出发研究湿地植物重金属耐性机理,应重点对湿地植物根际重金属的环境化学行为展开深入研究,在研究方法和手段上应注重新技术的开发与应用。     

Genetic regulation of root traits for soil flooding tolerance in genus Zea

Flooding stress caused by excessive precipitation and poor drainage threatens upland crop production and food sustainability, so new upland crop cultivars are needed with greater tolerance to soil flooding (waterlogging). So far, however, there have been no reports of highly flooding-tolerant upland crop cultivars, including maize, because of the lack of flooding-tolerant germplasm and the presence of a large number of traits affecting flooding tolerance. To achieve the goal of breeding flooding-tolerant maize cultivars by overcoming these difficulties, we chose highly flooding-tolerant teosinte germplasm. These flooding-tolerance-related traits were separately assessed by establishing a method for the accurate evaluation of each one, followed by performing quantitative trait locus (QTL) analyses for each trait using maize × teosinte mapping populations, developing introgression lines (ILs) or near-isogenic lines (NILs) containing QTLs and pyramiding useful traits. We have identified QTLs for flooding-tolerance-related root traits, including the capacity to form aerenchyma, formation of radial oxygen loss barriers, tolerance to flooded reducing soil conditions, flooding-induced adventitious root formation and shallow root angle. In addition, we have developed several ILs and NILs with flooding-tolerance-related QTLs and are currently developing pyramided lines. These lines should be valuable for practical maize breeding programs focused on flooding tolerance.     

籼粳杂交稻高效吸收氮素的相关机理研究

通过盆栽和水培实验研究了籼粳杂交稻甬优12（YY-12）、嘉优中科6（JY-6）和常规粳稻秀水134（XS-134）常规供氮（M-N）和低氮（L-N）下分蘖盛期水稻氮素利用效率差异，并初步探讨相关机理机制。结果表明：YY-12和JY-6在两种供氮水平下氮素吸收效率明显大于XS-134。与XS-134相比，YY-12和JY-6根系干物质累积明显增大，加之根孔隙度（POR）较大，使其根系径向泌氧量（ROL）明显增加。从而很可能造成YY-12和JY-6根际土壤氨氧化菌（AOB）数量和硝化强度明显增加；使YY-12和JY-6根际土壤矿质氮含量明显大于XS134。相关分析表明根际土壤矿质氮含量与水稻氮素吸收效率极显著正相关。因此，YY-12和JY-6氮素吸收效率高很可能与其种植使根际土壤硝化强度增加和有机氮矿化加剧紧密相关。另外，与M-N处理相比，YY-12和YY-6氮素吸收效率在L-N水平下明显增加，而XS-134无明显差异。主要原因为：与M-N相比，YY-12和YY-6在L-N水平下根系干物质累积和POR增加比例均大于XS-134；ROL和根际土壤硝化强度，以及根际土壤矿质氮含量下降比例小于XS-134。     

凤眼莲根系分泌氧和有机碳规律及其对水体氮转化影响的研究

通过模拟实验,研究凤眼莲不同苗龄根系分泌氧及有机碳的规律,在此基础上分析凤眼莲根系分泌氧和有机碳对富营养化水体溶解氧、有机碳及无机氮(NH+4和NO-3)转化的影响。研究结果表明凤眼莲根系具有较强的泌氧及分泌有机碳的能力,小、中、大三个苗龄凤眼莲根系泌氧速率分别达56.19、93.15、106.32μmolO2·h-1,根系分泌有机碳的速率分别达0.25、0.60、0.92 mg·L-1·h-1。不同苗龄凤眼莲根系泌氧及有机碳的速率随苗龄的增加显著升高,而其相对应的单位根系泌氧和有机碳的能力随苗龄的增加呈降低趋势。水体中无机氮的去除率随着凤眼莲苗龄的增加而增加,这除了与凤眼莲的吸收作用有关外,还因为其泌氧和分泌有机碳的总量增加加强了硝化和硝化-反硝化过程的潜力,从而高效并快速地净化水体中外源氮负荷。