【作者】 刘领；

【导师】 陈欣； 唐建军；

【作者基本信息】 浙江大学 ， 生态学， 2011， 博士

【摘要】 植物种间相互作用(竞争或互惠)的效应和机制是合理农作物间混套作系统建立的理论基础。大量研究表明,间混套作体系植物种间根系能够互补利用土壤养分资源,从而提高养分利用效率和提高作物总产量。但是,在土壤金属胁迫下植物种间相互作用的变化规律及其对间作作物重金属的吸收积累的影响,目前研究仍缺乏。本研究的科学假说是：“由于植物间相互作用产生的根际化学生态过程改变了植物共存的根际环境,从而影响植物共存条件下土壤重金属的生物有效性,进而影响植物对重金属离子的摄取”。本研究通过野外大田试验、盆栽试验、根系分隔试验进行探索。取得了以下结果：1土壤重金属复合污染条件下作物及其种间相互类型对重金属的响应特征作物对土壤重金属的摄取与作物及金属离子的类型有关。对于铅,两个叶用型的作物(包菜和小青菜)的可食部分的铅含量高于两个果实型的作物(玉米和番茄)；对于镉,番茄和小青菜的可食部分的镉含量较高；对于铜,玉米和小青菜的可食部分铜含量较高。种间相互作用下作物类型对土壤不同重金属的响应特征是不同的。对于铅,玉米、包菜和小青菜在间作的条件下倾向于减少作物体内不同部位的铅含量；而番茄却相反,番茄在间作的条件下各部位的铅含量却有增高的趋势。对于镉,所有作物在间作的条件下各部位的镉含量均有所提高,尤其是当作物与豆科植物鸡眼草间作时,各部位的镉含量相比于作物单种显著增加。对于铜,玉米间作番茄处理各部位的铜含量明显的高于玉米单种,而番茄、包菜、小青菜各部位的铜含量没有受种植方式显著影响。2种间相互作用下玉米与烟草不同基因型对土壤镉污染的响应特征相比于各自的单种处理,豆科植物鸡眼草共存条件玉米和烟草不同基因型各部位的镉含量、每盆镉的提取量、镉的生物富集因子显著提高,但镉的生物转移因子没有显著的变化。3种间相互作用下的根际环境及土壤镉的生物有效性种间相互作用影响了作物共存条件下的根际环境及土壤镉的生物有效性。相比于单种,玉米共存鸡眼草与烟草共存鸡眼草土壤pH均显著降低；豆科植物鸡眼草共存条件下作物玉米和烟草的菌根真菌侵染率均有所提高,尤其是两个烟草基因型,在Cd3水平下,烟草两个基因型(K326和云烟-87)的菌根真菌侵染率分别比各自的单种处理提高了21%和15%；与单种相比,豆科植物共存条件下土壤可交换态的镉含量明显增加。4根系分隔条件下的种间根际效应分析种间根际不同互作方式显著地影响了玉米和烟草各部位的镉含量及每盆镉的总提取量。在玉米与鸡眼草互作时,导致共存条件下镉提取量增加的原因主要由根系效应决定的,其次是溶液效应,再次是菌根效应；而且随着土壤镉含量的增加,菌根效应的权重明显降低,而根系效应和溶液效应的权重有所增加。在烟草与鸡眼草互作时,导致共存条件下镉提取量增加的原因也主要是由根系效应决定的,其次是菌根效应,再次是溶液效应；而且随着土壤镉含量的增加,根系效应的权重显著降低,而菌根效应和溶液效应的权重有所增加。5重金属胁迫条件下的种间关系土壤重金属复合污染或单一镉污染条件下,间作豆科植物鸡眼草时,玉米、番茄、烟草的生物量或产量显著提高,玉米与番茄间作时,玉米是间作优势植物,生物量及产量提高,番茄生物量及产量降低。包菜、小青菜在本试验的间作模式下生物量及产量没有显著变化。随着土壤镉含量的增加,共存条件下玉米不同基因型的生物量先增加后减小,烟草不同基因型的生物量逐渐增加,伴生植物鸡眼草的生物量无显著变化,表明在轻度土壤重金属镉污染条件下植物种间的竞争与互补机制增强了共存条件下不同功能群植物对土壤重金属的偏利性。6重金属污染条件下作物安全生产评价及种间相互作用的应用依据我国食品中重金属污染物的限量标准,在试验的重金属复合污染的农田中进行番茄、包菜、小青菜三种作物生产均存在重金属铅、镉污染风险；仅玉米(在所有的种植方式下)可食部分铅、镉、铜的含量均低于限量标准,可用于安全生产,但考虑到间作促进玉米镉的吸收积累,建议单种。玉米不同基因型可食部分镉含量差异显著。依据镉污染限量标准,在轻度镉污染的土壤上(<1mg/kg土壤),郑单-958和申甜-1两个玉米基因型可以安全生产；而在镉含量高于1mg/kg的土壤上所有的玉米基因型均存在安全风险；考虑到玉米申甜-1基因型较郑单-958基因型具有更高的镉提取量,因此玉米(申甜-1)在轻度镉污染的土壤(<1mg/kg土壤)上具有边生产边修复的潜力。烟草K326基因型生物量高,且其生物富集因子和转移因子均大于1,尤其与豆科植物鸡眼草共存时镉提取量较大,具有镉污染土壤生物净化提取的潜力。更多还原

【Abstract】 Interspecific interactions between plants (competition or facilitation) are the theoretical basis of establishment of intercropping or mixed cropping system. It is well documented that complementary use of soil nutrients between intercropped plants has greatly increased efficienct of nutrient utilization, and thus enhanced total yields. Under the soil with heavy metal contamination, however, whether and how intercropped plants affect bioavailable of metal in soil, and thus affect metal uptake by plants have not been well studied. Here I hypothesize that plant interactions may altered the rhizospheric environment, and further change the bioavailability of metal and affect metal uptake by plants. I conducted both field and greenhouse experiments to test these hypotheses. The results obtained in these experiments are as follows:1The responses of crop to soil contaminated with heavy metal under interspecific interactionsMetal accumulating in edible parts of crops varied with types of metals and crops. Pb concentration was higher in edible parts of leafy vegetables (cabbage and pakchoi), Cd concentration was higher in edible parts of tomato and pakchoi, and Cu was higher in edible parts of maize and pakchoi.Crop co-planting tended to decrease in Pb accumulation and increase in Cd accumulation, especially, when co-planted with Japanese clover, Pb in edible parts of maize, cabbage and pakchoi were much lower, and Cd in edible parts of tomato and pakchoi were obviously higher relative to they grown alone, respectively. Cu in edible parts of maize was higher when co-planted with tomato than when maize monoculture, but Cu concentrations were not significantly affected by planting patterns in tomato, cabbage and pakchoi.2The responses of maize and tobacco different genotypes to soil contaminated with cadmium under interspecific interactionsCompared to monoculture, for each genotype of maize or tobacco, Cd concentration, Cd uptake and Cd bio-concentration factor were significantly higher when co-planted with Japanese clover, but Cd transfer factor had no significant difference.3Rhizosphere environment and Cd bioavailability of soil under plants interspecific interactionsRhizosphere environment and Cd bioavailability in soil were significantly affected by plant patterns. Compared to monoculture, for each genotype of maize or tobacco, the colonization rates of arbuscular mycorrhizal fungi were higher when co-planted with Japanense clover, especially, for two tobacco genotype, the colonization rates of arbuscular mycorrhizal fungi of tobacco (K326) and tobacco (Yunyan-87) in Cd3treatment were increased by21%and15%, respectively. Compared to monoculture, soil pH was significantly lower and soil exchangeable Cd concentration was significantly higher when crop co-planted with Japanese cover.4The different rhizosphere effects in root barrier experimentCd concentrations and Cd uptake of maize and tobacco were significantly affected by different root barrier treatments. When maize co-planted with Japanese clover, the increment of Cd uptake in co-planted system was mainly determined by root effect, followed by solution effect, and finally by mycorrhizal effect. With soil Cd elevated, mycorrhizal effect decreased, and root effect and solution effect increased. When tobacco co-planted with Japanese clover, the increment of Cd uptake in co-planted system was also mainly determined by root effect, followed by mycorrhizal effect, and finally solution effect. With soil Cd elevated, root effect decreased, and mycorrhizal effect and solution effect increased.5Interspecific relationships of crops under heavy metal stressUnder soil contaminated with several heavy metals or single cadmium, compared to monoculture, the biomass or yield of maize, tomato and tobacco significantly increased when co-planted with Japanese cover. In maize and tomato intercropping system, maize was the dominant crop, biomass or yield increased when compared to maize alone. The biomass or yield of cabbage and pakchoi were not significantly affected by plant patterns in our experiment. With soil Cd elevated, the biomass of different maize genotypes first increased and then decreased, and biomass of different tobacco genotypes was gradually increased, and the co-planted plant, Japanense clover, was not significantly affected in biomass. This indicated that the mechanisms of competition and facilitation of plant interspecies enhanced the preferences of different functional group plants to Cd in mildly Cd-contaminated soil.6The safety production assessment of crops and the application of plant interspecific interations under soil contaminated with heavy metalAccording to the maximum permissible concentration (MPC) standard of the National Standard Agency in China, the edible parts of tomato, cabbage and pakchoi had potential risk of Pb or Cd pollution, only maize (under all planting patterns) can be safely consumed. Considering the Cd concentration of maize edible part can be enhance by intercropping, especially, co-planting with Japanese clover of legume, the results suggest that maize monoculture is the optimum crop planting pattern grown in soil contaminated by electronic wastes.Cd concentrations in edible parts had significant difference among maize different genotypes. According to the MPC standard, the edible parts of Zhengdan-958and Shentian-1were safe in mildly Cd-contaminated soil (<1mg/kg), and all maize genotypes had Cd pollution risks when soil Cd concentration is more than lmg/kg. Considering Shentian-1had higher Cd uptake than Zhengdan-958, the results suggest that Shentian-1has the potential for satety production and phytoremediation when soil Cd concentration is less than lmg/kg.Tobacco (K326) had high biomass under soil Cd stress, and both bio-concentration factor and transfer factor of Cd are more than1, especially, when co-planted with Japanese clover, K326had substantial quantities of Cd uptake. The results suggest that tobacco (K326) has the potential for phytoextraction when soil contaminated with cadmium.更多还原