【作者】 刘明美；

【导师】 沈益新；

【作者基本信息】 南京农业大学 ， 动物营养与饲料科学， 2004， 硕士

【摘要】 随着土壤重金属污染的日益严重和可耕地面积的逐年减少，重金属污染土壤的开发利用越来越受到人们的关注。利用牧草适应性广、生长快、产量高的特点，在重金属污染不太严重的土壤上种植，能够产生很好的经济效益、社会效益和生态效益。 多花黑麦草（Lolium multiflorum L．）品质优良，抗性好，是饲草生产和草坪绿化中常用的禾本科牧草。本实验以多花黑麦草品种特高（Tetragold）为材料，采用砂培和土培两种栽培方式，在其分蘖初期分别以系列浓度的Cu²⁺和Pb²⁺溶液进行处理，研究了Cu²⁺和Pb²⁺递进胁迫下多花黑麦草的萌发、分蘖期的生长以及植株的营养成分的变异。 结果表明：本实验设置的浓度范围内，Cu²⁺和Pb²⁺处理对牧草的萌发影响不大。低浓度Cu²⁺和Pb²⁺处理下，多花黑麦草种子的萌发和幼芽的生长受到明显的促进，出现增效效应。随着Cu²⁺和Pb²⁺处理浓度的升高，种子发芽率、芽长、根长和生物量迅速下降，幼苗生长受到显著抑制。同一处理浓度下，Cu²⁺和Pb²⁺处理对种子根、芽和发芽率的抑制率存在明显的差异：根＞芽＞发芽率。Cu²⁺对多花黑麦草种子发芽及幼苗生长的影响远远大于Pb²⁺的影响。 砂培和土培的研究结果表明，低浓度的Cu²⁺和Pb²⁺处理对多花黑麦草的生长无不利影响，其株高、单株叶面积、地上部生物量等出现增效效应。随Cu²⁺和Pb²⁺处理浓度的升高，多花黑麦草的株高、单株叶面积、分蘖数、单株干物质重、根系重等迅速下降，植株生长受到严重抑制。而且Pb²⁺比Cu²⁺表现出了更强的抑制效应；同一Cu²⁺和Pb²⁺处理浓度下，多花黑麦草根系生长的受抑程度远大于地上部生长。砂培条件下对多花黑麦草生长表现为抑制作用的浓度，土壤条件下则表现为明显的刺激作用。显示出土壤对Cu²⁺和Pb²⁺污染有很强的缓冲作用。 低浓度的Cu²⁺和Pb²⁺处理下，多花黑麦草茎叶CP含量较对照有所增加，高于对照。随着Cu²⁺和Pb²⁺处理浓度的升高，茎叶CP含量迅速降低。植株地上部NDF含量随Cu²⁺处理浓度升高而升高；Pb²⁺处理下，NDF含量在土培和砂培两种种植方式间出现不同的变化趋势：砂培时NDF含量先降后升，土培时先升后降。相同Cu²⁺和Pb²⁺处理浓度下，土壤对多花黑麦草品质的降低有很强的缓冲作用；Cu²⁺对多花黑麦草品cuZ十和PbZ‘胁迫对多花黑麦草生长及饲草品质的影响质降低的效应大于Pb2+的效应。 cu2+和Pb2+的处理浓度不同，多花黑麦草体内cu2+和Pb2+的积累量不同。随着cu2+和Pb2+处理浓度的升高，多花黑麦草茎、叶、根各器官中的cu2+和PbZ十积累量急剧增加。相同的cuZ十或Pb2+处理浓度下，cu2+和Pb2+积累在植株体内的分布存在明显的器官差异性，根>>茎>叶，根部的cu2+或Pb2+含量远远高于茎和叶中的含量。多花黑麦草吸收的cu2+和Pb2+主要累积在植株根部，向地上部运输的很少。 综合cu2+和Pb2+胁迫下多花黑麦草的生长效应、饲草品质变化以及牧草茎叶中c矿+和Pb2+的蓄积量，可以推测，土壤溶液中cu2+浓度15一30mg/L或<5 omg/kg（土壤）和Pb2+浓度<20omg/L或<500mg瓜g（土壤）为多花黑麦草用于畜教业生产的临界值。 另外，cu2+浓度<700mg/kg（土壤）和Pb2+浓度<2 o00mg/kg（土壤）的地区种植多花黑麦草，植株体cu2+和 Pb2+的积累量虽然已远远超过家畜生产规定的标准，但较草的生长状况良好且产量高于对照。因此在此污染土壤上种植多花黑麦草，既可一美化环境，又可通过收获牧草带走土壤中的Pb2+，不失为一条改良与利用重金属污染土壤的可行之路。更多还原

【Abstract】 With increasing heavy metal pollution and decreasing arable farmland, more attentions to the utilization of polluted soil have been paid. Forage grasses have wild adaptability and high yielding characteristics, which can grown on the heavy metal polluted soil.Italian ryegrass (Lolium multiftor-um L.) is a famous species used in forage production and turf establishment. In this experiment, Italian ryegrass (cv. Tetragold) was treated by Cu2+ or Pb2+ solutions with different concentrations in tillering period. Response of seed germination, plant growth and nutrition components was studied in pot experiments.The results showed that seed germination was not delayed obviously and that seeds germination rate and seedlings growth were promoted by low Cu2+ and Pb2+ concentration treatment. Compared with the control, with increasing Cu2+ and Pb2+ concentration, seed germination rater length of bud and seed root, dry weight of bud and seed root were decreased rapidly. In addition, the inhibition of Cu2+ treatment to germination rate, bud and seed root growth was stronger than that of Pb2+ treatment. At the same Cu2+ or Pb2+ concentration, the inhibition to root growth was more significantly than to bud growth and seed germination.Growth of young plants was promoted by low Cu2+ or Pb2+ concentrations. With increasing Cu 2+ and Pb2+ concentrations, plant height, tiller number, leaf area per plant, chlorophyll content in leaf and the dry weight of above ground part and root decreased rapidly. Growth was seriously inhibited under high Cu2+ or Pb2+ concentration.Compared with the control, forage quality of Italian ryegrass was not affected heavily under low Cu2+ and Pb2+ concentration. Crude protein (CP) in the stem and leaf increased and neutral detergent fiber (NDF) decreased or affected little. But with increasing Cu2+ or Pb2+ concentration, the NDF content was increased andtotal CP yield of plant was decreased rapidly. Forage quality was dropped significantly.Accumulation of Cu2+ or Pb2+ in root, stem and leaf increased with increasing the treatment concentrations. In the same stress concentration, Cu2+ or Pb2+ content in. root was obviously greater than that of stem and leaf. Cu2+ and Pb2+ were absorbed and attributed in root largely, few were transported to the above ground part.Concerning to the growth, the forage quality and the Cu2+ and Pb2+ accumulation in stem and leaf of Italian ryegrass, it is possible to grow Italian ryegrass for forage production on the soil , which Cu2+and Pb2+ concentration were not higher than 15-30mg/L( or 50mg/kg soil) and 200mg/L (or 500mg/kg soil), respectivelyDuring the experiment, It was also found that Italian ryegrass grew well on the polluted soil, with the concentration of Cu2+ 500 mg/kg (soil) and Pb2+^ 2000m g/kg( soil). So planting and reaping Italian ryegrass on polluted soil is a good method to relive the heavy metal pollution of soil更多还原