【作者】 刘信宝；

【导师】 沈益新； 张万均；

【作者基本信息】 南京农业大学 ， 动物营养与饲料科学， 2002， 硕士

【摘要】 白三叶(Trifolium repens L．)具有一定的抗逆性，能在轻度盐碱地上种植，并起到改良土壤的作用。加上它具备既美观又耐粗放管理的特点，在天津经济技术开发区绿化中发挥着重要作用。但是，由于白三叶生长茂盛，叶大株高，在天津经济技术开发区的气候条件下，存在美观度低、抗寒性差、冬枯早、返青晚，绿色期相对较短等问题。本研究针对天津经济技术开发区存在的问题，于2001年5月至2002年4月在天津经济技术开发区园林绿化公司实验地，分四个不同生长时期，对绿地白三叶进行叶面喷洒250、500、750、1000、1250ppm多效唑200ml／m~2的处理。探讨了了多效唑在白三叶矮化及绿色期延长上的作用机制及应用；并收集了国内绿化常用的白三叶品种进行了筛选比较，提出了适于该地区绿化使用的白三叶品种的建议。 多效唑处理对白三叶营养生长具有显著的抑制作用。处理后40天，白三叶的株高随处理浓度的提高而降低，叶片大小随处理浓度的提高而减小。多效唑处理后一周，白三叶叶色明显加深，叶绿素含量在较低浓度下随浓度的提高而增加，但当浓度过高(1000ppm以上)时，叶绿素含量反而有下降的趋势。施用多效唑过晚(11月中旬)，由于白三叶已基本停止生长，株高和叶片大小及叶色不表现出明显的变化；残效导致翌年白三叶返青和生长显著受抑。 多效唑处理使白三叶节间缩短，茎增粗，比叶重增加，提高了叶片和茎中可溶性糖及氮的含量，增强了茎与叶片对低温的抵抗力，显著降低白三叶经霜后的茎叶电解质渗出率(P＜0.01)，对白三叶冬前绿色期延长有一定的作用。但处理对翌年春季白三叶的返青没有明显的促进作用。 多效唑处理的浓度效应十分明显，白三叶矮化处理浓度以750ppm左右为宜，最大不应超过1000ppm。白三叶矮化处理不能过晚，应在白三叶生长旺季进行。否则，既起不到矮化作用，又对第二年返青及生长产生不良的影响。 目前绿化常用的白三叶品种海发、铺地、瑞文德及威亚四个品种在生长特性上存在着明显差异。海发株高及叶片较大，其余三个品种生长特性比较接近。瑞文德和铺地两品种苗期低温处理后，茎叶电解质渗出率和半致死温度显著低于海发和威亚。综合考虑生长特性和抗寒性能，瑞文德和铺地是相对适于天津开发区绿化带绿地的白三叶品种。更多还原

【Abstract】 The growth and cold resistance of white clover (Trifolium repens L.} treated with 250, 500, 750, 1000 and 1250ppm paclobutrazol solution at rate of 200ml/m2 were investigated in a field trail in Tianjin Economy and Development Area (TEDA) at four different times: May 23, June 20, Sep. 13 and Nov.12, 2001. The result showed that early three paclobutrazol treatments delayed the growth, and the Nov. 12, 2001 treatment had no significant effect because of low temperature.40 days after paclobutrazol treatments, the plant height of white clover reduced significantly with increasing paclobutrazol application rate. The length and the width of leaves reduced significantly. However, when the application rate reached 1000 ppm and above, the leaflets had unacceptable discoloration about three weeks. The Nov. 12, 2001 treatment had no obvious changes at the plant height and the leaflet size, but retarded the growth of white clover significantly the following year.The chlorophyll content of leaf increased with the application rate of paclobutrazol (under 1 000 ppm) increasing, and the chlorophyll content increased significantly by the treatment. When the application rate of paclobutrazol reached 1 000 ppm and above, the chlorophyll content of leaf reduced slightly. The Nov. 12. 2001 treatment had no significant effect on the chlorophyll content of leaf.The internode length reduced and the stem diameter increased by paclobutrazol treatments in the three early treatments. The content of soluble sugar and the nitrogen content of leaf and stem were increased in the three early treatments.The cold resistance of white clover treated with paclobutrazol at May 23, June 20. and Sep. 13. 2001 were improved, and the rate of electrolyte leakage of leaf and stem were reduced significantly after the first thick frost. But the regermination of white clover treaded by paclobutrazol was not improved or retarded significantly at the following year. The Nov. 12, 2001 treatment had no significantly effect on white clover’s cold resistance, and the treatment retarded the regermination of white clover significantly in the spring of 2002.The results showed that the paclobutrazol treatment had significant concentration effect and the concentration of paclobutrazol for growth regulation of white clover was suitable at 750ppm, no more than 1 000ppm. The paclobutrazol treatment should be processed at midseason of thegrowth of white clover; otherwise, the retarding effect was small and the regermination and growth of white clover in the 2nd year were retarded significantly.The results of the comparison of variety showed that Haifa > Riverdale, Persistent and Huia , the four varieties of white clover were differently in growth characteristics. The three other varieties’ leaf sizes were smaller than Haifa, and the heights were also lower. The rate of electrolyte leakage of stem and leaf and the LTso of Riverdale and Persistent were significantly lower than Haifa and Huia in seedling stage after low temperature treatment. Considering the growth characteristics and cold resistance, Riverdale and Persistent are the more suitable varieties to grow in TEDA green belt than the other two varieties.更多还原