【作者】 罗献宝；

【导师】 白厚义； 何勇强； 黎晓峰；

【作者基本信息】 广西大学 ， 植物营养学， 2003， 硕士

【摘要】 苜蓿（Medicago sativa L.）是适应于中性土壤上生长的豆科牧草作物，为了解酸性土对苜蓿生长的影响，本研究通过不同试验方法探索了酸、铝对苜蓿初生根伸长的效应。研究结果表明： 1．苜蓿初生根对酸、铝作用高度敏感，酸、铝作用对苜蓿初生根的伸长构成胁迫。 2．低pH对苜蓿初生根可产生不可逆性的伤害，pH4.1处理6h可导致初生根根尖“死亡”；酸害所产生的主要症状是根尖弯曲及根尖组织“白化”。 3．铝对苜蓿初生根胁迫的主要症状是根尖弯曲、肿胀、根尖颜色褐化及根尖粘液分泌减少：在pH 4.5条件下，3 μmol.L^-1铝处理8h对苜蓿初生根伸长的抑制率超过50％。 4．自分解试验表明，酸、铝均可抑制苜蓿初生根根尖胞壁的自分解反应。 5．钙不仅能够有效缓解酸、铝对苜蓿初生根的毒害作用，还可以部分或全部消除酸、铝对根尖胞壁自分解反应的抑制作用。 研究结果表明，酸、铝对苜蓿初生根胁迫作用的表现存有不同程度的异同处，二者对苜蓿初生根的伸长均可独立地产生抑制作用。本研究所确定的酸害及铝毒对供试苜蓿初生根的胁迫作用的具体指标及钙对酸、铝胁迫作用的影响可为探究苜蓿根的酸、铝胁迫提供深入研究的基础。更多还原

【Abstract】 In this study, the effects of acidity and/or aluminum(Al) on alfalfa primary root were investigated by different ways of experiment, the result indicates that alfalfa primary root is high sensitive to acidity and Al, and both acidity and Al are stress factors to elongation of alfalfa primary root. In low-pH medium, alfalfa primary roots would suffer an irreversible damage and lost viability within 6 h exposure to pH 4.1 medium containing 0.5 mmoI.L-1 Ca. The major symptoms developed by low-pH includes curvature and etiolation in root apical. In contrast to low-pH stress, The symptoms by Al induces curvature, turgor and changing color to brown in root apical, and results in a thinner mucilage secreted from root tip. At pH4.5, elongation of alfalfa primary root exposed to 3mol.L-1 Al for 8 h was inhibited by more than 50%. Experiment using cell wall of alfalfa primary root tip showed that both low-pH and Al could inhibit cell wall autolytic activity. Additional calcium could not only alleviate stress on primary root induced by acidity and Al effectively, but also alleviate the inhibition of cell wall autolysis resulted from acidity (partly) and Al(fully).更多还原