荞麦和金荞麦根际土壤铝形态变化及对其生长的影响

Forms of Aluminum in Rhizosphere Soil and Its Effect on Growth of Fagopyrum esculentum and Fagopyrum cymosum

不同形态的铝对不同植物的毒害不同。以荞麦和金荞麦为实验材料,设置4个不同的土壤铝处理浓度（0,0.1,0.2,0.4 g Al^3＋/kg）,研究荞麦和金荞麦根际土壤中铝形态变化及对其生长的影响。结果表明,当土壤铝处理浓度〈0.2 g/kg时,尽管根际土壤液中铝溶出量较对照组有明显上升,毒性大的交换态铝和单聚体羟基铝（称为活性铝）占可提取铝总量的比例增加,但荞麦和金荞麦茎伸长和水分利用增强,地上部分生物积累量增多,表明荞麦和金荞麦对低铝胁迫有一定的适应;当土壤铝处理浓度达到0.4 g/kg时,荞麦和金荞麦根际土壤pH降至最低,根际土壤液中铝的溶出量增至最高,严重抑制了荞麦和金荞麦叶片光合作用的正常进行,各项指标和对照差异达到显著水平,荞麦和金荞麦的生长表现出明显的铝毒害症状。因此,我们推断在根际土壤活性铝溶出量为0.106-0.143 m g/g和0.046-0.057 m g/g间可能分别存在着荞麦和金荞麦耐受铝毒害的某个阈值。

Different forms of Aluminum （Al） have different harm intensities to different plants, so the study of vegetal responses of plants to different forms of Al stress is of great significance. In this research, Fagopyrum esculenturn （buckwheat） and Fagopyrurn cyrnosurn （gold buckwheat） were cultured in soil to studied the various forms of Al in the their rhizosphere soil and the effect of the forms on plant growth, under four different Al treatment concentrations （0, 0. 1, 0. 2, 0. 4 g Al^3＋/kg）. The result revealed that when acid-aluminum concentration was less than 0. 2 g/kg, buckwheat and gold buckwheat had higher shoot length, shoot weight and water utilization efficiency （WUE）, indicating they adapted this condition at a certain extent. When acid-aluminum treatment reached 0. 4 g/kg, it was found that the photosynthesis of buckwheat and gold buckwheat were greatly inhibited, the obvious aluminum toxic symptom as plant rhizosphere soil pH values decreased to the least, while the amount of different aluminum forms extracted from plant rhizosphere soil solutions increased to the most. Combining with those conclusions, it can be inferred that the threshold of actived Al toxicity in the rhizosphere soil on buckwheat was between 0. 106-0. 143 mg/g, while that on gold buckwheat was between 0. 046 - 0. 057 mg/g.