Analysis of Mechanisms in the Interaction Between Aluminum and Silica in Plant and Soil System.

(1)由于硅铝形成难溶沉淀物，易溶SiO_2含量通常较高的Allophanic Andosol具有铝含量低的特点。(2)这一现象很好地反映在流经土壤主要形成区的河水中的含硅量。(3)在酸性土壤中加入2 mm的二氧化硅，可减轻铝对植物的伤害。(4)二氧化硅缓解铝毒害的机制主要是通过在根尖周围积累大量的二氧化硅，防止铝与根尖细胞表面接触。因此，根的排铝功能变得更强。(5)在高酸性土壤中生长良好的野牡丹需要铝才能正常生长，施硅对其生长无明显促进作用。这种现象可能是由于氧化铝…过高所致。生长介质中二氧化硅的存在降低了铝的吸收率。(6)由链霉菌(Streptmyces Scabies)引起的马铃薯赤霉病严重制约了全世界优质马铃薯的生产，目前还没有建立起防治马铃薯赤霉病的有效方法。然而，研究表明，铝浓度比抑制马铃薯生长的浓度低，对链霉菌的生长有抑制作用。马铃薯赤霉病既有传导性土壤，也有抑制性土壤，但其原因尚不清楚。本研究发现，马铃薯赤霉病在土壤溶液中硅含量较高的氨基安多酚等土壤中容易发生，从而导致铝浓度较低。相反，在硅含量较低的土壤上，马铃薯赤霉病的发病率较低，从而导致铝浓度较高。结果表明，前者为导电性土，后者为抑制性土。(7)在高硅导电土上种植马铃薯时，采用行施氮肥、表施磷钾肥的施肥方法，可有效抑制马铃薯黑星病的发生。通过采用上述施肥方法，由于土层中的离子强度较低，块茎生长层周围土壤溶液中的铝保持了较高的活性。较少

(1) Allophanic Andosols, in which soluble silica content was usually high, had a characteristics with a low aluminum concentration, as silica and aluminum formed difficultly soluble precipitation. (2) This phenomena was well reflected to the silca concentration in the river water flowing through the areas where the soils were formed mainly by allophanic Andosols. (3) Growth injury in plants caused by aluminum in acid soils was alleviated by the coexistence of 2 mM silica in the growth media. (4) Mechanisms of the effect of silica on the alleviation of aluminum toxicity was mainly to prevent contact of aluminum on cell surface of roots by the accumulation of a large amount of silica around the root tips. As a result, the aluminum-excluding function of the roots became higher. (5) Melastoma malabathricum grown well in the highly acidic soils required aluminum for the normal growth and the growth was not stimulated by the silica application. This phenomena might be caused by the high alum … More inum requirement of this plant and the decrease of aluminum absorption by the coexistence of silica in the growth media. (6) Potato common scab disease induced by Streptmyces scabies is a serious constraint in the production of potato with good quality in the whole world, as the good method to prevent the occurrence of this disease has not been established. However, it was clarified that growth of Streptmyces scabies was inhibited by a lower concentration of aluminum than that inhibiting potato growth. It has been known that there are conductive soils and suppressive soils for potato scab, but the reason was unknown so far. In this study, it was found that potato common scab occurred easily in the soils such as allophanic Andosols which had a high concentration of silica in the soil solution, thus making aluminum concentration lower. On the contrary, occurrence of potato common scab was low in the soils which had a low concentration of silica, thus making aluminum concentration higher. It was demonstrated that the former was the conductice soil and the latter the suppressive soil. (7) When potato was grown in the conductive soils with a high silica concentration, it was indicated that application of aluminum sulfate together with a fertilizing method, in which nitrogen fertilizer was applied on the row and phosphate and potassium fertilizers are supplied on the soil surface, was effective for suppressing the potato common scab. By employing the fertilizing method described above, a high activity of aluminum in the soil solution around the tuber growing horizon was maintained due to the lower ionic strength in the horizon. Less