植物-土壤的交互作用:腐殖质的作用

Soil-root Cross-talking:The Role of Humic Substances

近40年来,腐殖质(HS)的生物活性已得到了重点关注和研究。HS的生长促进作用已在实验室和大田的一些植物中得到证实。其中形态发生效应的研究包括在完整植株中诱导侧根形成和根毛的起始,以及在处理过的细胞愈伤组织中刺激根和地上部的发育。HS通过诱导碳、氮循环和次生代谢,提高养分利用效率,促进大量、微量元素的同化,促进植物生长。本综述主要论述内容包括:(1)植物与土壤HS的作用机制。(2)植物对HS刺激效应的响应、植物应对HS的调节回路以及植物群落结构之间的反馈。(3)基于近期关于碱法提取土壤HS的争论,讨论植物从土壤中获得生物活性物质的能力。这些讨论结果表明,植物能够改善土壤,创造和维持有利于植物生长和生存的成长环境。因此,根分泌出的有机物质并不是碳和能量的浪费和损失,而是植物与土壤交互作用而互促发展的典型代表。土壤或HS主体中生物活性的有机/HS物质的活化流通对植物和土壤健康至关重要。

The biological activity of humic substances(HS)has been elucidated in the last 40 years.Growth enhancement from HS has been demonstrated in several plants in the laboratory and the field.Morphogenesis effects have also been investigated and include induction of lateral root formation and root hair initiation in intact plants and stimulation of root and shoot development in treated cell calluses.HS enhance nutrient use efficiency,aiding assimilation of both macro and microelements and promoting plant growth by the induction of carbon,nitrogen,and secondary metabolism.The review aims are to:(1)shed light on the mechanism by which plants“talk”with soil through humic substances,(2)elucidate the plant responses to the stimulatory effects of HS,the regulatory circuits that allow plants to cope with humus,and the feedback between plant community structures,and(3)show(in light of recent debate about the alkaline extraction of soil humic substances)the plant capability to acquire biologically active substances from soil.It will be shown that plants modify soils,creating and maintaining favorable habitats for growth and survival.Therefore,organic substances exuded by roots are not a wasteful loss of carbon and energy.They represent an evolved strategy by which plants‘‘talk’’to the soil.The mobilization of bioactive organic/humic substances from bulk soil or bulk humus is critical to plant and soil health.