Element Recycling Activity during a Life Cycle of a Plant.

植物在其生命周期中一直在将环境的营养变化融入其生长过程中。因此，从元素回收系统的角度出发，植物中的元素动力学有望为我们评价或保护环境提供有用的信息。作者首先研究了巴西半干旱区主要树种卡廷格林的土壤和根系以及根到植物上部的元素分配情况。在此基础上，分析了牵牛花生命周期中元素形态的变化动力学。在植物的每个组织中，都有按生命周期形成的各种元素梯度，其模式在生长的幼期和成年期都没有改变。在牵牛花的例子中，大多数过渡元素没有被运送到发育中的种子中。特别是Mn在生长过程中积累到老叶中，作为养分返回土壤，供下一代生长。Al， V和Na的大部分没有被输送到植物的上部，因此，在下一代中，这些元素似乎仍然有足够的数量。在被调查的元素中，K似乎是使下一代生长的限制因素。茎叶钾离子浓度始终高于叶片钾离子浓度，表明叶片的渗透压受到调控。如果不向土壤补充钾，3代之内缺钾土壤可能会抑制植株的生长。在caatinger灌木的情况下，一些物种的Ca或Mg等二价元素往往被消耗殆尽。因此，在调查地区，应选择不大量吸收二价元素的树种，以保护土壤免受植物养分减少的影响。

Plant has been integrating the environmental nutritional change into its growth during the life-cycle. Therefore, the element kinetics in a plant is expected to provide a useful information for us to evaluate or protect the environment, from the point of element recycling system. The authors, first of all, had investigated how the elements are partitioned between soil and root, as well as root to the upper part of the plant in caatinger woods, which are the main wood species covering the semi-arid area in Brazil. Then the author analyzed the kinetics of element profile pattern during life-cycle of the plant, morning-glory. In every tissue of the plant, there has been each element gradient formed according to the life cycle and the pattern did not change during juvenile or adult phase of the growth. in the case of morning-glory, most of the transition elements were not transported to the developing seeds. Especially, Mn were accumulated to the old leaf during the growth and was, therefore, returned to the soil as a nutrient to grow the next generation. Most of Al, V and Na were not transported to the upper part of the plant, therefore, in the next generation, there still seems to remain a sufficient amount of these elements. Among the elements investigated, K seemed to be a restricting element to render the next generation grow. Potassium concentration in the leaf stem was always kept higher than that of the leaf, suggesting the regulation of a osmotic pressure of the leaf If additional K was not supplied to the soil, in three generations, K deficient soil might inhibit the plant growth. In the case of caatinger bush, divalent element, such as Ca or Mg tended to be used up in some species. Therefore, in the area investigated, the wood species, which does not uptake divalent element in a large amount should be selectively used to preserve the soil from the decrease of the plant nutrient.