- 作者: Albrecht JUNGK
- 作者服務機構: Georg August University Institute of Agricultural Chemistry
- 中文摘要: 本文之主要目的在摘述植物吸收磷酸時其根部與土壤間交互作用之特質,並就影響植物磷肥供應之因子提供量化資料,引用實例係參卓作者研究群之研究工作。 植物礦物營養之供給為兩種複合現象之交互作用結果:即土壤中之有效性與植物之吸收作用;此有效性一辭概述影響植物營養供給之土壤因子,其主要取決於土壞中營養之濃度與移動性,至於吸收作用則描述與植物營養供給有關之植物因子,主要取決因子為根系之大小及其構成單員之吸收效率。於礦物營養進入活體之部位-土壤與根部界面,此些交互作用尤其重要。 根與土壤中營養一開始之接觸係由兩種機制促成:(I)由根生長到達土壤中營養存在之位置,及(Ⅱ)土壤中營養向根部之移動。就由根生長達到接觸作用而言,根之形態特徵及其於土壤中之分佈相當重要;根越細且根長度與密度越高,其對營養之截取效果也越好,基於此,根系之大小與形態等變數皆為重要因子;營養於土壤中之傳送,主要取決於影響土壤溶液中營養成分濃度、緩衝能力與擴散作用等之土壤特性,因此土壤中擴散性流動之量化敘述很重要,濃度梯度為其決定因子,梯度之形成主要由於營養之吸收降低根表土壤溶液中之濃度,其既可導致由土壤到根之淨擴散作用,又可導致營養由固態土壤釋出至溶液中,根系營養吸收之動力學也因此而為其根本重要因子。 本文之重點在討論磷,縱然植物於磷的吸收極有效率,自然界土壤中磷的有效性,卻是經常太低而無法足夠植物之需要。除上述對所有營養供給皆然的根本機制以外,植物本能上已知可分泌某些根圈物質,其能提高土壤中磷的溶解度,此些物質舉其要者有質子與重碳酸根離子、梭基以及磷酸分解酵素等,又者,許多植物根系在有特定菌根菌的共生時,較之無此些真菌共生之根系能更有效率的由土壤中吸收磷。
- 英文摘要: The aim of this article is to summarize knowledge on the nature of interactions between root and soilwhen plants absorb phosphate and to present quantitative information on the factors affecting phosphorussupply of plants. Examples are based on work of the author's research group. Mineral nutrient supply of plants is the result of interactions between two complex phenomena:availability in soil and acquisition by plants. The term availability summarizes the soil factors affectingnutrient supply of plants. It is a function of concentration and mobility of the nutrient in soil. Acquisitiondescribes the plant factors involved in nutrient supply of plants. It is a function of the size of a root systemand the uptake efficiency per unit of root. These interactions are particularly important at the soil-rootinterface, the site of entry of mineral nutrients into the living system. As the first step contact between roots and the nutrients in soil is brought about by two mechanisms:(i) growth of roots in soil to the sites where the nutrient is located and (ii) movement of the nutrient throughthe soil toward the root. To achieve contact by root growth the morphological properties of roots andtheir distribution in soil are important. The thinner the roots and the higher root length density the bettercan nutrients be intercepted. For this reason parameters of the size and of morphological root propertiesare important. Transport of nutrients through the soil depends on the soil properties affecting nutrientconcentration in the soil solution, buffer power and diffusion. For this reason a quantitative descriptionof the diffusive flux in soil is important. It depends on concentration gradients. These are created byuptake of the nutrient which decreases soil solution concentration at the root surface. It causes both net-diffusion from the soil toward the root and release of the nutrient from the solid soil phase into solution.For this reason the kinetics of nutrient uptake of the root system is of basic importance. In this article only phosphorus (P) will be regarded. Even though plants are very efficient in collectingP, phosphorus availability in natural soils if often too low to provide adequate P supply of plants. Inaddition to the mechanisms mentioned above, which are fundamental for all nutrients, plants have de-veloped the ability to exude substances into the rhizosphere which increase the solubility of soil P. Amongthese protons and bicarbonates, carboxylates and phosphatases are known to be important. Furthermore,the symbiosis of roots with mycorrhizal fungi are effective in many plant species to collect phosphate fromsoil more efficiently than plant roots without these fungi.
- 中文關鍵字: phosphorus dynamics in the rhizosphere; phosphorus diffusion in soil; plant phosphorus supply; plant phosphorus uptake kinetics.
- 英文關鍵字: --