摘要
对柑橘根系Ca2+吸收的通量分析表明：根系对Ca2+吸收表现出明显的"难进易出"的特点，由细胞质进入环境的单向速率常数Kco大大高于由环境进入细胞质的单向速率常数Koc；根系吸收Ca2+时内流较小，但外流却相对较大，进入细胞质的绝大部分Ca2+又外流到环境中；根系各区域中Ca2+分布为自由空间＞液泡＞细胞质，根系吸收Ca2+的净内流（Joc）很小，上运速率更小，因此根系吸收的Ca2+只有很小一部分上运到地上部。此外，还根据自由空间中较高的Ca2+含量和钙难被再利用的特点对Ca2+的通量分析方法进行了初步改进。
The compartmental analysismethod for Ca2+ was improved according to the high Ca2+ content in freespace and its reuse ability in citrus (Citrus unshiu Mare. ) root, The resultsshowed a high efflux rate and a low influx rate of citrus root for Ca2+ uptake.The unidirectional rate constant of Ca2+from cytoplasm to environment (Kco )was much higher than that (Koc) in theopposite direction (table 2). Most of theCa2+ enter the cytoplasm soon return tothe envitonment. It was found that thedistribution of Ca2+ in citrus root is inthe following order: free space (33. 135μmol/L) Mvacuole (2 0. 157 μmol/L ) >cytoplasm (1. 029 μmol/L) (table 1).The net influx (J. of Ca2+ into the citrus root was very low (0. 097 μmol g-1FW h-1). The upward transport ratewas even lower (0. 015 μmol g-1 FWh-1 ), which was only 15. 46 % of theinflux, indicating that only a tinyamount of the Ca2+absorbed by the rootwas transported to the upper parts of theplant.
关键词
柑橘
钙
吸收
运输
通量分析
citrus, calcium, uptake, transport, fluxanalysis
