典型湿地植物与湿地农田作物铁含量的季节变化特征

Seasonal variation of iron content in typical wetland plants and in wetland farmland crops in Sanjiang Plain of Northeast China

分析了三江平原自然湿地的优势种小叶章（Calamagrostis angustifolia）、乌拉苔草（Carex meyeriana）、毛苔草（C．lasiocarpa）和湿地农田中的大豆（Giycine max）和水稻（Oryza sativa）各器官铁含量的季节变化特征。结果表明：3种湿地植物各器官的铁含量呈金字塔构型，成熟期（9月）时位于金字塔尖的叶的铁含量约为位于塔底的下草根层（地下20～30cm）的3．08％、4．42％和1．18％；幼龄期（5月）的铁含量垂直剖面Logistic拟合很好，R^2分别达1．0000、0．9902和0．9954；整个生长季地下部分铁含量均逐渐降低，而地上部分具有种间和器官间差异。相比之下，农作物大豆和水稻的铁库主要集中在地下根系中，且随生长季的延长而逐渐富集；地上部分的铁含量远低于根系，其中地上部分又以叶的含铁量最高，随生长期的延长有所增加，平均增长率分别为5．67％和75．61％；成熟期作为种子的大豆和稻米铁含量最低，仅相当于同期根铁含量的5．50％和0．44％。不同物种间相同器官铁含量的差异随生长期不同而变化。湿地植物对土壤铁的富集能力要大于湿地农田作物。

This paper studied the seasonal variation of iron content in different organs of Calamagrostis angustifolia, Carex meyeriana, and C. lasiocarpa, the dominant plant species on the natural wetland of Sanjiang Plain, and of soybean （ Giycine max） and rice （ Oryza sativa） , the main crops planted on the wetland farmland of the Plain. In late growth season （September） , the iron content in C. angustifolia, C. meyeriana, and C. lasiocarpa all presented a pyramid form, with the leaf iron content at the top of pyramid being 3.08%, 4.42%, and 1.18% of the sod layer （20-30 cm） iron content at the bottom of pyramid, respectively; while in early growth season （May）, the profile of iron content fitted Logistic model well （R^2 = 1. 000, 0. 9902, and 0. 9954, respectively）. In the whole growth season, the iron content in the underground part of test wetland plants decreased gradually, while that in aboveground part changed with species and organs. By contrast with that of wetland plants, the iron pool of wetland farmland crops was mainly in roots, and increased with time during the growth season. The iron content in the aboveground part of the crops was far lower than that in crop roots, and in the aboveground part, leaf had the highest iron content. During growth season, the mean increasing rate of leaf iron content was higher for rice （75.61%） than for soybean （5.67%）. At maturing stage, the iron content in the grains of soybean and rice was the lowest, only being 5.50% and 0.44% of that in roots. The iron content in the same organs of different plant species varied with growth stage, and the iron accumulation of wetland plants was more significant than that of wetland farmland crops.