煤矸石山上不同种植年限和生长期香根草各部位全氮含量及其分配比例的比较

为了探明香根草〔Vetiveria zizanioides(Linn.)Nash〕在尾矿生态系统恢复中的作用机制,以贵州省六盘水市大河煤矿煤矸石山种植3、6、8和13 a的香根草为研究对象,分别在返青期、快速生长期、成熟期和枯黄期对香根草根、茎、叶和全株的全氮含量及其分配比例进行了比较.结果表明:在种植3、6、8和13 a,香根草根、茎、叶和全株的全氮含量均在快速生长期最高,并显著高于其余生长期.随种植年限增加,返青期、成熟期和枯黄期根的全氮含量,枯黄期茎的全氮含量以及返青期全株的全氮含量均逐渐升高;返青期茎和叶的全氮含量逐渐降低;快速生长期根的全氮含量,快速生长期和成熟期茎的全氮含量以及快速生长期、成熟期和枯黄期叶和全株的全氮含量先升高后降低,并在种植8 a最高.在种植6、8和13 a,快速生长期根的全氮含量分配比例最低,而快速生长期叶的全氮含量分配比例却最高.随种植年限增加,返青期根的全氮含量分配比例逐渐升高,而返青期茎和叶的全氮含量分配比例却逐渐降低;在种植8 a,快速生长期、成熟期和枯黄期根的全氮含量分配比例以及枯黄期茎的全氮含量分配比例最低或较低,而快速生长期和成熟期茎的全氮含量分配比例以及快速生长期、成熟期和枯黄期叶的全氮含量分配比例最高.在相同种植年限和生长期,香根草茎的全氮含量及其分配比例明显低于根和叶;总体来看,返青期、成熟期和枯黄期根的全氮含量及其分配比例高于叶,而快速生长期根的全氮含量及其分配比例却低于叶.研究结果显示:随着种植年限增加和生长期推移,香根草能够合理分配氮素资源,使其在煤矸石山立足,据此认为,香根草可用于煤矸石山的生态恢复和植被重建,但种植年限不宜超过8a.

Comparison on total nitrogen content and its allocation proportion in different parts of Vetiveria zizanioides in different planting years and growth stages on coal spoil-heaps

To figure out the action mechanism of Vetiveria zizanioides ( Linn.) Nash in ecological restoration of tailings, V. zizanioides planted on coal spoil-heaps of Dahe Coal Mine in Liupanshui City of Guizhou Province for 3, 6, 8, and 13 a were used as research objects, total nitrogen content and its allocation proportion in root, stem, leaf, and whole plant of V. zizanioides at returning green stage, rapid growth stage, mature stage, and withered yellow stage were compared. The results show that in planting for 3, 6, 8, and 13 a, total nitrogen content in root, stem, leaf, and whole plant of V. zizanioides is the highest at rapid growth stage, and is significantly higher than that at other growth stages. With increasing of planting year, total nitrogen content in root at returning green stage, mature stage, and withered yellow stage, that in stem at withered yellow stage, and that in whole plant at returning green stage all increase gradually;that in stem and leaf at returning green stage decreases gradually; while that in root at rapid growth stage, that in stem at rapid growth stage and mature stage, and that in leaf and whole plant at rapid growth stage, mature stage, and withered yellow stage increase firstly and then decrease, and are the highest in planting for 8 a. In planting for 6, 8, and 13 a, the allocation proportion of total nitrogen content in root at rapid growth stage is the lowest, while that in leaf at rapid growth stage is the highest. With increasing of planting year, the allocation proportion of total nitrogen content in root at returning green stage increases gradually, while that in stem and leaf at returning green stage decreases gradually. In planting for 8 a, the allocation proportion of total nitrogen content in root at rapid growth stage, mature stage, and withered yellow stage, and that in stem at withered yellow stage are the lowest or relatively low, while that in stem at rapid growth stage and mature stage, and that in leaf at rapid growth stage, mature stage, and withered yellow stage are the highest. In the same planting year and growth stage, total nitrogen content and its allocation proportion in stem of V. zizanioides are obviously lower than those in root and leaf. In general, total nitrogen content and its allocation proportion in root at returning green stage, mature stage, and withered yellow stage are higher than those in leaf, while those in root at rapid growth stage are lower than those in leaf. It is suggested that with increasing of planting year and prolonging of growth stage, V. zizanioides can reasonably allot nitrogen resource to adapt to coal spoil-heaps, accordingly, V. zizanioides can be used for ecological restoration and revegetation of coal spoil-heaps, but its planting year should not exceed 8 a.