覆膜对伴矿景天生长和吸镉动态影响研究

为探讨覆膜对伴矿景天生长和吸镉动态影响,以湖南某休耕地试验区为供试农田,研究了镉锌超积累植物伴矿景天在垄上覆膜和未覆膜两种栽培条件下,移栽后不同时间的植物生物量、地上部镉浓度变化与吸取修复动态。结果表明:伴矿景天的单株鲜质量和干质量在移栽后157～214 d范围内增速最快。覆膜和未覆膜处理的单株鲜质量增速分别为3.92 g·d~(-1)和3.25 g·d~(-1),单株干质量增速则分别为0.23 g·d~(-1)和0.17 g·d~(-1)。随着生长时间的延长,伴矿景天地上部镉浓度呈先降低后升高再降低的变化趋势;而吸镉量则因生物量的增加而呈现逐渐增大的趋势,其中在30～63 d范围内的日平均吸镉量较高(覆膜和未覆膜处理分别为3.62 g·hm~(-2)·d~(-1)和3.10 g·hm~(-2)·d~(-1)),最小值为移栽初期的0～30 d(覆膜和未覆膜处理分别为0.90 g·hm~(-2)·d~(-1)和0.26 g·hm-2·d~(-1))和生育后期的214～240 d(覆膜和未覆膜处理分别为0.20 g·hm~(-2)·d~(-1)和0.25 g·hm-2·d~(-1))。覆膜和未覆膜处理下,伴矿景天的镉总吸收量分别为447.00 g·hm~(-2)和329.85 g·hm~(-2);供试田块0～20 cm土层土壤镉去除率分别为16.18%和12.16%。研究表明,相对于未覆膜处理,覆膜能显著提高伴矿景天地上部生物量、镉吸收量及对污染土壤中镉的吸取修复效率。

Effect of film mulching on plant growth and cadmium uptake by Sedum plumbizincicola

In order to determine the effect of plastic film mulching on the growth and Cd uptake of Sedum plumbizincicola, which is a Cd and Zn hyperaccumulator, a fallow field located in Hunan Province was selected, S. plumbizincicola plant seedlings were transplanted, the dynamics of plant biomass and shoot Cd concentration after transplanting were determined during all growth stages, and the amount of Cd uptake was calculated. The results showed that the single-plant fresh and dry weight of S. plumbizincicola increased very quickly during 157~214 days after transplanting (the increase rates of fresh weight of each plant for the film mulching and no film mulching treatment were 3.92 g·d^-1 and 3.25 g·d^-1, respectively; the increase rates of dry weight were 0.23 g·d^-1 and 0.17 g·d^-1, respectively). With the increase in growth time, shoot Cd concentration decreased at the early stage, increased gradually, and then decreased again at the last growth stage. However, the Cd uptake amount increased at all stages. The effect of mulching on average daily Cd uptake was the greatest during the range of 30~63 days, which was 3.62 g·hm^-2·d^-1 and 3.10 g·hm^-2·d^-1 for the film mulching and no film mulching field treatment, respectively. The two lowest average daily Cd uptake stages were in the range of 0~30 days (0.90 g·hm^-2·d^-1 and 0.26 g·hm^-2·d^-1, respectively) and 214~240 days (0.20 g·hm^-2·d^-1 and 0.25 g·hm^-2·d^-1, respectively). Under the film mulching and no film mulching field treatment, the total Cd uptake by S. plumbizincicola was 447.00 g·hm^-2 and 329.85 g·hm^-2, respectively, and the soil Cd removal rate was 16.18% and 12.16%, respectively. In general, compared with the no film mulching field treatment, film mulching significantly increase plant biomass, Cd uptake, and the soil Cd removal rate by S. plumbizincicola.