东南景天玉米轮作体系中黑网或黑膜覆盖对植物生长和镉锌含量的影响

通过小区试验对比黑网覆盖、黑膜覆盖以及空白对照的杂草控制率、作物产量以及重金属镉锌含量,衡量覆盖黑网控草的效果。结果表明:在东南景天小区试验中覆盖黑网对杂草的控制率3次分别为93.08%、93.12%、77.99%,覆盖黑膜对杂草的控制率3次分别为100%、98.39%、87.39%,两种控草方法均对杂草具有较好的控制效果;低Cd玉米小区试验的结果与之相似。与空白相比,覆盖黑网能显著增加东南景天产量、Cd含量和提取率;覆盖黑网的玉米小区追施喇叭口肥后地表径流营养元素(N、P、K)浓度低于覆盖黑膜,与对照相当。因此,覆盖黑网能够实现有效控制杂草,且施用化肥时可以不用掀开,适合在Cd污染土壤上应用。

Effect of black-net or black-film coverage on plant growth and Cd and Zn contents in Sedum alfredii and corn rotation

The effects of black-net coverage, black-film coverage, and control(CK), i.e., without coverage, on weed control were studied in order to reduce the labor cost. Weed control rate, crop yield, and Cd and Zn contents of crops were measured. Field experiments were conducted with Cd-contaminated soil. Results showed that, for Sedum alfredii Hance plantings in field plots, the rates of weed control by blacknet coverage were 93.08%, 93.12%, and 77.99% for three harvest times of weeds after cropping, whereas those by black-film coverage were 100%, 98.39%, and 87.39%, meaning both methods controlled the weeds well. In the second experiment, with low-Cd corn plantings, the results obtained were rather similar. Compared to CK, black-net coverage increased the yield of S. alfredii, Cd content in plants, and total Cd phytoextraction. The nutrient(nitrogen, phosphorus, and potassium) concentrations in runoff water following additional chemical fertilization after the corn flowering with the treatment of black-net coverage were lower than those of black-film coverage and similar to those of CK. Hence, black-net coverage could not only effectively control weeds, but also had advantages of permeating the rainwater through the nets and no need for opening the nets during chemical fertilization. This method is particularly suitable for application in phytoremediation of Cd-contaminated soils.