贵州省烤烟产区2年连作制度下土壤杂草种子库变化特征

Change Characteristics of Soil Weed Seed Bank in Tobacco Two-years Continuous Cropping System in Guizhou Province

为明确贵州当前烤烟种植制度下烟田土壤杂草种子库的特征与变化趋势,预测田间杂草发生、消长及演替规律,指导烟田杂草综合防控,采用直接萌发法,对贵州不同生态区域烟田土壤杂草种子库进行研究。结果表明:在2年连作烤烟田,土壤杂草的种子库密度和物种数均呈下降趋势,其中,种子库密度下降明显,降比达34.03%。对于单个物种而言,马唐和辣子草等优势杂草的种子密度相对稳定,通泉草和藜等杂草的种子密度呈上升趋势。相同区域同一种植制度下,田间杂草管理措施是干扰杂草种子库变化的主要原因,且烟田杂草种子库密度垂直分布相对保持一致,对各土层杂草种子密度分布的影响不大。各地区土壤杂草出苗主要以第一次萌发为主,前2次土壤杂草种子萌发占杂草萌发数量的96%以上。贵州烟田田间杂草防控的关键时期在5月下旬至6月上旬。

The soil weed seed bank composition in tobacco fields of different biological area was investigated and studied by using the seedling germination method to make clear the change characteristics and trend of soil weed seed bank for prediction of weeds occurrence,dynamics and succession as well as guidance of integrated weeds management in tobacco field. The results showed that two-years tobacco continuous cropping had decreasing effect on soil weed seed bank species density and diversity,and the proportion of species density declined by 34. 03%. To single weed population,some weeds density keep relatively stable,like Digitaria sanguinalis,Conyza canadensis,et al. Whereas,other weeds,such as Mazus japonicus,Centella asiatica,seed density showed an increasing trend. Weed management was the leading cause to the change of weed seed bank in the same cropping system of the same region. And comparison of the same cropping system in the same area showed a relatively uniform vertical distribution of the weed seed bank density,and tobacco continuous cropping had little influence on the distribution of weed seed density in different soil depth. The emergence period of soil weed seed focused on the first germination mainly,and the number of the first two germination accounted for more than 96 % of the total soil weed seed germination. So late May to early June is a critical period for weed prevention and control in Guizhou tobacco fields.