假臭草植株不同分解阶段的化感作用动态变化

Dynamics of Eupatorium catarium Veldkamp allelopathy in the process of decay

以小白菜为生测对象,采用滤纸培养皿试验和盆栽试验研究了自然状态下假臭草植株分解过程中化感作用的变化动态。滤纸培养皿试验结果表明:假臭草植株提取液对小白菜种子发芽的抑制作用随浓度增大而增大,且随植株分解时间的延长而逐渐减弱;就幼苗根长而言,不同分解时期0.1g·mL-l的假臭草提取液对根长均表现为抑制作用,除未分解的假臭草以外,其他时期其他浓度的假臭草提取液对根系生长均有促进作用;假臭草提取液对小白菜茎长总体表现为促进作用。假臭草与土壤混合的盆栽试验显示,未分解的假臭草与土壤以50g·2kg-1比例混合对小白菜种子发芽有抑制作用,抑制率达68%,在土壤中分解10d后抑制作用消失;各时期假臭草对小白菜生物量均有显著提高作用。可见,假臭草作为绿肥具有较好的营养价值,但需依据其在不同生长时期对不同作物的化感作用强度和时间设置合理的施用量与施用方法。

The dynamics of Eupatorium catarium Veldkamp allelopathy was investigated under natural decomposition by bioassay of cabbage. The results of experiment with petri-dish filter paper method show that aquatic extracts from E. catarium that is naturally decomposed outdoors has an inhibitive effect on cabbage seed germination. While the inhibition effect increases with increase in extract concentration, it, however, decreases with decomposition time. With regards to the length of cabbage root, 0.1 g·mL^-1 aquatic extract of E. catarium inhibits root growth at every decomposition stage. With the exception of undecomposed E. catarium, other concentration extracts during decomposition enhances root growth. Aquatic extract from E. catarium also enhances cabbage stem growth. A pot experiment where 2 kg soil is mixed with 50 g E. catarium plant is used as a growth matrix for cabbage shows inhibi-tion on cabbage germination at the rate of 68%. However, after 10 days of decomposition, inhibition completely disappears. Cabbage biomass significantly increases when treated with E. catarium during its decomposing. The findings imply that E. catarium could be a vital source of nutrient for crops. But as green manure, fertilization amount and application method should be in accordance with E. catarium allelopathy intensity and duration at different growth stages of different crops.