水杉凋落物水浸提液对其种子萌发和生长的化感作用

Allelopathy of aqueous extract from Metasequoia glyptostroboides litter on its seed germination and growth

关键词:  水杉, 凋落物, 天然更新, 化感作用, 自毒作用, 水浸提

Key words:  Metasequoia glyptostroboides, litter, natural regeneration, allelopathy, autotoxicity, aqueous extract

摘要:

为探究水杉凋落物的化感作用是否是影响其天然更新的障碍因素,该文设置了8种水杉新鲜凋落物和自然凋落物水浸提液浓度200、100、50、20、10、5、2、1 g·L^-1和CK,分析不同类型不同浓度凋落物水浸提液对水杉种子萌发和生长的化感作用的影响。结果表明:(1)水杉新鲜凋落物水浸提液对水杉种子发芽率和发芽势影响不显著(P>0.05),对发芽指数有显著影响(P<0.05),1、100、200 g·L^-1显著抑制种子发芽; 水杉自然凋落物水浸提液对水杉种子萌发3个指标影响均不显著(P>0.05),而浓度为5、10、50、200 g·L^-1时则有抑制效应。(2)水杉种子芽长、胚轴和主根长度均在不同浓度的新鲜和自然水杉凋落物水浸提液间差异显著(P<0.05),并随着水浸提液浓度的增加(≥10 g·L^-1)而逐渐降低,尤其是50～200 g·L^-1范围内抑制作用显著增强。(3)新鲜和自然水杉凋落物水浸提液对自身种子萌发后生长的抑制作用相较于对种子萌发强,并且新鲜凋落物的化感效应抑制强度大于自然凋落物。(4)在种子萌发和生长指标中,主根长度对化感物质反应最敏感。(5)水杉种子的芽长生长动态变化符合“S”型生长曲线(R2≥0.988)。总之,水杉凋落物对自身种子萌发和生长具有一定的化感抑制效应,影响其种群天然更新,建议在水杉种群管理中,适当清理林下凋落物,以促进水杉种群的天然更新。

Abstract:

To explore whether the allelopathy of Metasequoia glyptostroboides litter is an obstacle to its natural regeneration, eight concentrations(200, 100, 50, 20, 10, 5, 2, 1 g·L^-1 and CK)of aqueous extracts from fresh and natural litter of M. glyptostroboides were set to analyze the allelopathic effects of aqueous extracts of different types and concentrations on seed germination and growth of M. glyptostroboides. The results were as follows:(1)The aqueous extract of the fresh M. glyptostroboides litter had no significant effects on seed germination rate and germination energy(P>0.05), but had significant effects on germination index(P<0.05), and seed germination was significantly inhibited by 1, 100, 200 g·L^-1 treatments. The effects of aqueous extracts of the natural M. glyptostroboides litter on three indexes of seed germination were not significant(P>0.05), but the inhibitory effect was reflected in 5, 10, 50, 200 g·L^-1.(2)The shoot length, hypocotyl length and main root length of M. glyptostroboides seeds were significantly different between different concentrations of fresh and natural litter aqueous extracts(P<0.05), and decreased gradually with the increase of aqueous extract concentrations(≥10 g·L^-1), especially in the range from 50 to 200 g·L^-1.(3)Compared with seed germination, the aqueous extracts of fresh and natural M. glyptostroboides litters had stronger inhibitory effect on the growth of seeds after germination, and the allelopathic effect of fresh litter was stronger than that of natural litter.(4)The main root length was the most sensitive to allelochemicals among seeds germination and growth indexes.(5)The dynamic change of shoot length growth of M. glyptostroboides seeds accords with the “S” type growth curve(R2≥0.988). In summary, the litter of M. glyptostroboides has a certain allelopathic inhibitory effect on its own seed germination and growth, which affects the natural regeneration of its population. It is suggested that the litter under the forest should be properly cleaned to promote the natural renewal of the M. glyptostroboides population in the management of M. glyptostroboides populations.