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热激对3种外来植物种子萌发的影响

Effects of Heat Shock to Seed Germination of Three Alien Plants

  • 摘要: 为探究森林可燃物燃烧释放的热量对土壤种子库种子的影响,以我国常见的外来植物银荆、黑荆、银合欢为研究对象,在室内模拟不同温度土壤为传热介质,对种子进行干热激处理后进行萌发试验,计算种子萌发率、萌发速率指数,分析热激温度和热激时间对种子休眠、萌发及萌发速率的影响。结果表明:3种外来植物种子均具有一定的耐高温性,由大到小为:银荆种子 > 银合欢种子 > 黑荆种子。恒温土壤条件下打破银荆、黑荆和银合欢种子休眠的最低温度及热激时间分别为:60 ℃ × 7 min、60 ℃ × 3 min、60 ℃ × 3 min;最适萌发温度范围分别为:80~100、70~90、70~90 ℃,其平均萌发率为40%~60%。方差分析表明,热激温度比热激时间更重要,最适萌发温度内延长热激时间种子萌发率在一定范围内波动。热激温度70~110 ℃对种子萌发均有显著促进作用,140 ℃ × 30 s时种子几乎完全丧失萌发力。

     

    Abstract: The heat released by the combustion of forest fuel heats the soil, which has an important impact on the number, viability, and dormancy of seeds in the soil seed bank, and then affects the natural regeneration of plant populations in the burned area. In order to explore the effect of heat released by forest fuel combustion on the seeds of soil seed bank, the common alien plants Acacia dealbata, A. mearnsii and Leucaena leucocephala in China were taken as the research objects, and the soil with different temperatures was simulated as the heat transfer medium, and the germination test was carried out after dry heat shock treatment on the seeds, and the seed germination rate and germination rate index were calculated, and the effects of heat shock temperature and heat shock time on seed dormancy, germination and germination rate were analyzed. The results show: 1) The seeds of the three alien plants all had certain high temperature resistance, from large to small: Acacia dealbata seeds > Leucaena leucocephala seeds > A. mearnsii seeds. 2) The minimum temperature and heat shock time to break the dormancy of the seeds of Acacia dealbata, A. mearnsii and Leucaena leucocephala under constant temperature soil conditions were 60 ℃ × 7 min, 60 ℃ × 3 min and 60 ℃ × 3 min, respectively. The optimal germination temperature ranges were 80~100, 70~90 and 70~90 ℃, and the average germination rate was 40~60%. 3) The analysis of variance showed that the heat shock temperature was more important than the heat shock time, and the seed germination rate fluctuated within a certain range within the optimal germination temperature. 4) The heat shock temperature between 70~110 ℃, had a significant effect on seed germination, and the seeds almost completely lost their germination ability at 140 ℃ × 30 s. The results of this study can lay the foundation for the development of the planned burning formula for the natural regeneration forests of Acacia dealbata, A. mearnsii and Leucaena leucocephala, and provide a scientific basis for the development of technologies to control the invasion of the three alien plants by fire.

     

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