Effects of Heat Shock to Seed Germination of Three Alien Plants

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.