不同温度下PEG模拟干旱对濒危植物狭叶坡垒种子萌发的影响

Effects of simulated drought by PEG-6000 on thegermination of Hopea chinensis seeds underdifferent temperature conditions

狭叶坡垒(Hopea chinensis)种子为典型的顽拗性种子。为探究种子萌发对温度和水分的适应性,该研究在人工气候培养箱内设置3种温度(15、20、25℃),采用6个聚乙二醇(PEG-6000)浓度(0%、5%、10%、15%、25%和35%)模拟干旱胁迫处理,研究狭叶坡垒种子的萌发特性。结果表明:(1)温度对种子萌发具有显著影响。同一干旱胁迫浓度下,种子的萌发率、萌发势、萌发指数、胚根长、芽长和活力指数随着温度升高呈上升趋势,萌发时滞随温度升高而降低,萌发历期随温度升高而波动性上升。(2)干旱胁迫对种子萌发具有显著影响。同一温度下,种子的萌发率、萌发势、萌发指数、萌发历期、胚根长、胚芽长和活力指数随着干旱胁迫程度加重呈降低的趋势,萌发时滞随干旱胁迫程度加重而升高。(3)温度和干旱胁迫的交互作用对种子萌发具有显著影响。干旱胁迫下,不同温度条件下种子萌发的表现不同。在35%PEG-6000胁迫下,20℃和25℃时,种子萌发率分别为8.89%和15.55%,显著高于15℃(0%)。综上所述,适宜种子萌发的温度为20℃和25℃,适宜幼苗早期生长最佳温度为25℃;干旱程度越大,种子萌发受到的抑制作用越强,干旱胁迫对种子萌发的影响高于温度因素,适当增温可缓解干旱胁迫对种子萌发的抑制作用。

Hopea chinensis is distributed in China and its seeds are typically reclacitrant.In order to investigate the germination adaptability of seeds to temperature and moisture,we carried out an experiment with three different constant temperatures(15,20,25℃)controlled by artificial climate incubators,and used six polyethylene glycol(PEG-6000)concentrations(0%,5%,10%,15%,25%and 35%)to simulate drought stress.The germination characteristics of these seeds were carefully examined.The results were as follows:(1)Temperature exerted a significant influence on seed germination.Regardless of the level of drought stress applied,higher temperatures positively affected the germination percentage,germination energy,germination index,radicle length,sprout length and vitality index of seeds,higher temperatures led to shorter germination delay and increased fluctuations in the germination duration.(2)Drought stress had a significant impact on seed germination.Under identical temperature conditions,increasing levels of drought stress resulted in decreasing of germination percentage,germination energy,germination index,germination duration,radicle length,sprout length and vitality index of seeds.Moreover,higher levels of drought stress led to longer germination delay of seeds.(3)The interaction between temperature and drought stress had a significant influence on seed germination.Under drought stress,seed germination exhibited different responses under different temperature conditions.Specifically,under conditions where a PEG-6000 concentration of 35%was applied as drought stress treatment,the germination percentage at temperatures of 20℃and 25℃were significantly higher than those observed at 15℃(8.89%and 15.55%compared to lower percentage at 15℃).However,it was important to note that when subjected to both 35%PEG-6000 and a temperature of 15℃,the seeds no longer germinate.In summary,our results indicate that the suitable temperatures for seed germination are identified as being at 20℃and 25℃.It is determined that the most favorable temperature for early seedling growth is 25℃.As the drought stress intensifies,the inhibitory effect on seed germination become stronger,the effect of drought stress on seed germination is higher than that of temperature.Additionally,moderate warming can help alleviate the inhibitory effect of drought stress on seed germination.