储藏和萌发温度对青藏高原东缘12种灌木种子萌发的影响

Effect of storage and temperature on seed germination of 12 shrub species from the eastern Qinghai-Tibet Plateau

研究了青藏高原东缘2个储藏条件下的12种灌木种子在10、15、20、25℃恒温培养下和5/25℃变温培养下的萌发特性及其与种子大小和生境的关系。结果表明:12种灌木室内干储种子在5/25℃变温培养下种子平均萌发率最高、萌发速率最快,室外埋藏种子10℃、5/25℃下种子平均萌发率相近且最高,但萌发速率5/25℃最快,10℃下最慢,4个恒温下的室内干储和室外埋藏种子的萌发速率均随温度升高而变快;10、15、20和25℃恒温培养下的室外埋藏种子平均萌发率、平均萌发速率均高于室内储藏,而5/25℃变温下则是室外埋藏种子平均萌发率、平均萌发速率均低于室内储藏;室内干储的12种灌木种子在5/25℃变温下的萌发率、萌发速率与种子大小呈显著负相关,而室外埋藏的种子在10℃以及5/25℃变温下的萌发率、萌发速率与种子大小均呈显著负相关,20℃下,只有萌发速率与种子大小呈显著负相关;其他储藏和温度下的萌发率、萌发速率与种子大小均没有显著相关;无论室内干储还是室外埋藏,阳坡灌丛物种在5个温度下的萌发率、萌发速率均显著高于阴坡灌丛物种,阴坡灌丛种子萌发率随温度升高而降低;变温有利于种子萌发,贮藏条件对种子的萌发特性的影响具有变温依赖性,种子的萌发特性与种子大小以及生境的关系具有明显的培养温度和储存条件依赖性。

Germination of 12 shrub species from eastern Qinghai-Tibet Plateau was tested at four constant temperatures （10, 15, 20, and 25 ℃） and one alternating temperature （5/25 ℃） under two storage conditions （outdoor burial and indoor dry storage）.The relationships between seed germination and storage condition, seed size and habitat were also tested. The results indicted that, the seeds stored indoors had the highest germination percentage and fastest germination rate at 5/25 ℃. The seeds buried outdoors had highest germination percentage at 10 ℃ and 5/25 ℃, the fastest germination rate at 5/25 ℃, the lowest germination rate at 10 ℃, and the lowest germination percentage at 25℃. The mean germination rate of the studied species was increased with increasing temperature. The germination percentage and germination rate of the seeds buried outdoors at 10, 15, 20, 25 ℃ were higher than those of the seeds stored indoors. However, an opposite result was found at 5/25 ℃. For the seeds stored indoors, there were significant negative correlations between germination percentage, germination rate and seed size at 5/25 ℃. For the seeds buried outdoors, there were significant negative correlations between germination percentage or rate and seed size at 10 ℃ and 5/25 ℃, and there also were significant negative correlations between germination rate and seed size at 20 ℃, but no relationships between germination percentage or rate and seed size at other temperatures. The seeds from the southern slope boscage had high germination percentages and germination rates at all the five temperatures regardless of storage condition, with the highest and lowest germination percentages observed at 5/25 and 15 ℃, respectively. The seeds from the northern slope boscage had the highest germination percentages at 5/25 ℃ regardless of storage condition, and the germination percentage decreased with the increase of temperature, regardless of storage condition. We concluded that temperature fluctuation benefited seed germination. The effect of storage condition on seed germination showed strong temperature dependence and the relationship between seed germination and seed size and habitat also varied with culture temperature and storage condition.