喀斯特地区珍贵树种黄枝油杉的种子萌发特性

Seed germination characteristics of Keteleeria calcarea, a precious tree species in karst area

关键词:  黄枝油杉, 种子, 形态, 萌发, 贮藏

Key words:  Keteleeria calcarea, seed, morphology, germination, storage

摘要:

黄枝油杉为中亚热带喀斯特地区珍贵树种,该物种分布范围狭窄,野生种群幼苗数量少,严重限制了其自然更新。为探求该物种濒危的原因,同时为其保护和利用提供参考,该文对黄枝油杉的种实性状进行了测定,并研究了温度、光照、土壤含水量、基质、贮藏温度和时间、不同地理种源等因素对种子萌发的影响。结果表明:(1)黄枝油杉球果平均结种率为7.45%±6.54%,种子有较长种翅[(2.27±0.32)cm],种子平均长度为(1.55±0.15)cm(不含种翅),平均宽度为(0.62±0.05)cm,平均厚度为(0.46±0.04)cm,平均千粒重为(214.81±14.76)g,风干种子平均含水量为15.28%±1.66%。(2)黄枝油杉种子萌发的适宜温度为25 ℃,在20 ℃和30 ℃下萌发率显著降低(P<0.05); 种子萌发不需要光照,但周期性光照条件下的萌发率显著高于持续光照和持续黑暗条件(P<0.05); 种子在土壤含水量为10%～30%条件下均能萌发,且能耐一定程度的干旱; 适宜萌发基质为质地疏松、透气性好的泥炭土和珍珠岩; 种子不耐贮藏,采集后应及时播种; 3个不同地理种源中以桂林恭城县三江乡种群种子萌发率最高。黄枝油杉球果结种率较低,种子萌发对温度要求严格,且种子易失去活力,这可能与其濒危有很大关系。

Abstract:

Keteleeria calcarea is a precious tree species in the mid-subtropical karst area, this species has a narrow distribution range and very few seedlings in wild populations, which severely limits the natural renewal of the population. In order to explore the causes for the endangerment of this species and provide reference for its protection and utilization, the cones and seeds morphological characteristics of K. calcarea were measured, and the effects of temperatures, light conditions, soil water contents, substrates, storage temperatures and time, and different geographical provenances on seed germination were studied. The results were as follows:(1)The average seed setting rate of K. calcarea cone was 7.45%±6.54%, the seed wing length was(2.27±0.32)cm, the average seed length was(1.55±0.15)cm(excluding seed wing), the average width was(0.62±0.05)cm, the average thickness was(0.46±0.04)cm, and the average 1 000-seed weight was(214.81±14.76)g, the average water content of dried seeds was 15.28%±1.66%.(2)The optimum temperature for seed germination was 25 ℃, and the germination rate decreased significantly at 20 ℃ and 30 ℃(P<0.05); Seed germination did not need light, but the germination rate under periodic light was significantly higher than that under continuous light and continuous darkness(P<0.05); The seeds could germinate under the conditions of 10%-30% soil water contents, and could withstand a certain degree of drought; Peat soil and perlite with loose texture and good air permeability were suitable for germination; The seeds were not resistant to storage and should be sown in time after collection; The seed germination rate of Sanjiang population in Gongcheng County of Guilin was the highest among the three geographical provenances. The seed setting rate of K. calcarea cone was low, the seed germination was strict with temperature, and the seed was easy to lose vigor, which may be an important reason for its endangerment.