摘要:通过测定横断山区干旱河谷18个川滇蔷薇种群新采集种子以及低温层积8周种子的发芽率和发芽速度，分析发芽率和发芽速度与种子特征以及环境因子之间的关系，阐明川滇蔷薇种子休眠与萌发的地理空间差异及其影响因素。结果表明，18个川滇蔷薇种群种子具有不同程度的休眠，新采集种子发芽率变化幅度大，为15.8%±5.0%至82.7%±2.3%，发芽速度指数范围：2.3%±0.2%至5.3%±0.5%。不同种群种子发芽率和发芽速度差异显著。新采集种子的发芽率在流域间存在显著差异，表现为金沙江流域 > 雅砻江流域 > 大渡河流域和岷江流域。新采集种子的发芽率和发芽速度随着采集地点海拔的升高而显著增加，即种子休眠程度随着海拔的升高呈现降低趋势。低温层积8周显著提高了种子发芽率和发芽速度，但减弱了种子发芽率和发芽速度在流域以及海拔间的差异。偏相关分析表明：瘦果皮厚度与新采集种子萌发速度成显著负相关关系；环境因子中年蒸发量与发芽率以及发芽速度之间关系最为密切，成极显著正相关关系；其次为年降水量，与发芽率和发芽速度之间具有显著的负相关关系。综合分析表明，川滇蔷薇种子休眠与萌发在横断山区干旱河谷存在较强地理空间差异。环境因子中年蒸发量和年降水量以及植物自身特征瘦果皮厚度是引起种子休眠与萌发地理空间差异的主要因素。



Abstract:Understanding the variation of seed germination characteristics of native species along geographic gradients is vital to develop restoration strategies for degraded lands. Rosa soulieana, a native shrub, has a great potential to rehabilitate the vegetation structure and function of the Hengduan mountain region. In order to understand the geographic variation of seed dormancy and germination of this native shrub, we selected 18 Rosa soulieana populations along the dry valleys of four rivers (Minjiang, Daduhe, Yalongjiang, and Jinshajiang) as plots. We recorded 7 environmental parameters: drainage, latitude, longitude, altitude, slope gradient, slope aspect, and height from the river in each plot. Five clumps in each plot were randomly selected for measuring the thickness of pericarp, achene mass and achene vitality. We measured germination parameters of freshly harvested achenes and cold-stratified achenes for 8 weeks of 18 R. soulieana populations. The relationship between germination index, seed characteristics and climatic factors in each plot was also analyzed. The results showed that seeds of all R. soulieana populations have a non-deep physiological dormancy. The germination percentages (GP) and the coefficient of rate of germination (CRG) of freshly harvested achenes varied significantly among 18 populations: from 15.8±5.0% to 82.7±2.3% for GP, and from 2.3±0.2% to 5.3±0.5% for CRG. The GP of freshly harvest seeds significantly differed among drainages. It was ranked as Jinsha drainage > Yalong drainage > Daduhe drainage and Minjiang drainage. The GP and CRG of freshly harvested seeds increased with the altitude of plot seeds collected, indicating a decrease of seed dormancy level with the altitude. Cold stratification of 5 ℃ for 8 weeks significantly improved the GP and CRG, and decreased differences of GP and CRG of seeds collected from different plots. The partial correlation analysis showed that the CRG was positively correlated with pericarp thickness. Annual evaporation was the most important climatic factor influencing germination, and it was positively correlated with the GP and CRG. Annual precipitation was negatively correlated with GP and CRG. The results of this study found an obviously geographic variation in seed dormancy and germination of R. soulieana in the dry valleys of Hengduan mountain region. Achene pericarp and climatic factors, such as annual evaporation and annual precipitation, contribute jointly to the geographic variation in seed dormancy and germination of this rose species.





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