摘要:选择青藏高原东南林线地区优势植物薄毛海绵杜鹃为对象，研究薄毛海绵杜鹃结实特性和萌发特性随海拔（4183-4673 m）、坡度、坡向等环境梯度的变化规律。对比了不同环境条件下薄毛海绵杜鹃果实的长、宽、重量、单果种子数、种子千粒重等结实特性；并测试了不同环境所产种子的萌发对温度和光照的响应。结果表明：（1）在高海拔低温胁迫环境下，薄毛海绵杜鹃的生殖投入加大，果实大且质量重，种子数量多但质量轻；（2）坡向是影响单果种子数量的主要环境因子，阴坡单果种子数显著大于阳坡，生活在阴坡的薄毛海绵杜鹃的繁衍能力更强；（3）较高和较低土壤湿度都会影响薄毛海绵杜鹃的种子质量，中等土壤湿度（28.3%-32.5%）薄毛海绵杜鹃种子萌发能力最强；（4）薄毛海绵杜鹃的种子是需光性种子，在黑暗条件下几乎不萌发；（5）在光照条件下，温度对种子萌发率和萌发速率有显著影响，高温（25/5℃）有助于提高萌发率并促使萌发进程显著提前。研究揭示了不同海拔薄毛海绵杜鹃结实和萌发特性与环境之间的关系，为薄毛海绵杜鹃的种质资源保护和气候变化背景下藏东南林线动态预测提供了基础资料。



Abstract:Fruiting and germination characteristics of the dominant plant species Rhododendron aganniphum var. schiaopeplum and their variation along the environmental gradients such as altitude (4183-4673 m), slope and aspect were studied at the alpine treeline ecotone on the southeastern Tibetan Plateau. The fruiting characteristics including fruit length, width, weight, seed number per capsule and 1000-seed weight of R. aganniphum var. schiaopeplum from different habitats were measured and compared, and the responses of seed germination to temperature and light were tested. The results showed that: (1) as cold-temperature stress increasing at higher altitude, the reproductive input of R. aganniphum var. schiaopeplum increased, with larger and heavier fruits, more seed number per capsule but smaller seeds than that from other environments; (2) slop aspect was the main factor affecting seed number per capsule with significantly larger seed number per fruit on the shady slope than that on the sunny slope, indicating a better reproductive ability on the shady slope; (3) seeds of the population in moderate soil moisture conditions (28.3%-32.5%) showed highest germination ability; (4) seeds of R. aganniphum var. schiaopeplum are photosensitive and cannot germinate in darkness; (5) in light conditions, germination percentage and rate are significantly affected by temperature, and the highest germination percentage and the most speedy germination showed at 25/5 ℃. This study investigated the relationship between fruiting and germination characteristics of R. aganniphum var. schiaopeplum and their habitat conditions, which provides basic data for the germplasm conservation and the dynamic prediction of the tree-line on the southeastern Tibetan Plateau in the context of climate change.





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