高寒草地瑞香狼毒的开花物候特征及花寿命

Flowering phenology characteristics and floral longevity of Stellera chamaejasme in alpine grasslands

以祁连山东缘高寒草地瑞香狼毒(Stellera chamaejasme)自然种群为研究对象,测量了不同水平(种群、个体和花序)的开花物候和花寿命,探究了瑞香狼毒开花物候特征和花寿命的进化意义。结果表明:1)该种植物在6月中下旬-7月下旬开花,其种群、个体和花序水平的花期分别为35、18.97和9.80 d。2)种群在个体和花序水平上的开花同步指数分别为0.86和0.78,均只有一个开花高峰。3)单花和花序水平的花寿命与始花期之间均呈极显著负相关关系(P<0.001)。4)花序不同位置小花的花寿命之间存在显著差异(P<0.01),边缘花的花寿命最长,中部花次之,顶部花的花寿命最短。总体表明,瑞香狼毒属于“集中开花模式”,花寿命随开花期以及花着生位置的显著变化可能是该物种在高寒地区恶劣的繁殖环境中实现适合度最大化的一种适应策略。

This study aimed to explore the evolutionary significance of flowering phenology and floral longevity of Stellera chamaejasme by measuring the flowering phenology and floral longevity at different biological levels(i.e.,single flowers,inflorescences,and individual)in a natural population in the alpine grasslands on the eastern edge of the Qilian Mountains.The results showed that the studied population of S.chamaejasme flowered from mid-June to late July,and the flowering durations at the levels of population,individual,and inflorescence were 35 d,18.97 d,and 9.80 d,respectively.The indexes of flowering synchrony at the individual and inflorescence levels were 0.86 and 0.78,respectively,with only one flowering peak at each level.The floral longevity at both the individual and inflorescence levels was significantly negatively correlated with the first flowering date.The floral longevity of single flowers significantly differed with position on an inflorescence;it was the longest for marginal flowers,shorter for flowers in the middle of the head,and the shortest for top flowers(i.e.,flowers at the center of the inflorescence).In conclusion,S.chamaejasme was characterized by a“mass-flowering pattern,”and the floral longevity varied with flowering time and flower position on an inflorescence.This was likely an adaptive strategy of the species to maximize reproductive fitness in harsh alpine environments.