冬季水淹对秋华柳的开花物候及繁殖分配的影响

开花物候及繁殖分配是植物适应环境的重要因素,为了解长期冬季水淹对三峡库区耐淹物种秋华柳(Salix variegata Franch.)繁殖的影响,研究了长期冬季水淹条件下秋华柳的开花物候和繁殖分配情况。实验在2006年11月份设置了如下处理:对照,完全水淹(植株置于水中,顶部距水面2m)30,60,90,120d和150d。结果表明:(1)对照及各水淹处理的秋华柳花期都较长,在7-11月份持续开花,个体开花进程(开花振幅曲线)呈单峰曲线。(2)冬季水淹对秋华柳群体及个体的开花物候有显著影响。水淹时间越长,始花期越晚,花期持续时间越短(P0.05)。(3)长期冬季水淹下,秋华柳显著降低了繁殖分配比例和全株生物量及单株花序数(P0.05)。(4)开花物候指数与繁殖分配的相关分析表明:始花时间越晚的个体,花期持续时间越短。花期持续时间越短的个体花序数越少,致使繁殖分配越小。总的来说,冬季水淹下,秋华柳通过推迟开花日期、缩短花期持续时间使繁殖分配比例降低,将更多的资源分配到生存力上,是秋华柳对长期冬季水淹的一种适应。同时,在长期冬季水淹后,秋华柳仍保持一定的开花繁殖能力,是其在应用于三峡水库消落区植被构建后产生后代延续种群的前提条件。

The effects of winter water submergence on flowering phenology and reproductive allocation of Salix variegata Franch. In Three Gorges reservoir region

Flowering phenology and reproductive allocation are considered as important fitness factors. To evaluate the adaptation of Salix variegata Franch. to winter submergence, a complete winter submergence (top of plants 2m below water surface) and five submergence durations which included 30days, 60days, 90days, 120days and 150days were set in the experiment, and the flowering phenology and reproductive allocation were analyzed. It was found in the experiment that: (1) S. variegata had long flowering duration, even after winter submergence, which spanned from July to November. And flowering amplitudes of S. variegata were unimodal curves. (2) Winter submergence had significant effects on flowering phenology of S. variegata both on individual and population levels: With the increase in duration of submergence, the initiation time of flowering was delayed, the termination time of flowering was advanced, the flowering duration was shortened, but the flowering amplitudes and the culmination time of flowering were not changed obviously. (3) Long-term winter submergence had significantly decreased the reproductive allocation, the biomass of whole plant, and the inflorescence number of per plant, but the difference of single inflorescence biomass was not significant. (4) The Pearson correlation analysis between the flowering phenology and reproductive allocation indicated that: Individuals with later initiation time of flowering had shorter flowering duration, which also had less inflorescences and lower reproductive allocation. In short S. variegata adapted to winter submergence by allocated resources reasonably, which was essential for the survival and reproduction.