The effects of winter water submergence on flowering phenology and reproductive allocation of Salix variegata Franch. In Three Gorges reservoir region
冬季水淹对秋华柳的开花物候及繁殖分配的影响

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.