No abstract

Flowering phenology and reproductive allocation are important factors to adapt to the environment. The article studied the flowering phenology and reproductive allocation of Fagopyrum dibotrys. Fagopyrum dibotrys flowered from August to November, mainly in September, centralized flowering contributes to insects pollination and improves reproductive success; Fagopyrum dibotrys flowered 1 to 2 days for a single flower, 85 days for the population. Long鄄styled capitulum flowered 15 to 26 days, short鄄styled capitulum flowered 14 to 27 days, the difference is not significant; The flower number of the long鄄styled single capitulum is 26 to 131, the short鄄styled capitulum is 36 to 147, the difference is not significant. Flowering dynamic of F. dibotrys忆s long鄄styled and short鄄styled capitulum presented unimodal curve,long鄄styled and short鄄 styled capitulum both reached maximum 11days after flowering, was 7. 30% and 7. 20% respectively, and the two floral morphs maintained high synchronization of flowering, contributing to increase the reproductive adaptability. Pistil and stamens length exhibited very significant negative correlation in the same floral morphs, but the total length showed no significant difference, which showed that there is a trade鄄off relationship; Fagopyrum dibotrys忆 s vegetative organs and http: / / www.ecologica.cn reproductive organs biomass existed no significant difference between the long鄄styled and short鄄styled, while their floral biomass and plant biomass showed very significant difference. F. cymosum忆s floral biomass allocation ratio of the long鄄styled is significantly larger than the short鄄styled, but the total biomass showed no significant difference, which showed that there is a trade鄄off relationship in Fagopyrum dibotrys忆s vegetative growth and sexual reproduction.

Perennial plants that normally experience dormancy during winter may be subjected to more cycles of freeze鄄thaw caused by warming winter. We explored the physiological mechanisms of adaptation of white clover, Trifolium repens Linn, to freeze鄄thaw stress. In late fall of 2009, uniform plots of white clover grown in a natural environment (NE) were covered with a plastic house (pH) to simulate the effect of a warmer winter or left uncovered (control). During the winter and following spring, growth capacity and physiological indices related to resistance to adverse environment were measured in leaves of white clover grown in both conditions. In the winter of 2009, the average temperature ranged from below zero (-10益) to 7益 in the NE during which leaves experienced thawing鄄freezing鄄thawing鄄freezing, and above zero (from 1 益 to 7 益) in the pH where leaves were never frozen. In late fall of 2009, all white clover was of uniform height. But in spring 2010, plants grown in the PH (26 cm) were 3 times taller than those in the NE (8 cm). This difference in height disappeared by June 2010. In winter, the relative membrane permeability, MDA(malondialdehyde) , proline, and soluble