Studies on factors limiting the distribution and sexual reproduction of Oxalis corymbosa DC. in Taiwan
Date Issued
2007
Date
2007
Author(s)
Tsai, Meng-Ying
DOI
zh-TW
Abstract
Oxalis corymbosa is an exotic plant in Taiwan. In spring, O. corymbosa thrives in parks and wastelands, but is found only in shady environment during summer season. In addition, O. corymbosa has more populations in northern than in southern Taiwan. Though O. corymbosa has been observed producing capsules in its native habitat, it has no fruit in Taiwan and uses vegetative reproduction by bulbs. There are two objectives of this study: first, to examine the response of O. corymbosa under different irradiance (PAR) and watering regimes; secondly, to study factors limiting seed-set of O. corymbosa in Taiwan. Results showed that plants under two different light treatments in spring had no significant difference in biomass and photosynthetic parameters. But plants of O. corymbosa grown under full light and well water condition in summer had greater biomass than those in shade. Under high light and high temperature condition, leaves of O. corymbosa suffered obvious photoinhibition. Grown under drought treatment, O. corymbosa had significant reduction in light-saturated net photosynthetic rate and biomass. These results suggest that low soil moisture may be an important factor restricting the growth and distribution of O. corymbosa. The flowers of O. corymbosa have tristyly in its native environment. To investigate flower morph, I surveyed O. corymbosa populations in Taiwan during 2005-2007. Long morph individuals were not found, and mid morph individuals (96.7%) were found to have the greatest proportion in Taiwan. In addition, most of short morph individuals had white and sterile anthers. However, the percentage of vital pollen of O. corymbosa (~4.0%) was much lower than that of O. corniculata (~54.9%, the native congener of O. corymbosa in Taiwan). The analysis of nuclear DNA content revealed that O. corymbosa individuals of different flower morph have same chromosome numbers. After examining paraffin section of anther, I found that white anther had abnormal tapetum. Therefore, possible causing white anther is not due to odd chromosome set, but is caused by the abnormal tapetum. Greenhouse and growth chamber experiments also showed that temperature and irradiance could influence the percentage of vital pollen of upper stamen. Plants under low light treatment had lower percentage of vital pollen. The adequate temperature and irradiance may increase the percentage of vital pollen of upper stamen, but the situation will not improve the fruiting probability of O. corymbosa due to the absence of long morph individuals in Taiwan. Since O. corymbosa has self-incompatibility and successful pollination is restricted within legitimate pollination, the absence of long morph individuals in Taiwan and low percentage of vital pollen may be important factors contributing to the fruiting failure of O. corymbosa in Taiwan.
Subjects
紫花酢漿草
光度
水分
有性繁殖
花粉活性
Oxalis corymbosa
light
water
sexual reproduction
pollen viability
SDGs
Type
other
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