中文摘要：

采用定株观察，运用花粉-胚珠比、联苯胺-过氧化氢法、杂交指数和套袋实验等方法，对紫茉莉（Mirabilis jalapa L．）的开花状态及繁育系统进行了研究。结果表明：种群花期一般为6—10月，单花花期一般为2—3d；单花花期依其形态和散粉时间可分为散粉前期、散粉初期、散粉盛期、花闭合期、凋谢期5个时期；在花闭合时期，晴天有66．80％的花的柱头在闭合花冠内，阴天时有81．65％的花的柱头在闭合花冠内，雨天柱头在闭合花冠内的花可达99．22％；按照杂交指数，其繁育系统属于自交亲和，有时需要传粉者；P／O值约为269，判断繁育系统类型属于兼性自交；开花6h左右，柱头的可授性最强，此时花粉活力、置落在柱头上的花粉数及其在柱头上的萌发率都达到最高。套袋实验显示，紫茉莉自然条件下没有无融合现象，繁育系统为自交、异交亲和，以自交为主，但有时也需要传粉者；在长期的环境选择压力下，紫荣莉选择将更多的柱头留在闭合花冠内，是其对不利环境条件的一种适应进化策略。

英文摘要：

Flowering and breeding characteristics are important for understanding plant population reproduction. In this paper, the flowering dynamics and breeding system of Mirabilis jalapa L. were studied by using the data of pollen-ovule ratio （ P/O）, pistil recipient phase, out-crossing index （OCI）, pollen viability, numbers of pollen grains and their germination ratio on stigma, and emasculation. The results showed that the flowering period of M. jalapa was about four months （from June to October）, and the life span of individual flower was generally 2-3 days. For each flower, the flowering process could be divided into five periods, i. e. , pre-dehiscence, initial dehiscence, full dehiscence, perianth closure, and withering, based on the changes in floral morphology and anther dehiscence. In the period of perianth closure, the percentage of stigma inside of closed perianth was 66.80% when it was sunny, 81.65% when it was cloudy, and 99.22% when it was rainy. The floral diameter was 22-28 mm. In the majority of M. jalapa, there was a temporal isolation between male and female organs within the same flower, i. e. , the gynoecium ripened early, stigmas and anthers were arranged at the same height, and the out- crossing index （OCI） was 3. However, in a lesser percentage of flowers, there were temporal and spatial isolations between male and female organs within each flower. The gynoecium ripened early, with an out-crossing index （OCI） of 4. According to the criteria put forward by Dafni, most of M. jalapa individuals had the breeding system of self-compatible and only requiring polli-nators sometimes, and fewer were of outcrossing, partially self-compatible, and requiring pollinators. The pollen-ovule ratio （P/O） was approximately 269. Based on Cruden＇ s criterion, the breeding system could be termed as facuhative autogamy. For about 6 hours after flowering, when stigmas were at the highest receptivity, 56.29% of the pollen was viable. According to the results of emasculation, bagging, and artifi