|其他摘要||Capparis spinosa L. (Capparidaceae) is a woody perennial, with an extended flowering period. It is observed that the proportion of male flowers and perfect flowers are different in population even in the same plant. And the proportion is different in whole growing season. Each flower has both short and long stamen.
In order to investigate proportional change rule and biological adaptability mechanisms under the extended flowering period, cognize evolutionary sense of heteranthery functional differentiation. The adult individual plant and population of C. spinosa were chosen as research objects. Reproductive characteristics of extended flowering, the relationship between male and perfect proportional and sexual reproduction efficiency, compare the morphology, number and the colour of same stamen between two kinds of flowers, the morphological characteristics, pollen vigor, the quantity of pollen, the function and the insect visiting between shorter and longer stamen were totally observed and compared. In order to explain reproductive habits and ecological adaptation mechanisms of C. spinosa, reveal if different proportion of male flowers and perfect flowers impact on fruit setting, the evolutionary sense of the morphological and function of heteranthery. It provide new theoretical basis for reproductive biology research and the evolutionary sense of the morphological and function of heteranthery of C. spinosa under selection pressure.
The main results were as follows:
(1) The flowering period was approximately five months long, during this period, two main and overlap flowering peaks emerged. Several significant differences between the two peaks were found: the number of flowers and duration of the flowering period for male flowers were identical in both peaks, but differed for perfect flowers (contain stamens and pistil) ;
(2) The filaments of both long and short stamens in male and perfect flowers in the first peak were longer than those in the second, whereas anther length showed the opposite trend;
(3) Pollen vitality of C. spinosa was highest (>80%) 2-6 h after anther dehiscence, as pollen grains remained viable for 20h. No difference in the pollen vitality of both male and perfect flowers was observed. The stigma receptivity of perfect flowers was highest 4-8 h after the flower opened. It lost receptivity 16-18 h after opening and the petals had wilted. No difference in stigma receptivity between the two peak flowering periods was apparent.
(4) The frequency of fruit set and size in the first peak was respectively higher and larger than the second; and the seeds produced in the first peak were smaller and lighter than the second.
(5) The proportions of male and perfect flowers were manipulated manually and the impact on fruit set and quality, and on seed number and quality, was assessed. Fruit set differed significantly among the different flower proportions. Under a male flower: perfect flower ratio of 5:5, the male resources: female resources ratio was 2:1 and fruit set was the highest recorded (82%). The relative proportions of male and perfect flowers significantly affected fruit and seed quality. Fruit were largest and heaviest, and number of seeds was highest, under a male flower: perfect flower ratio of 2:8, whereas the fruit were smallest and number of seeds was fewest under a male flower: perfect flower ratio of 9:1. Under male flower: perfect flower ratios of 4:6, 3:7, and 7:3, fruit set was lowest but the seeds were largest and heaviest, which indicated that fewer seeds could receive higher resource allocation by the plant. This study reveals why C. spinosa products perfect flowers not female flowers.
(6) The length, colour, number of pollens of single anther, fertile pollen rate and the insect visiting of the same stamen had no significant differences between male flowers and perfect flowers. Through the artificial pollination experiment, the perfect flowers with no stamens were pollinated the pollen of the longer stamens in two kinds of flowers, the fruit rate and the quality of fruits had no differences between two kind of flowers. However, the number of seeds from the pollen of longer stamens of perfect flowers were lower than the number of seeds from the pollen of longer stamens of male flowers. The fruit rate from the pollen of shorter stamens of perfect flowers were higher than that from the pollen of shorter stamens of male flowers, but the quality of the fruits and the seeds, the number of seeds in single fruit had no significant differences between two kind of flowers. This study provides the rationale and the basis to compare the morphology and the function between longer stamen and shorter stamen in the same flower.
(7) Male and perfect flowers all had longer and shorter stamens in a single; the number of the stamen, the colour of the filaments and the number of pollen in a single flower had significant differences between longer and shorter stamen. The number of longer stamen of pollen in a single flower was more than those of shorter stamen. Pollen vigor had no difference between longer and shorter stamen. The insects visited frequency of longer stamen was higher than that of shorter stamen. The pollen of longer stamen and shorter stamen were respectively used for hand pollination, it was proved that the fruit and seed rate from the pollen of longer stamen were higher than that of shorter stamen.
(8) In short, long- and short-level stamens of C. spinosa could be described as "pollinating" stamens. Their main function were povide pollen and visiting by insects were the main function of longer stamens, and the shorter stamens could improve the male resources guarantee in the bad weathers, provide a more convenient space for pollen captured and to the maximize pollination probability, increased the single insect visiting time. This research provides an evidence to reveal the morphology and function of dimorphic stamens in C. spinosa. It has shown the evolutionary sense under the selection pressure.|