| Amygdalus ledebouriana Schleche is a relict species in Xinjiang which has been listed in the national key protected plants. In order to explore the ecological adaptability of A. ledebouriana, chose the Baerluke hill(population?) and Buerjin(population?) as the study object. The results were showed below:(1) Microspore and male gametophyte of flower bud in A. ledebouriana was observed and researched by paraffin section method. The results indicated that the male sporogonia begin to differentiate in the late August, the primary sporogenous cell formed in early September and Secondary sporogenous cell formed in mid-September. In late September, endothecium, middle layers and tapetum formed which composed microsporangium wall with the epidermis. Microspore mother cell stage was formed of secondary sporogenous cell with mitosis. Then the tapetum was bigger with irregular shape. Subsequently, microspore began to stop differentiation. In mid-March, microspore began to the first meiosis and entered dyad stage. While the cytokinesis and cell wall were not found in the dyad. The microspore tetrad was formed in early April and the cytokinesis was of simultaneous type. At the stage of microspore tetrad, the tapetum began to degenerate. In mid-April, the mononuclear pollen stage was formed and the tapetum was almost disintegrated. In late April, the pollen grains were maturing with 2-celled. The cell wall of anther separation and protoplasm most begin to dissolve. The cleft region between 2 locules leaving only smaller epidermal cells connected, and most of the anther cells disappeared after anther dehiscence. The above results suggested that the sexual cells differentiation of flower bud in wild almond concentrated from late August to late April of next year and it had dormancy from late October to mid-March.(2) The breeding system of A. ledebouriana was studied by field observation, fluorescence microscopy observation, artificial pollination test and statistical analysis methods. The results showed: the initial bloom stage of population?in late April,and it entered the end of florescence in early May. Flowering process of single flower lasted for 8 days and the corolla diameter was(24.79±0.40) mm; The pollen viability was 96.88% at the beginning, half pollens lost activity 17 days later, and all pollens lost activity until 28 th day later; Stigma had highest receptivity from 1 to 3 day at blossoming stage, lasting 7 days; The outcrossing index was 3; Pollens in both self-pollination and cross-pollination germinated on the stigma, and pollen tubes could reach the ovary after 59 hours in cross-pollination. The study of artificial pollination showed that both self-pollination and cross-pollination were fertile, which needed insects as pollination media. The above results suggested that the breeding system is self-compatible, needing pollinators.(3) To explore the pollination and biological characteristics of the A. ledebouriana, an observation was conducted about their species of visiting insects, visiting frequency, and behavior on the flowers. The results were as follows: there are 26 flower-visiting species of population I,11 species of them belong to Apidae. There are 10 flower-visiting species of population? and they are the same species with population I. Scanning electron microscope for the flower-visiting insects of two populations showed that the flower-visiting insects of population?carry 2 kinds of pollen at least, the flower-visiting insects of population?carry only 1 kind of pollen. There are 17 kinds of plants that flowering the same time with Amygdalus ledebouriana Schleche in population I, mainly including Asteraceae, Rosaceae, Liliaceae. There are only 10 kinds of plants that have the same flowering time in population ?, mainly including Liliaceae, Rosaceae. Population has the higher setting rate compared with population ? ?. These results suggested that the less species of flowering-visiting insects probably is one of the factors to affect the reproductive success in population ?. |
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