Research On Reproductive Ecology And Analysis On Fruit Quality Of Mangrove Avicennia Marina

Based on the field surveys and experiments, the reproductive ecology of Avicennia marina was investigated and the fruit quality was analysed in this paper. The results were as follows:(l)Mean flower success of 57.61%, mean fruit set rate of 3.03% were counted at A. marina population of Daguansha.This species tends to be cross-pollinated by insects. Emasculation and perianth removal showed that the vivid corolla was more attractive than the floral scent to pollinators. There was no parthenocarpy in this species.Relatively high flower success, along with relatively low fruit set rate, indicated that inhibition in the procession of pollination and fecundation resulted in low fruiting rate in this species. A. marina is a typical r-strategist.(2)The floral syndrome of A. marina, such as floral scent, colorful corolla, and outstanding anthers, can facilitate entomophily. The relationship between A. marina and pollination agents belongs to "generalization type". A least 9 species of insects were observed to visit the flowers of A. marina, and they were believed to be potential pollination insects, identified as insects of Diptera , Hymenoptera and Hemiptera-Heteroptera. A. marina seems without its faithful pollinators.(3) Peak budding time ranged from the late May to late July. Mostly A. marina blossomed from mid-June to mid-July and most of the flowers withered from early July to mid-August. Peak fruiting time began in early August and ended in late September.(4) Oligochroa cantoonella tends to be an oligophagous insect, whose bite can wither away a great deal leaf and twigs of A. marina and then reduce the fruit yield. The content of nutritional components and tannin in plant material may be related to the food habit of O. cantoonella.8.27% of buds in A. marina population of Daguansha were damaged by the insects.The fruits were mainly harmed by O. cantoonella. The development of seeds was hampered by the insects as they bit the cotyledons in the seeds. The pests have pervaded on coastal areas of Guangxi, Guangdong and Fujian, at any rate.(5)There was no significant correlation between annual gross fruit yield of the population and latitude. Correlation coefficient between annual gross fruit yield of the population and degree of insect pests was -0.796, with a disrelated probability of 5.8%. Human disturbance, plant diseases and insect pests were important exoteric factors influencing on population fruit yield of A. marina. Waterflooding can greatly restrain insect pests of O. cantoonella.(6)Annual population fruit yield of Daguansha was about 160t FW/a (2.4 t FW/haa), and 37.5% of which ( about 60t FW) were harvested by local residents. Each year 85 propagules per square meter can be promising recruits of the population or establish a new population.62t of the fruit (Lanqian) were sold at Beihai's market each year, and transaction volume reached 0. 1929 million Yuan.(7)Fruit shape, fruit weight as well, was different significantly(p<0.05) in each A. marina population along SE coastal area of China. The mean fruit weight of A. marina was 2.5265±0.8232g. Significant difference occurs betweenfruit weight and size index. Growing in mud are advantageous to the development of fruit of A. marina.Fruits of A. marina can be categorized as three groups based on the results of clustering analysis. Group One are all big size fruits, namely fruit of Qinzhou Harbour; Group Two are middle size fruit, mainly found in Yuanxiao, Fangchenggang and Shankou; Group Three are small size fruit, found in Daguansha and Deyao, Zhanjian(8)Results of propagules cultivating under controlled environment showed that:Light is not needed for pericarps'dehisce of propagules, and low salinity is conducive to pericarps'dehisce.Propagules of A. marina can grow roots in dark or under natural light in sand culture. Low salinity can benefit the rooting and growing of seedling in the species. Salt excretion can be strengthened with the increase of salinity of culture water. Seedlings of A. marina grew higher in dark, even if acerose, tender and underdevelopment mechanical tissue stems are developing.Propagules of A. marina can tolerate anoxic environment for a long time during inundation. But the growth of stem and leaf are slowed down and elongations of root are hindered.In conclusion, low salinity are good for regeneration of A. marina population.(9)High concentration of total soluble sugar, total amino acid (TAA) and low concentration of tannin, crude fibre were determined in the flesh (seeds) of A. marina. The insect and crab favored the flesh (seeds) of A. marina due to its allocation characters of chemical component.The seeds of A. marina were found contains comparatively high level of total soluble sugar and total amino acid (TAA), and comparatively low level of tannin and crude fibre. Such contents in the seeds make them favorable foods of insects and crabs, and hence the seeds are vulnerable to these animals.Contents of crude fibre, crude fat and tannin were much higher in pericarp than in flesh (seeds), but the content of total soluble sugar is lower in pericarp. High concentration of crude fibre in pericarp helps to strengthen the texture of the seed and then form a protective shield for the seed.The relative concentration of total soluble sugar and tannin in A. manna's flesh (seeds) was found drop sharply after the seed was cooked and immersed in water overnight, but relative concentration of other compounds (starch, crude fibre, crude fat and TAA) increased.The fruit of this specie tends to be one of the most valuable mangrove fruit, due to it's widespread and allocation feature of ingredient in fruit, namely high content of edible component and low content non-edible component.