| Styrax tonkinensis (Pierre) Craib ex Hartw is the excellent fast growing species with themany applications.The paper studied the phenophase, development of female and malegametophyte, pollen characteristics and seed biology of Styrax tonkinensis from Jishui, Jiangxiprovince. It have the practical significance to reveal the reproductive biology and develop thebreeding work in future. The main results are follows:(1) Phenological observation: The germination stage of Styrax tonkinensis about in February20,2012. Leaf expansion to the defoliation period, lasting about240days. In the middle of Mayenter the blossom period, early flowering stage to flowers terminal can last about18days, theblossom period can last about7days, single flower exists for about5days. The fruit growthperiod is divided into three phases:"fast growth period"," slow growth period","steady growth".In sunny areas, it growth rapidly, flowering early, have a high fruit-setting rate and quality, leaveslately. The present phenomenon showed that it was the intolerant tree species, suitable for sunnyenvironment.(2) Gametophyte development: Anthers are4-sporangiate, the wall of anther consists oftapetum, middle layers, endothecium and epidermis from inside to out. The development of antherare classified as basic and the tapetum cell is glandular tapetum. The microspore mother cells giverise to isobilateral tetrads by meiosis. Cytokinesis is simultaneous. Mature pollen grain was2-celltype with three germ pores. The ovaryis trilocular. The ovule is anatropous, bitegmious,crassinucellate axile placenta.The chalazal megaspore in a linear tetrad becomes functionat. Thedevelopment of embryo sacs belonged to polygonum type and the stamen was earlier than that ofpistil, they synchronized after blossom.(3) Pollen biological characteristics: Pollen of Styrax tonkinensis with microreticulateornamentation in outer wall is3-colpate, prolate. The average polar and equatorial axis of thepollen is52.33±0.577μm,26.89±0.502μm. Methods of culture in vitro is the most effective to thedetermination of pollen viability. The best combination for pollen germination is10%sucrose,0.05g/L boric acid,100mg/L GA3,3h(treatment4：A2B1C2D3).The viability of Styraxtonkinensis decrease with storage time.-80℃sealed storage is the best storage condition to keep the vitality of pollen. After180d storage，the germination rate of the pollen still was40.97%.(4) Seed biological characteristics: The seed average length，width and1000-grain weight ofthe seeds collected in2011and2012were8.77mm,6.08mm and7.91mm,5.20mm, the136.70g and95.68g, respectively. The seed water absorption ability tested by3different treatmentsshowd that the seed without exopleura had the best water absorption ability. The viability of seedtested by the TTC staining method showed that the viability of seeds collected in2011was97.78%. After stored for one year, the viability of seeds was still as high as94.44%. The seeds ofStyrax tonkinensis had dormancy because of the hard and dense exopleura. Seeds treated with thedifferent concentrations of GA3showed that GA3improved seed germination and seedlinggrowth and the best concentration is1500mg/L.(5) The dynamic changes of seed endogenous hormones: Under the sand and cold storagetest，the contents of IAA and ZR increased at the beginning of stratification then descend as thetime prolongs. But the contents of ABA and GA descend at the beginning of stratification thenincreased as the time prolongs. The change trend of the IAA/ABA,ZR/ABA comment with IAA,ZRseparately.The the contents of ABA in the embryo and endosperm was descend14.50%、11.32%separately under the sand storage with90days, but GA was increased12.64%'15.33%.Theratio of GA/ABA showed the ascending trend ingenerally. The test proved that the seed haddormancy because of the high-concentration ABA, but GA is the main material to promote theseed germination. |
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