The Ecological And Biological Characteristics And Propagation Techniques Of Four Plant Species With Greening Value

Ochna integerrima (Lour.) Merr, Tetrastigma obtectum (Wall.) Planch., Setaria plicata（Lamk．）T．Cooke and Hydrocotyle nepalensis Hook. are four potential garden plants withhigh values of exploitation and utilization. The biological, ecological and physiologicalcharacteristics and propagation techniques of those four plants were determined. The resultscan offer theoretical and technical reference for their exploitation and utilization. The mainresults are as following:1. The blade thickness of O. integerrima was about120.8μm, palisade tissue arrangedclosely and orderly. Its chlorophyll a/b ratio（5.677：1）was higher than theoretic value（3:1）,and the maximal photochemical efficiency of PSII (0.708) was lower than theoretic value（0.832）. Its diurnal net photosynthetic rate in leaves showed a single peaked curve withoutmidday depression. It had high light saturation point（800μmol·m-2·s-1）, light compensationpoint (52.2μmol·m-2·s-1) and low apparent quantum yield (0.020). When the light intensity washigher than light saturation point, the photosynthetic rate did not decline significantly andkept high transpiration rate (1.822mmol·m-2·s-1). It showed that this species was a shadeintolerant mesophyte species. Soaking seeds before sowing, preferably for24hrs, could resultin a high germination rate and earlier germination. In addition, the seeds sown in the peat soilgerminated earlier and had shorter germination time than those sown in sandy soil. However,the latter treatment exhibited a higher final germination rate. It indicated that O. integerrimagrew well in fertile soil or sandy loam. This species was suitable to be planted in tropical andsubtropical areas.2. The blade thickness of T. obtectum was about195.5μm, without derdeveloped palisadetissue and the gaps between the cells were large. The content of total chlorophyll（26.720μg·cm-2） and the maximal photochemical efficiency of PSII (0.818) was high, butchlorophyll a/b ratio（2.829：1）was low. Its diurnal net photosynthetic rate in leaves showeda single peaked curve without midday depression. Meanwhile, T. obtectum had strongutilization ability in water（3.149μmol·mmol-1） and ability to adapt weak light by its lowlight saturation point（600μmol·m-2·s-1）, light compensation point（19.5μmol·m-2·s-1） and high apparent quantum yield (0.058). This showed that T. obtectum prefered to grow undershady and humid condition and had some tolerance in drought, without cold resistance. Inaddition, T. obtectum grew quickly with high rooting rate under cutting propagation. The bestcombination of factors was as follows: the new born twigs without treatment by IBA. T.obtectum was suitable to be planted in tropical and subtropical areas.3. The blade thickness of S. plicata was about51.91-70.04μm. The content of totalchlorophyll（27.966-29.167μg·cm-2） was high, but chlorophyll a/b ratio（2.743-2.906）waslow, and the maximal photochemical efficiency of PSII (0.727-0.778) was lower thantheoretic valu（e0.832）. Meanwhile, S. plicata had strong adaptability to the light environmentby its low light compensation point（13.552-29.721μmol·m-2·s-1）, high light saturation point（700-900μmol·m-2·s-1）and apparent quantum yield（0.066-0.071）. The weak light causeddecreased leaf thickness, palisade thickness, light saturation point, light compensation point,dark respiration rate, chlorophyll a/b and non-photochemical fluorescence quenches of theherb species, but increased the palisade tissue/spongy tissue, apparent quantum yield, thecontent of total chlorophyll, chlorophyll a and b, instantaneous water use efficiency, maximaland the actual photochemical efficiency of PSII and photochemical fluorescence quenches ofthis species. In addition, the effect of different light environment on the sowing and divisionpropagation was not significant and all the plants grew well. Together with its aesthetic effects,this species was an excellent ground cover plant for understory environments.4. The blade thickness of H. nepalensis was about130.7μm, without derdevelopedpalisade tissue. It had thin leaves. The content of total chlorophyll （20.140μg·cm-2） and themaximal photochemical efficiency of PSII (0.811) was high, but chlorophyll a/b ratio（1.308：1）was low. Its diurnal net photosynthetic rate in leaves showed a single peaked curve withoutmidday depression. Meanwhile, H. nepalensis had strong utilization ability in weak light byits low light saturation poin（t600μmol·m-2·s-1）, light compensation poin（t24.08μmol·m-2·s-1）and high apparent quantum yield（0.077）. After cutting, H. nepalensis grew quickly with highsurvival rate under moist and shady conditions. H. nepalensis was suitable to be planted inlow light environment.