This experiment was carried out to investigate the green algae resources and their lipid production in Dai Lake. Six species of algae from the Dai Lake of Chongqing in China had been isolated, purified and cultured. They are Ankistrodesmus acicularis, Ankistrodesmus convolutus, Chlorella ellipsoidea, Chlorella vulgaris, Kirchneriella sp. and Scenedesmus quadricauda. After being cultured for 44 days, the growth condition of algae reached the stationary phase. The lipid productions of six species orderly were 25.0%, 22.7%, 19.7%, 20.3%, 15.4%, 16.7% respectively.

The rhizosphere of mulberry in the rocky desertification regions has diverse arbuscular mycorrhiza fungi(AMF).In an investigation reported in this paper,three genera of AMF(Glomus,Acaulospora and Gigarspora)with sixteen species were identified according to their morphological characteristics,of which Acaulospora and Glomus were dominant genera around the rhizosphere of mulberry.Virus-free mulberry seedlings which had grown in experimental ponds in a netted chamber for 2 mouths were inoculated with Glomus mosseae,Glomus intraradices and Acaulospora scrobiculata separately,and mycorrhizal colonization rate,mycorrhizal dependency,growth and photosynthetic characteristics of the inoculated and uninoculated seedlings were measured after cnoculation for 45 day.The results showed the most colonization rate of mulberry roots was(38.67 ± 1.44) % and the most mycorrhizal dependency of the mulberry seedlings was(203.03 ± 14.93) %.The inoculated mulberry seedlings grew significantly better than the uninoculated control in the respects of seedlings height,taproot length,leaves per plant,area of the fifth leaf,fresh weight and dry weight of the plant.The content of chlorophyll net photosynthetic rate,transpiration rate,stomatal conductance of AMF-inoculated mulberry were significantly higher than those of non-AMF-inoculated plants.The above research results confirmed that the inoculants mulberry was highly dependent on AMF.AMF significantly enhanced the root absorption capacity,improved leaf photosynthesis and promoted the growth and development of the seedlings.A lot of vigorous seedlings of mulberry mycorrhizaed were harvested in the experimental ponds.

PEG6000 was used to simulate drought with different soil water potentials(0,-4.3,-5.1,-6.5 and-8.4 Mpa).Mulberry saplings of similar size and vigor cultivated for 450 days were inoculated with Gigaspora rosea,and the inoculated(F+) and the non-inoculated(F-) saplings were transplanted into their respective drought stress matrices.Three days later,their photosynthetic parameters and drought chemo-physiological indexes were determined.The results showed that after inoculation with AM fungi the mycorrhizal colonization rates of mulberry root tips gradually increased up to 150 days and remained largely stabilized at(83.27±2.55)% thereafter.The promotion effect was the most remarkable after inoculation for 90 days.Root vigor increased with soil water potential,being the maximum with a water potential of-6.5 Mpa for the control(F-),but continued to increase for the inoculation treatments(F+).The enzyme activities(SOD,POD and CAT) of F+ first increased with increasing stress intensity and then became stabilized,and were always higher than those of F-.The contents of photosynthetic pigments(chlorophyll a,chlorophyll b,chlorophyll a+b and carotenoid),photosynthetic parameters [photosynthetic rate(Pn),stomatal conductance(Gs) and transpiration rate(Tr)] showed an overall downward trend with increasing soil water potential.However,these parameters of F+ were much higher than those of F-.Osmotic adjustment materials such as proline,soluble sugar and soluble protein increased rapidly with increasing soil water potential,and their contents in the leaves of F+ were significantly higher than those of F-.A possible biochemical mechanism of the drought tolerance of the inoculated mulberry is offered in the paper: AM fungi can enhance the vigor of the root system,promote the activity of protective enzymes,improve the photosynthetic efficiency,increase the contents of osmotic adjustment materials in the leaves and accelerate the growth of mulberry,thus enhancing its ability to withstand drought stress.

In order to explore the ecological reconstruction potential of mycorrhiza-inoculated mulberry plants in rocky desertification areas,simulated water stress environments were created by PEG 6000 at 0,10%,15%,20% and 25% mixed with the substrate.The mulberry saplings inoculated with Gigaspora rosea（F＋） were cultured for 5 months.Then the treated samplings（F＋） and the un-treated samplings（F-） of similar size were potted and subjected to simulated drought treatments.Eight days later,the structure features of the maturation region of the primary roots were examined microscopically in paraffin sections.The investigation showed that the maturation region of the primary root of Morus alba L.consisted of epidermis,cortex and vascular cylinder.Some root hairs grew from the epidermis.The inner-cortex rounded by the Casparian strip was distinct,with xylem and phloem spaced in-between.Under the condition of water stress of 0-10% PEG,the epidermis still existed in F-,and the cells in the cortex were normal.But the epidermis cells died and dropped,and the cells of the cortex were dehydrated and deformed when the PEG concentration was from 10 to 15%.In F＋,epidermis and root hair existed in the 0-20% of PEG.When the concentration of PEG was about 25%,most of the cortex cells were still morphologically normal.The structure of the primary phloem of the stele was affected by water stress in the last period,while the primary xylem was hardly affected by it.It was speculated that the improvement of drought tolerance of F＋ plants was attributed to the fact that inoculation of AM fungi could improve the resistance to water stress by the hyphal net which can absorb more water from the rhizosphere soil and deliver it to the cortex cells by intra-radical mycelium and,as a result,the water needed of plant growth was satisfied,the death or drop of the epidermis was postponed and the cortex cells survived longer.

Based on briefly summarization of the ecological characteristics,ecological threats and the main ecology restoration obstacles in the rocky desertification region,the present paper systematically analyzes the ecological adaptation ability and potential for ecological restoration of mycorrhizal mulberry.Because of good characters in the developed roots,well drought-resistance and tolerance to barren soil,mycorrhizal mulberry is considered as a fast-growing forestry plant in karst environment.It plays an important role in increasing vegetation coverage,promoting environmental improvement and realizing fragile ecosystem restoration and balance.Especially because of the special eco-physiological function of AM fungi(for example,to increase minerals and water absorption) having good corresponding relations with the main ecological obstacles drought and leanness,mycorrhizal mulberry will be a new try to overcome the barriers of vegetation restoration in rocky desertification area.Mulberry that inoculated with arbuscular mycorrhizal fungi will be able to further stimulate the absorption and transportation of mineral nutrition and water,alleviate the poor and drought stress,speed up the soil microbial community construction and increase soil biological activity as well as promote the vegetation positive succession.Usage of mycorrhizal mulberry will provide a new approach for ecological restoration in karst rocky desertification area.

Physic nut (Jatropha curcas Linn., Euphorbiaceae) is one of the hottest biomass energy plant studied by scientists. This paper first reviewed the symbiosis relationship between physic nut and arbuscular mycorrhizal fungi. The researches have showed that diversity of arbuscular mycorrhizal fungi (AMF) exists around the rhizosphere of physic nut. The AMF hyphae colonize root tips of physic nut to develop arbuscular mycorrhizae. The construction of mycorrhizal symbiosis relationship improves the nutritional absorption, promotes the growth and development of seedlings, and enhance the stress tolerance capacity of physic nut. This paper also displays a prospect for mycorrhizal physic nut research in the future, such as mycorrhizal system, the molecular mechanism for stress resistance and gene engineering. As an important resource of biomass energy, mycorrhizal physic nut has a huge exploitation potential and practical value.

通过引入生态补偿的概念,重点对生态补偿缺失的后果及根源进行了分析,最终找出合理的生态补偿的路径。