<正>坦桑尼亚姆特瓦拉地区的腰果产量在过去3年内(20072010年)急剧减少,根本就没有达到预计的250万t。Nariendele大学的一位研究者Shamte

To determine if in a drought environment there was an adaptation for Acacia richii due to rhizobia,this experiment analyzed the accumulation of metabolites,such as proline,soluble sugar,and chlorophyll,after inoculation with SMD rhizobia separated from Tephrosia candida,YHH from Leucaena leucocephala and TWXS from A.richii under artificial drought conditions in a PEG-6000 solution.The contents of PEG-6000 were 0(control),0.010,0.025 and 0.037 respectively.Results showed that different rhizobia increased metabolite accumulation in drought conditions,but there were different levels of accumulation depending on rhizobia strains.The rhizobia SMD had a stronger potential to promote seedling resistance in a drought environment than rhizobia YHH and TWXS.Thus,it is advantageous to choose rhizobia to promote growth of A.richii in drought conditions.[Ch,3 tab.16 ref.]

Legume species and their nodulations in the wild in dry-hot valley were survered,soils physical-chemical characters were analyzed.15 species of Legumes trees were examined of nodulation in the dry-hot valley.Among them,each leguminous root nodule showed its own nature in different places,even in the same place;the root nodule exhibited its own characteristics,such as quantity,shape,size and color.There were 9 Legume plants with nodules.But the nodulation-rate was low and a high proportion of these root nodules were non-infected and shrunken.18 strains of root nodule bacteria from the trees were isolated through the isolation,purification and identification.15 soils were analyzed from the dry-hot valley.The experiment showed that the nodulation legume trees growed in the loam soil with neutral pH and had significant higher content of soil organic matter,and had clearly differences in N(0.123 2~0.311 6 mg.kg-1),P(0.002 7~0.122 2 mg·kg-1),and K(2.427 5~0.140 8 mg·kg-1).So,in the dry-hot valley,all kinds of special environment conditions infected the nodulation of the legumes trees,such as temperature,ecology condition,soil,soil organic matter, and the content of available N,P,and K.

In this study,12 strains isolated from the root nodules of woody legumes in the various regions of Jinshajiang River dry-hot valley were used to study the drought-hot tolerance by adding Polythylene glycol 6 000 to YME brouth medium and controlling the temperature.The results indicated that: the 12 strains had different tolerance ability to drought-hot,such as P5-1,P5-6,P5-8,P6-11,Y8-12,P5-5,Y6-13,P5-7,and lots of stains could resistant temperature 40℃ such as P5-1,P5-2,P5-6,P5-7.In the brouth medium which adding PEG,there were a lot of strains had indicated the strong tolerance ability.From this study of resistance,P5-1,P5-6,P5-7 not only could grow at temperature 40℃ but also in the condition of-8.71×10~5 Pa and 35℃.

Much more attention has been paid to the rhizobium,which are symbiotic bacteria forming symbiosis with leguminous plants and conducting nitrogen fixation in the nature.Application of the drought-tolerance of rhizobium to hot-arid regions is helpful to provide means and ideas of improving vegetation growth and promoting productivity of agriculture in these areas.The research advances in drought-resistance of rhizobium were reviewed from the point of physio-chemical view and from the angle of gene engineering.

Dry-hot valleys(DHV) are mainly located in the deeply incised valleys along the upper streams of some national and international rivers, such as the Yangtz River,the Pear River,the Lancangjiang(Mekong) River,and the Red River etc.Because of the unstable geological texture,shallow soil,and a half-year long dry period with little rainfall,the ecological environment in DHV areas is quite vulnerable.Moreover,the ecological environment in these areas has been severely influenced by over farming due to population expansion,and it has become extremely fragile.The primary vegetation in the local area of dry-hot valleys used to be evergreen broad-leaved forests and deciduous broad-leaved forests,which had been denuded in the history.The current local vegetation is mainly the degraded secondary vegetation composed of savanna styled grassland and succulent thorny shrubs.A series of pilot research projects demonstrating new silviculture techniques for vegetation restoration in DHV areas have been implemented.However,it is still hard to carry out large scaled afforestation programs in DHV areas.

通过对昆明世博园开园5a后的病害种类调查及植物病害病原种类鉴定,与建园前后4个阶段病害调查比较,确定世博园云南省新记录病害8种和外来潜在危险性病原的种类,并提出植物病害监测及控制建议.