Objective To investigate the characteristic of growth and development of vegetable at hypobaric environment and offer the cultivating technique of controlled ecological life support system for higher plant.Methods The means of comparative measurement was adopted to study the growth and physiological characteristic of lettuce under low and normal pressure(40.0 kPa,101.0 kPa),which was carried out with the low pressure plant-cultivating facility.Results Compared with normal pressure,germination rate of lettuce seed was eliminated by 7.62% under total pressure 40.0 kPa and oxygen partial pressure 8.4 kPa conditions;harvest time of lettuce was delayed,so biomass harvested at the same time reduced by 13.67% and content of total saccharide declined;the average rates of photosynthesis and transpiration were lower than those at normal pressure in 30 days after planting(DAP),but which reversed after that;release of C2H4 and shoot height reduced by 38.79% and 11.68%,but leaf area,ratio of root to total biomass and root vigor increased by 15.43%,2.57% and 40.53%,respectively.Conclusion Seed germination,growth and development of lettuce are affected in some degree at total pressure 40.0 kPa and oxygen partial pressure 8.4 kPa,some measures should be adopted to regulate the growth of lettuce.

Objective To select suitable vegetable for use in Controlled Ecological Life Support System for future long-term space missions. Method Five crops of lettuce(four Lactuca sativa L. var.crispa L.and one Lactuca sativa L. var.longifolia Lam), two crops of spinach(Spinacia oleracea L.), one rape(B.napus L.)and one common sowthisthe (Sonchus Oleraceus L.)were grown in a Controlled Ecological Life Support Technique Experimental System. Hydroponic nutrient solution, light, temperature and relative humidity were regulated, CO_2 levels were controlled at 500, 1 000, 1500 and 2 000 ?mol/mol, and light intensity were controlled at 100, 300, 500 and 700 ?mol/(m2?s). Canopy photosynthetic rate, transpiration rate and leaf aera were measured on day after planted (DAP) 25 and 30. Plants were harvested at maturity, and analyzed for total fresh weigh and proximate composition (crude fiber,nitrite and ?-carotene). Result Three crops of lettuce “nenlvnaiyou”, “dasusheng”,“youmaicai” ,and one common sowthisthe were selected. The favorite CO_2 concentration and light intensity 2 000 ?mol/mol, and 700 ?mol/(m2?s) respectively.Conclusion The four crops selected have high productivity, photosynthetic rates and transpiration rates, which can be considered as the basis of the vegetables to be used for future long-term space missions.

Objective A foundation for one of the biological components,Spirulina,to be applied in Controlled Ecological Life Support System(CELSS)would be laid with exploring effects of ionization radiation on the growth of Spirulina.Methods By using the ?-rays of ~(60)Co,Spirulina were irradiated.The dose of the ionization radiation covered 0,0.5,1.0,1.5,2.0,2.5,3.0 kGy.After irradiated,these Spirulina were cultured under the same conditions.The growth state,shape change,photodensity change,photosynthetic efficiency(O2 produced),and trophic physiological indexes of Spirulina or its solution,were observed,measured and analyzed.Its anti-irradiation ability was investigated.Results After irradiared with ~(60)Co ray,the growth rate,photosynthetic O2 produced efficiency,length of fila and other trophic physiological indexes were all affected in certain degree,but as compared to the higher plants,Spirulina have stronger radiation proof and self-rehabilitation capacity.Even if under high radiation condition(3.0 kGy),there was no complete death of cells,and the dose resulted in 50% death of the Spirulina was 2.0 kGy.Conclusion Spirulina has stronger ionization radiation proof and self-rehabilitation capacity,it can be considered as one of the key biological components in CELSS for future long-term space missions.

Objective To study the cultivating technique of wheat under low pressures as to establish the basis of developing hypobaric controlled ecological life support system.Methods Wheat growing experiments under normal and low pressure(101 kPa,50 kPa) were carried out with low pressure plant-cultivating facilities,and the growing indexes of wheat under low pressure,such as photosynthetic rate,transpiration rate,growing status,yield and nutrient contents in seeds were compared with those under normal pressure.Results Wheat grew normally under low pressure as compared with those grown under normal pressure,but low pressure curled leaves of the wheat and caused them to turn yellow at prophase;after 15 d treatment under hypobaric condition,the average rates of photosynthesis and transpiration increased by 9.23%and 11.54% respectively;shoot height of wheat decreased,both tiller number of each plant and the ratio of root in whole plant increased,but harvest time was delayed for about 5 d under low pressure;the biomass and the yield of wheat increased by 5.46% and 4.39% respectively,the contents of protein and total saccharide in seeds also enhanced at reduced pressure,but other nutrient contents in seeds had no significant difference between 101 kPa and 50 kPa.Conclusion Growth of wheat is promoted in certain degree by low atmospheric pressure.

Objective To develop a prototype of low pressure plant-cultivating facility, for studying the growing technique of higher plants under low pressure in manned deep space exploration, so as to lay foundations for establishing controlled ecological life support system (CELSS) in low pressure environment. Methods According to detailed demonstration of technical plan, blueprint design and machining of components, facility installment, debugging, trial operations and verification experiments were carried out. Results Two sets of low pressure plant-cultivating facilities were manufactured, both of them could be used to cultivate higher plant under low or normal pressure. They worked stably and their technical parameters such as temperature, relative humidity, air pressure, O2 partial pressure, CO2 partial pressure and water content of matrix were all monitored and controlled effectively. Conclusion Their main technical indexes meet design and experimental requirements, low pressure plant-cultivating experiments can be carried out with the facilities effectively.

Objective To investigate growing characteristics of plants grown at elevated CO2 concentrations in controlled environment and provide base for determination of biological components in future space controlled ecological life support system (CELSS).Methods Lettuce (Lactuca sativa var.Youmaicai) was cultivated at higher atmospheric CO2 concentration gradient (0.05%～2.0%).Its growing status,physiological characteristics and the content of nutrients were evaluated.Results There were some active effects of elevated CO2 (0.1% to 1.0%) on the average rates of photosynthesis and transpiration of the collective lettuce leaves and the contents of chlorophyll and carotenoid,but excessive CO2 (1.5% and 2.0%) weakened these effects,and even had some negative impacts.Lettuce could grow normally at elevated CO2 (0.1% to 2.0%),average shoot height and leaf area of lettuce plants treated at 0.1%～2.0% CO2 all increased,but the numbers of leaves eliminated gradually.The contents of nitrogen,potassium and Vc in plants decreased,phosphorus content rose and microelement contents had no obvious change in various CO2 treatments.Conclusion The lettuce can grow nearly normally at higher atmospheric CO2 concentration without serious growing inhibition or death,which indicated that the Youmaicai held stronger ability of tolerating higher concentration of CO2,so it's suitable to be determined as a candidate biological component in CELSS.

Objective To investigate the characteristics of higher plant grown in red and/or blue light and test the capability of red and/or blue light emitting diodes(LEDs) used as the artificial lights for plant growth in controlled ecological life support system(CELSS).Methods Lettuce(Lactuca sativa var.Youmaicai) was cultivated in sole white LED,sole red LED and combined red and blue LEDs,respectively.Its growing status,physiological characteristics and the content of nutrients were evaluated,which were adopted to select the best combination of red and blue LED for plant growth.Results Red light promoted the radial growth of lettuce plants,and blue light was propitious to their transverse extension and synthesis of chlorophyll and carotenoid;lettuce plants couldn't grow normally in sole red light;with the gradual increase of blue light proportion(5%~20%),there were some active effects on the growth of lettuce plants,for instance,the improvement of photosynthesis,transpiration and fluorescence(Fo,Fv/Fm and qN),the increasing of contents of chlorophyll,carotenoid and nutrients and the enhancement of total biomass;the adverse effects of blue LED on the growing of lettuce plants appeared gradually with the addition of blue light(25%~50%).Its biomass of shoot decreased significantly,which induced the increase of the ratio of root/shoot.Conclusion The combined red and blue LEDs is propitious to lettuce(var.Youmaicai) growth and the best lighting condition is the combined 90% red and 10% blue light.