Lea-Cox J D, Stutte G W, Berry W L, Wheeler R M
Dynamac Corporation, Kennedy Space Center, FL 32899, USA.
Life Support Biosph Sci. 1996;3(1-2):53-9.
Existing control systems for pH and nutrient supply in hydroponic space plant growth units and bioregenerative life support (BLS) systems require acid and base additions to correct plant-induced charge imbalances in the nutrient solution. Plant growth is dependent on nutrient availability, and the active uptake of ions by roots changes the pH of the nutrient solution. This change in pH is an integrated response to nutrient and organic ion influx/efflux by the plant. Plant nutrient requirements, as a function of crop development and driven by specific environmental conditions, influence the magnitude of the charge balance requirement. Nitrogen is the dominant nutrient taken up by plant species. If the daily crop nutrient (N) requirement at each developmental stage is known, and the daily addition of nutrients (relative addition rate = RAR) to the plant growth system is calculated, controlling the daily addition of ammonium (NH4+) and nitrate (NO3-) offers a mechanism whereby pH fluctuations in the nutrient solution could be largely minimized and controlled, reducing acid or base additions to the system.
现有的水培太空植物生长单元和生物再生生命支持（BLS）系统中的pH值和养分供应控制系统需要添加酸和碱来纠正植物引起的营养液中的电荷失衡。植物生长依赖于养分的可利用性，根系对离子的主动吸收会改变营养液的pH值。pH值的这种变化是植物对养分和有机离子流入/流出的综合反应。植物的养分需求，作为作物发育的函数并受特定环境条件驱动，影响电荷平衡需求的大小。氮是植物吸收的主要养分。如果知道每个发育阶段作物每日的养分（N）需求，并计算出向植物生长系统中每日添加的养分（相对添加率 = RAR），那么控制每日铵（NH4+）和硝酸盐（NO3-）的添加量，就能提供一种机制，从而在很大程度上最小化和控制营养液中的pH值波动，减少向系统中添加酸或碱的量。
