红蓝LED光照强度对密闭生态系统中生菜生长状况及光合速率的影响

研究利用红蓝LED进行不同光照强度下的生菜培养实验。通过设置不同生长期的对照试验,确定了CELSS中生菜的最佳收获期。试验结果显示,生菜光合速率（Pn）和产量均随光照强度增加而上升,但增幅逐渐变小;通过公式拟合,光照强度达到556μmol·m-2·s-1时,继续增加光照强度产量不再增加,同时光能利用率随着光照强度的增加而降低。在保证生菜供氧能力及产量满足乘员对氧气、食物需求的前提下,选择合适的光照强度水平,可有效提高系统的能源利用效率。出苗后第40天为最佳收获期,此时收获,生菜的日产量和光能利用率最高,营养品质最好。

Effects of the Red and Blue LED Light Intensity on Lettuce Growthand Photosynthetic Ratein a Closed System

A lettuce cultivation experiment was performed under different light intensities with 90% red ＋ 10% blue LEDs. Meanwhile, contrast experiments with different growth period were set to de- termine the best time for harvest. As a result, the photosynthetic rate （Pn） and yield of lettuce rose as the light intensity elevated, but the rising extent was smaller and smaller. By polynomial curve fitting, we know that when the light intensity reaches 556 pomol·m-2 ·s l, further increase of the light intensity won＇t raise the yield any more. Meanwhile, when the light intensity increases, the light efficiency will decrease. So, at the premise that the demand for 02 and food could be satisfied, selecting appropriate light intensity can raise the energy use efficiency. The yield per day, light effi- ciency and nutrition quality of lettuce with a growth period of 40 days were the best. Thus harvesting the lettuce at the 40th day is the most efficient.