红光和蓝光是植物进行光合作用和光形态建成的主要有效光谱, 且红蓝发光二极管(LED)成为植物工厂的主流光源。 为实现LED连续光照在植物工厂中的应用, 探明植物对红蓝光谱连续光照的响应特征及其与栽培氮形态和LED红蓝光质的关系十分必要。 在环境可控的植物工厂内, 采用水培方法和ICP-AES测试技术, 研究了采收前LED红蓝光连续光照(CL)对不同光质与氮形态水培生菜生长及营养元素吸收的影响。 在光照强度150 μmol·m-2·s-1下, 试验设置了3种红(R)蓝(B)光质: 2R∶1B(Q2∶1), 3R∶1B(Q3∶1)和4R∶1B(Q4∶1), 以及2种氮形态: 80% 硝态氮(N80%)和100% 硝态氮(N100%)。 结果表明, CL前, LED光质与营养液氮形态互作处理对水培生菜的地上干重具有显著影响, 对地上鲜重及根鲜干重无显著影响, 对N, C, P, K, Ca, Mg, Fe, Mn, Cu, Zn的含量及积累量均无显著影响。 CL后, 光质与营养液氮形态互作处理对水培生菜的根鲜重与根干重有显著影响, 对地上鲜干重的影响无显著差异, 只对N, P的含量, N, P, Fe, Zn的积累量有显著影响。 CL对水培生菜的生物量, 矿质元素含量及积累量有显著影响, 与CL前相比, 地上鲜重, 根鲜重, 地上干重及根干重均显著增加； 各营养元素含量均有不同程度的降低趋势, 其中CL显著降低了N, P, Fe, Zn的含量, 而对于C, K, Ca, Mg, Mn, Cu的含量无显著影响。 CL均显著提高了N, C, P, K, Ca, Mg, Fe, Mn, Cu, Zn的积累量。 综上所述, CL前, LED光质与氮形态对生菜地上干重具有显著影响, 对各营养元素的含量及积累量均无显著影响。 CL后, LED光质与氮形态对根鲜干重具有显著影响, 对N, P的含量及N, P, Fe, Zn的积累量具有显著影响, N80%Q4∶1处理积累的量最高。 与CL处理前相比, 水培生菜的地上鲜重, 根鲜重, 地上干重及根干重均显著增加； CL显著降低了N, P, Fe, Zn的含量, 显著提高了N, C, P, K, Ca, Mg, Fe, Mn, Cu, Zn的积累量。 因此, 栽培光氮条件N80%Q4∶1和采前LED红蓝光连续光照结合可以提高水培生菜营养元素含量。

Red and blue light are the main active spectra of plants for photosynthesis and photomorphogenesis. Also red and blue light-emitting diodes (LEDs) have been the dominant light source for plant factory. Therefore, the response characteristics and mechanism of plants to continuous light of red and blue spectrum need to be explored. In order to realize the application of continuous lighting in plant factories, effects of LED red and continuous blue light (CL) on lettuce growth and nutrient absorption before harvesting were studied using ICP-AES technology in an environmentally controllable plant. Under the light intensity of 150 μmol·m-2·s-1, three kinds of red and blue light were set up: 2R∶1B (Q2∶1), 3R∶1B (Q3∶1) and 4R∶1B (Q4∶1), and two nitrogen forms: 80% nitrate nitrogen (N80%) and 100% nitrate nitrogen (N100%). The results showed that: The interaction between LED light quality and nutrient liquid nitrogen form had a significant effect on the dry shoot weight of hydroponic lettuce and had no significant effect on the fresh weight of the ground and the dry weight of the root before CL. There was no significant effect on the content and accumulation of N, C, P, K, Ca, Mg, Fe, Mn, Cu and Zn before CL. After CL, the interaction between light quality and nutrient liquid nitrogen form had significant effects on fresh root weight and dry root weight of hydroponic lettuce, and there was no significant difference in the effect of the fresh shoot and dry weight, only the content of N and P, N. The accumulation of P, Fe and Zn had a significant effect. CL had a significant effect on the biomass, nutrient elements content and accumulation of hydroponic lettuce. Comparing with pre-CL, the fresh shoot weight, fresh root weight, dry shoot weight and dry root weight increased significantly. The content of each nutrient element decreased in different degrees, and CL significantly reduced the contents of N, P, Fe and Zn, the content has no significant effect on the contents of C, K, Ca, Mg, Mn and Cu. CL significantly increased the accumulation of N, C, P, K, Ca, Mg, Fe, Mn, Cu, and Zn. In summary, LED light quality and nutrient solution nitrogen form treatment had a significant effect on the dry weight of the ground and had no significant effect on the content and accumulation of various nutrients before CL. The light quality of LED and nitrogen form of the nutrient solution had significant effects on the fresh and dry weight of root and had a significant effect on the content of N and P, the accumulation of N, P, Fe and Zn after CL. Compared with pre-CL, the fresh shoot weight, fresh root weight, dry shoot weight and dry root weight of hydroponic lettuce increased significantly after CL treatment. CL significantly reduced the contents of N, P, Fe and Zn, but N and C contents were significantly increased. The accumulation of P, K, Ca, Mg, Fe, Mn, Cu, and Zn were increased. In conclusion, the combination of cultivation light quality & nitrogen form (i. e. N80%Q4∶1) with pre-harvest continuous lighting by LED red and blue light is an optimal strategy for improving contents and accumulation of some kinds of nutrient elements in lettuce.