交替光谱辐照对叶用莴苣营养元素水平的影响

在人工光型植物工厂中采用深液流水培法栽培叶用莴苣，依托光谱时空分布可精准调控的智能LED光源系统，应用电感耦合等离子体原子发射光谱技术（ICP-AES），研究了5 min，10 min，15 min，30 min，60 min，2 h，4 h和8 h等不同间隔的红、蓝光谱交替照射对叶用莴苣中K，P，Ca，Mg，Fe，Mn，Zn和Cu等8种营养元素吸收和累积的影响。结果表明：(1) 与同时照射模式相比，所有的交替光谱处理均显著提高了叶用莴苣地上部生物量，其中鲜重提高幅度约为18.6%~67.4%，干重提高幅度约为5.1%~88.0%；所有的交替红蓝光谱照射下叶用莴苣体内Mg，Fe和Zn元素的植株累积量均得到显著（p＜0.05）地提高；所有的红蓝交替光谱辐射处理均不同程度地降低了叶用莴苣植株中Ca元素含量。(2) 间隔为5 min的红蓝交替光谱辐射下莴苣植株Fe元素含量显著高于其他任意处理，较其他处理增加了38.87%~85.37%，高频次的红蓝光切换照射刺激了叶用莴苣植株对Fe元素的吸收。(3) 红蓝交替光谱辐射有利于提高叶用莴苣的能量利用效率，与红蓝同时供光的RB处理相比，所有交替处理均显著提高了叶用莴苣的光、电能利用率，提高幅度分别约为34.3%~87.5%和34.6%~87.9%；其中，间隔为4 h的红蓝交替光谱辐射下叶用莴苣植株的光、电能利用率均最大，分别为6.13%和2.01%，除间隔为5和10 min的红蓝交替光谱辐射处理外的其他交替光谱处理下的植株光、电能利用率均与处理间最大值无显著性差异。(4) 叶用莴苣对K和Mg两种元素的吸收在红蓝光交替间隔为10 min，15 min，60 min及4 h等多个处理下呈现拮抗现象。(5) R/B(30 m)处理下叶用莴苣中P，Ca，Fe和Mn等四种元素的含量水平均呈现处理间最低水平，其中P和Ca元素含量水平显著低于对照。

Effects of Alternating Light Spectrum on the Mineral Element Level of Lettuce

Lettuce (Lactuca sativa) was cultured in a completely enclosed plant factory and irradiated with an intelligent LED light system with accurate regulation of spectral space-time distribution. Absorption and content of eight mineral elements such as K, P, Ca, Mg, Fe, Mn, Zn and Cu in Lactuca sativa exposed to alternating red and blue light spectrum with different alternating intervals were studied by ICP-AES technology. The results showed that: (1) Compared with concurrent red and blue light spectrum, all the alternating spectrum treatments increased shoot biomass of lettuce, the increasing range of fresh weight and dry weight was respectively 18.6%~67.4% and 5.1%~88.0%. All the alternating spectrum treatments significantly increased the accumulation of Mg，Fe and Zn in the lettuce plant (p＜0.05); all the alternating spectrum treatments decreased the content of Ca in lettuce to different extents. (2) Fe content in lettuce subjected to R/B(5 m) was significantly higher than any other treatment, increasing by 38.87%~85.37% compared with the other treatments. Alternating red and blue light spectrum with high alternating frequency seemed to stimulate Fe uptake by lettuce plants. (3) Alternating red and blue light spectrum enhanced the use efficiency of light photons and electricity by lettuce. Compared with RB, all alternating treatments significantly improved the light and electric use efficiency of leaf lettuce by about 34.3%~87.5% and 34.6%~87.9%; Among them, the light and electric use efficiency of leaf lettuce were both the largest under the alternating treatment with an interval of 4 h, which were 6.13% and 2.01% respectively. Except for the alternating treatments with the intervals of 5 m and 10 m, no significant difference existed in the light and electric use efficiency of plants among the alternating spectrum treatments. (4) The absorption of K and Mg by lettuce showed antagonism under the alternating intervals of 10m, 15 m, 60 m and 4 h. (5) The contents of P，Ca，Fe and Mn in lettuce treated with R/B(30 m) showed the lowest level among treatments, and the contents of P and Ca were significantly lower than the control.