不同光强的LED白光与红蓝光对生菜生长及营养元素含量的影响

在人工光植物工厂中研究了不同光强的LED白光和红蓝光对营养液水培生菜生长、营养元素含量和累积量的影响。试验设置白光（WL）和红蓝光（RB）两个光质处理，光周期为16/8 h，分别设定三个光强：150（WL150、RB150）、200（WL200、RB200）和250（WL250、RB250）μmol·m^-2·s^-1，其中红蓝光光强比为4∶1,光暗周期16/8 h。结果表明，光强增加有促进生菜生长作用，随光强增加生菜地上部干、鲜重明显增加，WL200和WL250处理下生菜地上部干重比WL150分别提高了24.6%和49.7%。与红蓝光相比，白光显著提高生菜叶面积和地上部生物量。红蓝光提高了生菜叶片中大中量元素（N、P、Ca、Mg）和微量元素（Mn、Zn）的含量，白光则提高了K的含量，光质对C、Fe和Cu含量无明显影响。白光或红蓝光下不同光强对生菜叶片营养元素含量的影响并没有表现出明显的规律，只是红蓝光在200 μmol·m^-2·s^-1光强下多种营养元素（N、P、Ca、Mg、Mn、Cu和Zn）含量到达最大。在白光200 μmol·m^-2·s^-1的光强下，P、K、Ca、Mg、Fe、Mn、Cu和Zn的累积量最大，而在红蓝光250 μmol·m^-2·s^-1的光强下，10种营养元素的累积量均最大。相同光强下，红蓝光有利于生菜体内N、P、Ca、Mg、Mn和Zn含量的提高，而白光则更有利于C、N、P、K、Mg和Fe等的累积。因此白光处理更有利于促进生菜生长，并提高生菜体内N、C、P、K、Mg和Fe的累积量，其累积量的提高主要是由较高的生物量决定的。

Effects of White vs. Red/Blue LED Light of Different Intensity on the Growth and Nutrient Element Content of Hydroponic Lettuce

In this study, the effects of white vs. red/blue LED light of different intensity on the growth and nutrient element content as well as accumulation of hydroponic lettuce were studied using ICP-AES analysis technology in a closed plant factory. White light (WL) and the combination of red and blue light (RB) at different intensities including 150（WL150, RB150）, 200（WL200, RB200）, 250（WL250, RB250）μmol·m^-2·s^-1were conducted in the experiment. Red/blue ratio was 4∶1, and photoperiod was 16/8 h. The results showed that both shoot fresh weight and shoot dry weight increased with the increase of light intensity. And the shoot dry weight under WL200 and WL250 was 24.6% and 49.7% higher than that of WL150, respectively. Compared with RB, WL significantly increased leaf area and biomass of lettuce. RB increased the contents of large and medium elements (N, P, Ca, Mg) and trace elements (Mn, Zn) in lettuce leaves, while WL increased K content. Light quality had no significant effect on C, Fe and Cu contents. The content of nutrient elements in lettuce had no obvious regularity response to light intensity under WL or RB. The contents of various nutrient elements (N, P, Ca, Mg, Mn, Cu, and Zn) were the highest at 200 μmol·m^-2·s^-1under red and blue light. Under WL, the accumulations of P, K, Ca, Mg, Fe, Mn, Cu, and Zn were the highest at 200 μmol·m^-2·s^-1, while the accumulations of ten nutrient elements were the highest at 250 μmol·m^-2·s^-1under RB. Under the same light intensity, RB was beneficial for the increase of N, P, Ca, Mg, Mn, and Zn contents in lettuce, while WL was more conducive for the accumulations of N, C, P, K, Mg, and Fe. In conclusion, WL could promote the growth of lettuce and increase the accumulation of N, C, P, K, Mg, and Fe in lettuce, which was mainly determined by higher biomass.