Chen Ren, Chen Yanqi, Lin Kunming, Ding Yiming, Liu Wenke, Wang Shurong
Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, School of Physics and Optoelectronic Engineering, Foshan University, Foshan 528225, China.
Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Int J Mol Sci. 2024 Dec 6;25(23):13116. doi: 10.3390/ijms252313116.
Alfalfa is a widely grown forage with a high crude protein content. Clarifying the interactions between light quality and nitrogen level on yield and nitrogen metabolism can purposely improve alfalfa productivity in plant factories with artificial light (PFAL). In this study, the growth, quality, and nitrogen metabolism of alfalfa grown in PFAL were investigated using three nitrate-nitrogen concentrations (10, 15, and 20 mM, labeled as N, N, and N) and continuous light (CL) with two light qualities (red-blue and red-blue-green light, labeled as RB-C and RBG-C). The results showed that the adaptation performance of alfalfa to nitrogen concentrations differed under red-blue and red-blue-green CL. Plant height, stem diameter, leaf area, yield, Chl a + b, Chl a, Chl b, crude protein contents, and NiR activity under the RB-CN treatment were significantly higher than RB-CN and RB-CN treatments. The RB-CN treatment showed morphological damage, such as plant dwarfing and leaf chlorosis, and physiological damage, including the accumulation of proline, HO, and MDA. However, the difference was that under red-blue-green CL, the leaf area, yield, and Chl a + b, carotenoid, nitrate, and glutamate contents under RBG-CN treatment were significantly higher than in the RBG-CN and RBG-CN treatments. Meanwhile, the contents of soluble sugar, starch, and cysteine were significantly lower. However, the crude protein content reached 21.15 mg·g. The fresh yield, dry yield, stomatal conductance, leaf area, plant height, stem diameter, crude protein, GS, and free amino acids of alfalfa were positively correlated with increased green light. In addition, with the increase in nitrogen concentration, photosynthetic capacity, NiR, and GOGAT activities increased, promoting growth and improving feeding value. The growth, yield, photosynthetic pigments, carbon, nitrogen substances, and enzyme activities of alfalfa were significantly affected by the interaction between nitrogen concentration and light quality, whereas leaf/stem ratio and DPPH had no effect. In conclusion, RB-CN15 and RBG-CN are suitable for the production of alfalfa in PFAL, and green light can increase the threshold for the nitrogen concentration adaptation of alfalfa.
紫花苜蓿是一种广泛种植的粗蛋白含量较高的饲料作物。阐明光质与氮水平对产量和氮代谢的相互作用，有助于在人工光植物工厂（PFAL）中有针对性地提高紫花苜蓿的生产力。在本研究中，采用三种硝态氮浓度（10、15和20 mM，分别标记为N₁、N₂和N₃）以及两种光质（红蓝光和红蓝光绿光，分别标记为RB-C和RBG-C）的连续光照（CL），对PFAL中生长的紫花苜蓿的生长、品质和氮代谢进行了研究。结果表明，在红蓝光和红蓝光绿光连续光照下，紫花苜蓿对氮浓度的适应表现有所不同。RB-CN₂处理下的株高、茎粗、叶面积、产量、叶绿素a + b、叶绿素a、叶绿素b、粗蛋白含量和硝酸还原酶（NiR）活性均显著高于RB-CN₁和RB-CN₃处理。RB-CN₃处理表现出形态损伤，如植株矮化和叶片黄化，以及生理损伤，包括脯氨酸、过氧化氢（HO）和丙二醛（MDA）的积累。然而，不同的是，在红蓝光绿光连续光照下，RBG-CN₂处理下的叶面积、产量以及叶绿素a + b、类胡萝卜素、硝酸盐和谷氨酸含量均显著高于RBG-CN₁和RBG-CN₃处理。同时，可溶性糖、淀粉和半胱氨酸的含量显著较低。然而，粗蛋白含量达到了21.15 mg·g⁻¹。紫花苜蓿的鲜产量、干产量、气孔导度、叶面积、株高、茎粗、粗蛋白、谷氨酰胺合成酶（GS）和游离氨基酸与绿光增加呈正相关。此外，随着氮浓度的增加，光合能力、NiR和谷氨酸合酶（GOGAT）活性增强，促进了生长并提高了饲用价值。氮浓度与光质的相互作用对紫花苜蓿的生长、产量、光合色素、碳氮物质和酶活性有显著影响，而叶/茎比和1,1-二苯基-2-三硝基苯肼（DPPH）不受影响。总之，RB-CN₁₅和RBG-CN₂适合在PFAL中生产紫花苜蓿，并且绿光可以提高紫花苜蓿对氮浓度的适应阈值。
