The nitrogen content of nutrient solution and light intensity are two crucial factors affecting the yield and quality of controlled environment hydroponic vegetables. In this study, Purple Bok Choy ( Brassica rapa var. Chinensis) was evaluated in a two-factor experiment with five levels of light intensity and five levels of nitrogen concentration. The plants were harvested on the 35th day after planting and different parameters such as shoot fresh weight, root fresh weight, anthocyanin, and soluble sugar were measured as representatives of yield and quality. This paper investigated the effects of different light/nitrogen combinations on the yield and quality of Purple Bok Choy, and established an optimal model coupled with yield and quality indicators. The result reveals that the light intensity and nitrogen concentration have a strong synergistic interaction on shoot fresh weight, root fresh weight, anthocyanin, and soluble sugar of Purple Bok Choy. A combination of light/nitrogen could be found to achieve the common improvement for the indicators with a similar change trend. This work gives valuable insights into the combinational regulation of nitrogen concentration and light intensity and provides a new idea for the comprehensive improvement of production yield and quality.

中文翻译：

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光照强度和氮浓度与产量和质量耦合的优化模型

营养液的含氮量和光照强度是影响可控环境水培蔬菜产量和品质的两个关键因素。在这项研究中，紫白菜 (Brassica rapa var. Chinensis) 在五级光强度和五级氮浓度的双因素实验中进行了评估。在种植后第 35 天收获植物，并测量不同的参数，如嫩枝鲜重、根鲜重、花青素和可溶性糖，作为产量和质量的代表。研究了不同光/氮组合对紫白菜产量和品质的影响，建立了产量和品质指标耦合的优化模型。结果表明，光照强度和氮浓度对紫白菜地上部鲜重、根部鲜重、花青素和可溶性糖具有较强的协同作用。可以找到光/氮的组合来实现具有相似变化趋势的指标的共同改进。该工作为氮浓度和光照强度的联合调控提供了有价值的见解，为综合提高产量和质量提供了新的思路。