The application of artificial light to improve crop production in greenhouses is widely used in the horticultural sector. In this study, we evaluated the impact of light quality on sweet pepper plants’ physiology during a period of water deficit. Pepper plants were cultivated in a climate chamber and exposed to three different light regimes; (compact fluorescent lamps [CFL], continuous intensity from light emitting diodes [LED] [LEDcont] and bell-like shape illumination schedule from LEDs [LEDday]). The effect of temporary water shortage under these light treatments on plant height, chlorophyll and proline concentration, the maximum efficiency of photosystem II (F_v/F_m), the electron transport rate (ETR), and the non-photochemical quenching (NPQ), were studied. In general, plants exposed to CFL showed higher growth rates as compared to those exposed to LED under well-watered conditions. However, the lighting source did not induce significant effects on plant growth and chlorophyll concentration during water deficit, even though proline concentration was higher in plants exposed to CFL and to drought when compared to those exposed to LEDcont and LEDday. LED radiation led to a higher ETR and an early onset of NPQ under water deficit, suggesting an activation of the cyclic electron transport. As outcome, plants grown under LEDcont showed the highest photochemical performance. Overall, the results suggest that pepper plants grown under CFL radiation perform better, even under water deficit, possibly due to the more balanced light spectrum.

中文翻译：

---

干旱对甜椒植株叶片光生理的影响

园艺领域广泛使用人造光来改善温室中的农作物产量。在这项研究中，我们评估了缺水时期光质对甜椒植物生理的影响。辣椒植物在气候箱中种植，并暴露于三种不同的光照条件下。（紧凑型荧光灯[ CFL ]，连续的强度从发光二极管[LED] [ LEDcont ]和铃状来自LED照明形状时间表[ LEDday ]）。在这些光照条件下临时缺水对植物高度，叶绿素和脯氨酸浓度，光系统II的最大效率（F _v / F _m），电子传输速率（ETR）和非光化学猝灭（NPQ）。通常，与暴露于CFL的植物相比，在良好灌溉条件下暴露于LED的植物， 生长速率更高。然而，尽管与暴露于LEDcont和LEDday的植物相比，暴露于CFL和干旱的植物中脯氨酸的浓度更高，但光源在缺水期间并未对植物的生长和叶绿素浓度产生明显影响 。LED辐射导致较高的ETR和缺水情况下NPQ的早期发作，表明激活了循环电子传输。结果，在LEDcont下生长的植物表现出最高的光化学性能。总体而言，结果表明，在CFL辐射下生长的辣椒植物即使在缺水的情况下也表现更好，这可能是由于光谱更加平衡所致。