| Popis: |
Light-quality research indicates that narrowband lighting can regulate water relations in plants. However, few studies with light-emitting diodes (LEDs) have focused on evaluating the effects of light quality on root growth and morphology, which can significantly affect water uptake of plants. The objective of this study was to characterize shoot and root growth and morphology and their effect on single-leaf water-use-efficiency (WUE) of ‘Waldmann’s Green’ lettuce (Lactuca sativa L.) grown under different red:blue ratios. Five treatments were evaluated in this study: 100% red (0B); 7% blue + 93% red (7B); 26% blue + 74% red (26B); 66% blue + 34% red (66B); and 100% blue (100B). All treatments provided an average daily light integral of 11.5 mol m-2 d-1 using a 16-h photoperiod. Increasing blue light from 7B to 66B reduced shoot and root growth, and instantaneous leaf-level WUE. Leaf area and shoot fresh mass were highest under 0B, 7B, and 100B, and significantly decreased with increasing blue light up to 66B. Similarly, root dry mass, root volume, root surface area, and total root length were highest under 7B and decreased with increasing blue light. Overall, our findings suggest that when using red and blue LEDs, plants grown under higher blue light have growth and morphological responses that can negatively affect leaf-level WUE. |
