Nelson Jacob A, Bugbee Bruce
Crop Physiology Laboratory, Department of Plant Soils and Climate, Utah State University, Logan, Utah, United States of America.
PLoS One. 2014 Jun 6;9(6):e99010. doi: 10.1371/journal.pone.0099010. eCollection 2014.
Lighting technologies for plant growth are improving rapidly, providing numerous options for supplemental lighting in greenhouses. Here we report the photosynthetic (400-700 nm) photon efficiency and photon distribution pattern of two double-ended HPS fixtures, five mogul-base HPS fixtures, ten LED fixtures, three ceramic metal halide fixtures, and two fluorescent fixtures. The two most efficient LED and the two most efficient double-ended HPS fixtures had nearly identical efficiencies at 1.66 to 1.70 micromoles per joule. These four fixtures represent a dramatic improvement over the 1.02 micromoles per joule efficiency of the mogul-base HPS fixtures that are in common use. The best ceramic metal halide and fluorescent fixtures had efficiencies of 1.46 and 0.95 micromoles per joule, respectively. We also calculated the initial capital cost of fixtures per photon delivered and determined that LED fixtures cost five to ten times more than HPS fixtures. The five-year electric plus fixture cost per mole of photons is thus 2.3 times higher for LED fixtures, due to high capital costs. Compared to electric costs, our analysis indicates that the long-term maintenance costs are small for both technologies. If widely spaced benches are a necessary part of a production system, the unique ability of LED fixtures to efficiently focus photons on specific areas can be used to improve the photon capture by plant canopies. Our analysis demonstrates, however, that the cost per photon delivered is higher in these systems, regardless of fixture category. The lowest lighting system costs are realized when an efficient fixture is coupled with effective canopy photon capture.
用于植物生长的照明技术正在迅速改进，为温室中的补光提供了众多选择。在此，我们报告了两种双头高压钠灯灯具、五种大型螺口灯座高压钠灯灯具、十种LED灯具、三种陶瓷金属卤化物灯灯具和两种荧光灯灯具的光合（400 - 700纳米）光子效率及光子分布模式。效率最高的两款LED灯具和两款双头高压钠灯灯具的效率几乎相同，为每焦耳1.66至1.70微摩尔。这四种灯具相比常用的大型螺口灯座高压钠灯灯具每焦耳1.02微摩尔的效率有了显著提高。最好的陶瓷金属卤化物灯灯具和荧光灯灯具的效率分别为每焦耳1.46和0.95微摩尔。我们还计算了每提供一个光子的灯具初始资本成本，发现LED灯具的成本比高压钠灯灯具高五到十倍。由于资本成本高，LED灯具每摩尔光子的五年电费加灯具成本因此比高压钠灯灯具高2.3倍。与电费相比，我们的分析表明两种技术的长期维护成本都较小。如果宽间距种植台是生产系统的必要组成部分，LED灯具将光子有效聚焦在特定区域的独特能力可用于提高植物冠层对光子的捕获。然而，我们的分析表明，在这些系统中，无论灯具类别如何，每提供一个光子的成本都更高。当高效灯具与有效的冠层光子捕获相结合时，照明系统成本最低。
