Abstract：
The spectral composition of some light-emitting diodes (LEDs) reportedly results in higher crop yield, prevents wilting, and reduces thermal damage to plants. The use of LEDs for postharvest storage and shelf-life extension has been limited, but the potential of this technology will allow for greater applications in horticulture and the food industry. In this experiment, \'Winterbor\' kale (Brassica oleracea) and \'Melody\' spinach (Spinacia oleracea) plants were measured for the light compensation point and stomatal response under 14 different wavelengths of light ranging from 405 to 661 nm. Data collected from these measurements were used to select two different wavelengths of LEDs and determine the proper irradiance levels for an LED irradiance storage test on spinach and kale. Treatments comprising blue, red, and amber lights were effective at increasing the stomatal opening, while the green light resulted in reduced stomatal opening. For spinach, the light response curve showed that light compensation points at 500 nm and 560 nm were 65.3 and 64.7 μmol m-2 s-1, respectively. For kale, the light compensation points at 500 nm and 560 nm were 50.8 and 44.1 μmol m-2 s-1, respectively. For the storage test experiment at room temperature, kale and spinach were stored under four different treatments: dark treatment (control), standard white fluorescent light, 500 nm, and 560 nm LED wavelengths. For spinach, the moisture content was 70.1% at 560 nm and 53.7% for dark, moisture losses of 41.5% under the 560-nm treatment and 52.0% for the dark treatment. The fresh basis moisture content was 74.6% at 560 nm and 59.3% in the dark. Moisture loss under the 560 nm treatment was 39.6% while the dark treatment had a 54.0% moisture loss. A visual assessment scale was monitored, 560 nm resulted in the top visual quality for kale compared to the other treatments with the lowest visual quality under the dark treatment at day 4. For spinach, the visual quality for 560 nm treatment was statistically the standard white fluorescent light and 500 nm, with poor-quality product occurring by day 4 and the lowest-quality product occurring at day 5. The LED treatments improved the shelf life of spinach and kale, likely as a result of stomatal aperture closure, photosynthetic rate near the light compensation point and stability of the atmospheric moisture content. This study provides valuable information on the extension of the shelf life of leafy greens during storage. Reducing fresh produce waste in grocery stores will increase revenue, thereby benefiting the Canadian economy while providing social and environmental benefits that entail increased food security and reduced food waste.
摘要：
据报道，一些发光二极管（LED）的光谱组成导致作物产量提高，防止枯萎，并减少对植物的热损伤。使用LED进行采后储存和延长保质期已经受到限制，但是这项技术的潜力将允许在园艺和食品工业中得到更大的应用。在这个实验中,在405至661nm的14种不同波长的光下，测量了\'Winterbor\'羽衣甘蓝（Brassicaoleracea）和\'Melody\'菠菜（Spinaciaoleracea）植物的光补偿点和气孔响应。从这些测量中收集的数据用于选择两种不同波长的LED,并确定用于菠菜和羽衣甘蓝上的LED辐照度储存测试的适当辐照度水平。治疗包括蓝色，红色,琥珀色的光有效地增加了气孔的开口，而绿灯导致气孔开口减少。对于菠菜，光响应曲线显示，在500nm和560nm处的光补偿点分别为65.3和64.7μmolm-2s-1。对于羽衣甘蓝，在500nm和560nm处的光补偿点分别为50.8和44.1μmolm-2s-1。对于室温下的储存测试实验，羽衣甘蓝和菠菜在四种不同的处理下储存：深色处理（对照），标准白色荧光灯，500nm,和560纳米LED波长。对于菠菜，水分含量在560纳米为70.1%，黑暗为53.7%，560nm处理下的水分损失为41.5%,暗色处理下的水分损失为52.0%。新鲜的基础水分含量在560nm为74.6%,在黑暗中为59.3%。560nm处理下的水分损失为39.6%,而深色处理具有54.0%的水分损失。监测视觉评估量表，与在第4天黑暗处理下具有最低视觉质量的其他处理相比,560nm导致羽衣甘蓝的最高视觉质量。对于菠菜，560nm处理的视觉质量在统计学上是标准的白色荧光和500nm,在第4天出现质量差的产品，在第5天出现质量最低的产品。LED处理改善了菠菜和羽衣甘蓝的保质期，可能是气孔孔闭合的结果，光补偿点附近的光合速率和大气水分含量的稳定性。这项研究为延长绿叶蔬菜在储存过程中的保质期提供了有价值的信息。减少杂货店的新鲜农产品废物将增加收入，从而使加拿大经济受益，同时提供社会和环境效益，从而增加粮食安全和减少食物浪费。
