Lanoue Jason, St Louis Sarah, Little Celeste, Hao Xiuming
Harrow Research and Development Centre, Agriculture & Agri-Food Canada, Harrow, ON, Canada.
Front Plant Sci. 2022 Sep 30;13:983222. doi: 10.3389/fpls.2022.983222. eCollection 2022.
Microgreens represent a fast growing segment of the edible greens industry. They are prized for their colour, texture, and flavour. Compared to their mature counterparts, microgreens have much higher antioxidant and nutrient content categorizing them as a functional food. However, current production practices in plant factories with artificial light are energy intensive. Specifically, the lack of sunlight within the indoor structure means all of the light must be provided energy consuming light fixtures, which is energy intensive and costly. Plant growth is usually increased with the total amount of light provided to the plants - daily light integral (DLI). Long photoperiods of low intensity lighting (greater than 18h) providing the desired/target DLI can reduce the capital costs for light fixtures and electricity costs. This is achieved by moving the electricity use from peak daytime hours (high price) to off-peak hours (low price) during the night in regions with time-based pricing scheme and lowering the electricity use for air conditioning, if plant growth is not compromised. However, lighting with photoperiods longer than tolerance thresholds (species/cultivar specific) usually leads to plant stress/damage. Therefore, we investigated the effects of continuous 24h white light (CL) at two DLIs (~14 and 21 mol m d) on plant growth, yield, and antioxidant content on 4 types of microgreens - amaranth, collard greens, green basil, and purple basil to see if it compromises microgreen production. It was found that amaranth and green basil had larger fresh biomass when grown under CL compared to 16h when the DLIs were the same. In addition, purple basil had higher biomass at higher DLI, but was unaffected by photoperiods. Plants grown under the CL treatments had higher energy-use-efficiencies for lighting (10-42%) than plants grown under the 16h photoperiods at the same DLI. Notably, the electricity cost per unit of fresh biomass ($ g) was reduced (8-38%) in all microgreens studied when plants were grown under CL lighting at the same DLIs. Amaranth and collard greens also had higher antioxidant content. Taken together, growing microgreens under CL can reduce electricity costs and increase yield while maintaining or improving nutritional content.
微型蔬菜是可食用蔬菜产业中快速增长的一个部分。它们因其颜色、质地和风味而备受珍视。与成熟的同类蔬菜相比，微型蔬菜具有更高的抗氧化剂和营养成分含量，因此被归类为功能性食品。然而，目前人工光照植物工厂的生产方式能源消耗大。具体而言，室内结构缺乏阳光意味着所有的光照都必须由耗能的灯具提供，这既耗能又昂贵。植物的生长通常会随着提供给植物的总光照量——日光照积分（DLI）的增加而增加。低强度光照（大于18小时）的长光周期提供所需的/目标DLI可以降低灯具的资本成本和电力成本。这是通过在有分时电价方案的地区，将用电时间从白天的高峰时段（高价）转移到夜间的非高峰时段（低价）来实现的，并且如果不影响植物生长，还可以降低空调的用电量。然而，光周期长于耐受阈值（因物种/品种而异）的光照通常会导致植物应激/受损。因此，我们研究了两种DLI（约14和21摩尔·米²·天）下的连续24小时白光（CL）对苋菜、羽衣甘蓝、绿罗勒和紫罗勒这4种微型蔬菜的植物生长、产量和抗氧化剂含量的影响，以确定其是否会影响微型蔬菜的生产。结果发现，在相同DLI下，苋菜和绿罗勒在CL光照下生长时的鲜生物量比16小时光照时更大。此外，紫罗勒在较高DLI时生物量更高，但不受光周期的影响。与在相同DLI下16小时光周期生长的植物相比，CL处理下生长的植物具有更高的光照能源利用效率（10 - 42%）。值得注意的是，当植物在相同DLI下的CL光照下生长时，所有研究的微型蔬菜每单位鲜生物量的电费（美元/克）都降低了（8 - 38%）。苋菜和羽衣甘蓝的抗氧化剂含量也更高。综上所述，在CL光照下种植微型蔬菜可以降低电费并提高产量，同时保持或改善营养成分。
