Editorial: Advances and Trends in Development of Plant Factories

The plant factory is a facility that aids the steady production of high-quality vegetables all year round by artificially controlling the cultivation environment (e.g., light, temperature, humidity, carbon dioxide concentration, and culture solution), allowing growers to plan production. By controlling the internal environment, plant factories can produce vegetables about two to four times faster than by typical outdoor cultivation. In addition, as multiple cultivation shelves (a multi-shelf system) are used, the mass production of vegetables in a small space is facilitated. This research topic presents some new trends on intelligent measuring systems; environment controlled and optimization; flavonoids; phenylpropanoids, transcriptomes, and bacteria. Among some of the new findings on intelligent measuring systems, Chen et al. developed an automated measurement system to measure and record the plant weight during plant growth in plant factory. They found that plant weights measured by the weight measurement device are highly correlated with the weights estimated by the stereo-vision imaging system. Moriyuki and Fukuda devised a novel high-throughput diagnosis system using the measurement of chlorophyll fluorescence forming an image of 7200 seedlings acquired by a CCD camera and an automatic transferring machine. They used machine learning in order to extract biological indices and predict plant growth. Previously, Hashimoto et al. (2001) applied an intelligent control system consisting of a decision system based on neuronal networks and genetic algorithms to optimize the growth of hydroponic tomato plants during the seedling stage. Hwang et al. (2014) also proposed a plant factory automatic control system to collect crop image information (illuminance, temperature, humidity, EC, pH, and CO2) and provided crop environment control and service suitable for crop growth step (crop shape, size, color, and length). Related to environment controlled and optimization, Zheng et al. explored the effects of different density treatments on potato spatial distribution and yield in spring and fall. They concluded that increased density significantly increased potato yield, but the degree of influence associated with different growing seasons differed slightly. In Japan, there were 165 plant factories with artificial lighting (Kozai et al., 2015). Wang et al. added an air exchanger for cooling in plant production systems with artificial light (PPAL). They found that using air exchanger to introduce outdoor cold air is as an effective way to reduce electric-energy consumption with little effects on plant growth in a PPAL. Besides, the cultivation methods in a plant factory with artificial lighting (PFLA) were studied by Zhang et …