Plant factories - closed plant production systems (CPPS).

Abstract

Abstract A plant factory is an indoor, enclosed, crop cultivation system where the growing environment is precisely controlled to maximise production. This control over all aspects of plant growth includes light, temperature, humidity, air movement, carbon dioxide (CO2) and nutrition. This is largely achieved through soilless (hydroponic) cultivation techniques. The term plant factory has previously included high intensity production systems such as greenhouses reliant on natural light only or natural light supplemented with horticultural lighting, as well as those utilising only artificial lighting. More recently, 'plant factory' has come to represent a CPPS (closed plant production system) or termed PFAL (plant factory with artificial lighting) where no natural sunlight is required. Plant factories may also be referred to as 'indoor vertical farms' or 'indoor vertical cropping' in the USA and other countries, based on the multi-level nature of the systems which aim to maximise growing space. With a high level of environmental control, plant factories can produce vegetables two to four times faster than by typical outdoor cultivation (Luna-Maldonao et al., 2016), and with the use of vertical systems, optimise yields per unit of floor area. In addition to higher levels of production, plant factories are becoming increasingly sustainable as less water, fertilizers, pesticides and labour are consumed during cultivation (Hu et al., 2014).