Light environment control for reducing energy loss and increasing crop yield in plant factories

Abstract

Energy utilization for plant lighting is one of the primary constraints of the development of plant factories. Most researchers overlook the impact of energy attenuation during the propagation process on energy efficiency utilization, and the redistribution process of energy lacks corresponding theoretical guidance. Based on the expansion of Bouguer’s law, a new strategy of environmental control is proposed to solve this problem by interfering the form of energy propagation and redistributing the energy. Through the method of environment control, we establish two different environments (by changing surface reflectance): high-reflection environment and high-absorption environment (resembling an unbounded space). Near the leaf canopy in the high-reflection environment, the photosynthetic photon flux density (PPFD) and illumination intensity are 116.15 μmol∙m−2∙s−1 and 7069 lx, respectively. In contrast, in the high-absorption environment, the values are significantly lower: 30.59 μmol∙m−2∙s−1 for the PPFD and 1815 lx for the illumination intensity. The results of further plant growth experiments show that the average weight and leaf number growth of lettuces increased by 4.12 and 3.22 times, respectively, in high-reflection environment. The growing status of plants is also better in the high-reflection environment compared with the high-absorption environment. The strategy of environmental control provides a new direction to reduce energy loss and increase crop yield in plant factories.