Light Environmental Management for Artificial Protected Horticulture

Abstract

Light is a vital environmental factor that affects plant growth and development by acting on plants not only as the sole energy source of photosynthesis, but also as the kind of external signal. Light requirements of plants are subjected to species, cultivar, growth and developmental stages of plant, environmental conditions and manipulation target of yield & quality. Therefore, detailed studies on light formula (LF) based on physiological requirement are urgently needed for getting high yield and good quality in plants. With the development of semiconductor solid light sources, light-emitting diodes (LEDs), light quality physiology and light formula in plants have been gradually and extensively conducted worldwide by taking advantage of LED providing precise light spectrum and close illumination. LF defined as optimized and integrated assembly of spectral component emitting from light sources (particularly LEDs) that is suitable for plant productivity and nutritional quality formation. Based on published literatures, red, blue, and compound white light are macro-necessary light spectrum, and purple, green, yellow and orange light are micro-beneficial light spectrum, while far-red light and ultraviolet light are beneficial light spectrum. However, other light spectrum except photosynthetic active radiation, far-red and ultraviolet light is invalid for plant cultivation. Our hypothesis is that one or two kinds of necessary light quality, special micro-beneficial and beneficial light quality can make up a light formula for a kind of plant during certain period and certain environmental conditions. LF is a crucial scientific issue that should be established for protected cultivation plants with artificial light or plants that needed supplemental light. More importantly, LF is an important part of light environment management strategy (LEMS), referring to management of light intensity, LF and photoperiod. LEMS should be established for plant cultivation with artificial light sources. In this project, the application of LF and LEMS will be used in the plant factory for the advantages of entire artificial light source, cultivation with nutrient solution and intelligentized environmental control. Furthermore, vegetables, particularly leafy vegetables, will be preferentially used for the project. To sum up, the study will focus on LF which will provide technique parameters for potential efficiency (high yield and good quality) during plant growth and development.