Selective LED Lighting for Leaf-and-Stem Vegetable Growth Control
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Solution Overview
Problem
Conventional lighting devices for plant cultivation irradiate entire plants with different colors of light, leading to inefficient light usage and increased production costs, as non-essential parts of the plant are also illuminated, which affects the commercial value of leaf-and-stem vegetables like leaf lettuce by promoting stem growth over leaf growth.
Innovation Solution
A method and light source device that selectively irradiate leaf-and-stem vegetables with a high blue light ratio to inhibit stem growth and a high red light ratio to accelerate leaf growth, using LEDs or organic ELs, during specific growth periods, targeting only the stems and leaves respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the entire plant is irradiated with different colors of light from multiple light emission zones, then the plant receives comprehensive light stimulation for growth, but the light irradiation becomes inefficient and power is wasted on parts that do not require irradiation
Solution Approach 1:
The light emission unit is divided into multiple light emission zones (central zone, second zone, third zone, fourth zone) with different light colors, and each zone is selectively activated based on plant growth stage and specific plant part requirements, avoiding unnecessary irradiation to certain areas
Solution Approach 2:
Different light colors (red, blue, green, multiple colors) are applied to different light emission zones corresponding to different plant parts or growth stages, providing localized light quality matching the specific needs of plant tissues at different locations and developmental phases
2Productivity
If light is irradiated on the entire plant including stems during all growth periods, then the plant receives continuous light stimulation, but the stem grows excessively long reducing the commercial value of leaf-and-stem vegetables
Solution Approach 1:
The lighting system applies different light colors at different growth periods: blue light is used during the initial growth period to inhibit stem elongation, while red light is applied during later stages to promote leaf expansion, creating a periodic lighting regimen that optimizes both stem and leaf development at appropriate times
Solution Approach 2:
The spectral composition parameters of the light are changed according to growth stage and target tissue: blue light (shorter wavelength) is used to suppress stem elongation, while red light (longer wavelength) is used to promote leaf photosynthesis and expansion, dynamically adjusting light parameters to achieve desired growth outcomes
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the commercial value of leaf-and-stem vegetables by prioritizing leaf growth, reducing energy consumption, and extending the lifespan of the light sources, thereby increasing the harvested amount and improving the appearance and value of the vegetables.
Implementation Method 1
a stem growth-inhibiting light source irradiates stems with light having a blue component light at high ratio, which inhibits the growth of stems
Implementation Method 2
a leaf growth-accelerating light source irradiates the leaves with light having a red component light at high ratio, which accelerates the growth of the leaves
Data Source
AI summary
A method for raising leaf-and-stem vegetables and a light source device used in the method, which can make production cost of leaf-and-stem vegetables reduced and commercial value thereof enhanced by irradiating parts of leaf-and-stem vegetable with a light optimum therefor. The method for raising leaf-and-stem vegetables by irradiating the vegetables with light, includes a stem growth-inhibiting light source irradiating tops of the stems with light having a blue component light at high ratio, which inhibits the growth of stems, at least during an initial growth period when the stems and leaves become distinguishable from each other.