Intermittent Supplementation with Far-Red Light Accelerates Leaf and Bud Development and Increases Yield in Lettuce

Area of Science:

• Plant Science
• Controlled Environment Agriculture
• Photobiology

Background:

• Far-red light supplementation can increase crop yield in controlled environments by inducing shade avoidance syndrome.
• Intermittent application of far-red light may offer superior yield enhancement compared to constant exposure.

Purpose of the Study:

• To investigate the impact of varying far-red light intensities and intermittent exposure durations on lettuce growth in plant factories.
• To determine the optimal intermittent far-red light strategy for maximizing lettuce yield and quality.

Main Methods:

• Lettuce (Lactuca sativa) was grown in plant factories under controlled conditions with constant red light and varying intermittent far-red light treatments (5, 15, 30, 45 min intervals).
• Phytohormone content, gene expression (hormone metabolism and transport), and transcriptome analysis were conducted.
• Weighted Gene Co-expression Network Analysis and dynamic expression analysis were employed.

Main Results:

• A 30-minute interval of intermittent far-red light supplementation increased lettuce yield by 11.7% and the number of leaves and buds by 2.66 compared to constant far-red light.
• Intermittent far-red light enhanced the overall effectiveness of far-red light treatments, influencing gene expression related to signaling and hormone metabolism.
• Optimal rhythmic gene expression for far-red photoreception and hormone pathways occurred under 30-minute intermittent far-red light.

Conclusions:

• Intermittent far-red light supplementation, particularly at 30-minute intervals, is highly effective for enhancing lettuce growth and yield in plant factories.
• This light strategy optimizes far-red light signaling, hormone metabolism, and transport, leading to accelerated plant development.
• The findings provide a basis for optimizing lighting strategies in controlled environment agriculture for improved crop production.