Effect of supplemental lighting on primary gas exchanges of Chrysanthemum × morifolium Ramat cultivar White Reagan

Abstract

Flower greenhouse production is reduced in winter, which is due to the short photoperiod and low light levels. Studies indicate that LEDs could increase the quality and yield of ornamental crops. However, there is very little research about LED and HPS effects on chrysanthemums during long day (LD) and short day (SD). Plants were grown in the research greenhouse and growth chambers at the University of Guelph. Plants were subjected to a 16h photoperiod (LD) and a subsequent 12h photoperiod (SD). Four different light treatments were compared: 1) Natural light (Amb), 2) Amb supplemented with Red/white LEDs, 3) Amb supplemented with Red/blue LEDs and 4) Amb supplemented with HPS. Plant height, leaf area, dry matter of different parts, SPAD reading, and leaf and whole-plant level photosynthesis, respiration, transpiration, water use efficiency and daily carbon gain during both long day and short day periods were measured. We concluded that chrysanthemums showed different response to light spectrum quality between LD and SD at the leaf level but not the whole plant level.