Control of growth and flowering of chrysanthemum (Dendranthema x grandiflorum Kitam.) using day length extension and Red Light Night Break

Million Haile Belay,Amsalu Gobena Roro,Hussien Mohammed Beshir,Meseret Tesema Terfa

doi:10.1590/2447-536x.v27i3.2338

Abstract

Abstract In tropical areas, since the day length (DL) is shorter than the critical DL for chrysanthemum (Dendranthema x grandiflorum Kitam.), chrysanthemum flowers before reaching the required stem length (SL) for cut flower. Two experiments were conducted with the aim of determining critical DL for vegetative growth of chrysanthemum genotype; to attain a required SL and promote vegetative growth of chrysanthemum using night break (NB) with red light for spray type of chrysanthemum. In the first experiment, DL was extended by one, two, and three hours using white fluorescent light (WL) after sunset. In the second experiment, red light (RL) was applied at the middle of the night for 15, 30, or 45 minutes to break the night. The experiments were laid out in completely randomized design with four replications. The results indicated DL extension with WL and RL night breaks had significant effect on vegetative characters and biomass yield. Similarly, flower bud initiation, coloring and blooming were significantly affected. NB using RL had a significant effect on flower diameter. The three hours DL extension (12+3 hours) totally inhibited flowering of chrysanthemum genotype, which can be considered a critical DL for Hawa1. NB with RL for 15, 30, or 45 minutes effectively inhibited flowering of chrysanthemum. In conclusion, breaking the night with RL at the middle of the night for 15 minutes with small amount of intensity (9.42 µmolm-2s-1) is enough to inhibit flowering and promote stem elongation of chrysanthemum Hawa1.

Highlights

IntroductionThe length of the light phase, the photoperiod, determines flowering time
In most plant species, the length of the light phase, the photoperiod, determines flowering time
Previous report indicated that Red and Far-Red lights, which are absorbed by the phytochrome system, are important in controlling photomorphogenesis and flowering (Legris et al, 2019)

Summary

Introduction

The length of the light phase, the photoperiod, determines flowering time. CONTROL OF GROWTH AND FLOWERING OF CHRYSANTHEMUM (DENDRANTHEMA X GRANDIFLORUM KITAM.) USING DAY LENGTH EXTENSION AND RED LIGHT NIGHT BREAK ornamental plant, a typical SD plant, which flowers when nights are longer than a critical minimum length. Light treatment demonstration on different plant species revealed that night breaking with red light was shown to be the most effective in inhibiting flowering; and the effect was reversed when treated with FR-light (Zhang and Runkle, 2019). Red to far-red light-absorbing phytochromes have long been considered important photoperiodic photoreceptors. Recent molecular genetic investigations have revealed that phytochromes are essential for photoperiodic flowering in most short day plants species (Park and Jeong, 2019). Previous report indicated that Red and Far-Red lights, which are absorbed by the phytochrome system, are important in controlling photomorphogenesis and flowering (Legris et al, 2019). Phytochromes are a photoreceptor pigment that if found in plants regulate plant development, physiology, and metabolism, based on circadian, seasonal, and positional information (Lymperopoulos et al, 2018)

Methods

Results

Discussion

Conclusion