“Finish of day” far-red gentle will increase stem size in chrysanthemum


Within the final decade, curiosity in LED lighting amongst chrysanthemum growers has elevated significantly. Initially in hybrid lighting methods with LED lighting supplementing the present HPS lamps, however not too long ago additionally in full-LED methods. There are nonetheless many questions on which gentle spectrum is probably the most suited to chrysanthemum, particularly in terms of realizing the specified stem size.

Growers concern that, particularly in winter, chrysanthemums grown beneath LED lighting stay too brief at low cultivation temperatures. Subsequently, analysis was carried out on the enterprise unit Greenhouse Horticulture of Wageningen College & Analysis into the impact of spectral composition of the sunshine on chrysanthemums. The analysis targeted on the choices to regulate stem elongation with far-red gentle.

Good high quality flowers
In Autumn 2021, 4 chrysanthemum varieties had been grown beneath full LED supplementing the out there daylight. Winter circumstances had been simulated throughout the trial by permitting the share of daylight within the whole gentle sum to be 22% and the share of LED gentle in 78%. Outcomes confirmed that chrysanthemums will be grown nicely beneath full LED. All varieties (Magnum, Baltica, Stylish and Pina colada) reached the business stem weight, and the standard of the flowering shoots was good. Seven gentle spectra had been examined, which differed primarily within the proportion of blue and far-red gentle.

Stem elongation
Probably the most putting consequence was the stem elongation within the therapy by which the day was prolonged for half-hour with 20 µmol/m2/s far crimson gentle (EOD, finish of day therapy). Stem elongation was already noticed after two weeks, and resulted in longer flowering shoots within the three truss varieties. This was even though vegetation on this therapy had been sprayed twice with development retardant, in distinction to the opposite therapies, which had been sprayed solely as soon as. When far-red gentle was used to complement gentle all through the day, there was hardly any impact on stem size. Moreover, the sunshine spectrum additionally affected growth charge of the flowers. On common, flowers of the EOD FR therapy had been harvested two days sooner than the reference RGB (5% blue, 5% inexperienced and 90% crimson gentle). Stem weight was not affected.

Observe-up analysis
This analysis exhibits that stem elongation in chrysanthemum will be managed by gentle spectrum. Utilizing a low-intensity far-red gentle for half an hour on the finish of the day ends in longer flowering shoots with out (a lot) extra vitality. These outcomes nonetheless go away us with some questions on the usage of finish of day far-red gentle: ought to it’s given for half an hour, or can it’s much less? Wouldn’t it be ample to present the EOD far-red gentle solely within the first 2-3 weeks of cultivation? What depth of far-red gentle is required? These questions ought to be answered in subsequent trials.

For extra info:
Wageningen College & Analysis