SYNERGISTIC ACCELERATION OF BEGONIA SEMPERFLORENS DEVELOPMENT USING SUPPLEMENTAL IRRADIANCE AND SOIL HEATING.

Begonia semperflorens ‘Vodka’ was sown either 10 Dec. or 15 Feb into 512 plug flats.
Upon seedling emergence, plants were given supplemental 24 h HPS irradiance treatments at either 13, 73, 118 or 233 μmol m^-2s^-1 for 5 or 10 day periods.
Seedlings were grown at ambient or 27C root zone temperatures.

Root zone heating increased seedling dry weight 15% at 13 μmol m^-2s^-1 compared to ambient temperatures.
Increasing irradiance from 13 to 233 μmol m^-2s^-1 increased seedling dry weight 25 and 33% when seedlings were grown at ambient and 27C respectively.
The influence of supplemental heating on growth rate varied depending upon stage of development and treatment duration.
A ten day supplemental heating treatment which included days 10 to 15 after germination (ie. 5 to 15 or 10 to 20) resulted in a 20% increase in dry weight.
Treatment for 5 days during this period was not as effective as the ten day treatment duration.

Symposium on Bedding and Pot Plant Culture

David F. Graper, W. Healy

https://doi.org/10.17660/ActaHortic.1990.272.37