Combined Effects of Light and Temperature on Product Quality of Kalanchoe Blossfeldiana

Abstract

) combined with four constant temperatures (18, 21, 23 and 26°C; equal day and night temperature) was conducted in growth chambers using the pot plant Kalanchoe blossfeldiana. The current work allows for establishing relationships between these two climatic factors and product quality (plant height, number of flowering shoots, inflorescence size and inflorescence position) and cropping duration. From the studied product quality attributes, temperature and PPFD only showed a marked interaction on number of flowering shoots and on inflorescence size. The huge increase observed on the number of flowering shoots (from 4.6 to 20.5) was a response to higher PPFD, whereas temperature had only a minor effect. Inflorescence size was also enhanced at higher PPFD (especially at lower temperatures) but in contrast with the number of flowering shoots, inflorescence size was drastically reduced at higher temperatures. Plant height varied between 13.5 and 21.6 cm and was strongly influenced by temperature, whereas influence of PPFD was only marginal. Time to flowering decreased quadratically with temperature and with PPFD, and no interaction between these climatic factors was found INTRODUCTIONSupplementary lighting is increasingly used in greenhouse horticulture in areas where in part of the year natural light level is not sufficient for acceptable yield and product quality (Marcelis et al., 2002). Particularly in greenhouse ornamental production, supplementary light is a prerequisite to allow a year-round production (e.g. photoperiodic treatments for flowering control) and to reduce the variation in product quality throughout the year (e.g. increasing the autumn and winter quality). For optimal use of supplementary lighting a good understanding of the effects of light and possible interactions with other climatic factors on crop growth, development, yield and product quality is necessary.Explanatory simulation models are known to be powerful tools to analyse quantitatively the effects of supplementary lighting on crop growth (Marcelis et al., 2002) and this analysis can be further extended to several external quality attributes (e.g. Carvalho and Heuvelink, 2004). Kalanchoe growers aim at producing a compact plant, with richly flowering umbels and one to three open flowers at commercial harvest, in the shortest time as possible. In a previous study a conceptual dynamic model for predicting plant height and number of flower heads in Kalanchoe blossfeldiana was developed (Eveleens-Clark et al., 2004). In order to use this conceptual model as a decision support system for year-round kalanchoe production, it needs to be further extended, parameterised and calibrated for different seasons. Therefore, information is needed on the effects of photosynthetic photon flux density (PPFD) and temperature on product quality and cropping duration.

EFFECT OF COLD NIGHT TEMPERATURE ON FLOWERING OF Kalanchoë SPECIES

“…In E1, plants were established during summer and had higher influence of external light in the greenhouse, while E2 established in autumn with less natural light, and thus exhibited lower quality of flowering. These observations from both experiments are consistent with the findings of Carvalho et al [2006] who demonstrated that the height and number of flowers for K. blossfeldiana increased when the plants received more irradiation. These authors also showed that plants exposed to higher irradiance flowered earlier.…”

Quantification of the Growth Response to Light Quantity of Greenhouse Grown Crops

“…A decrease of 0.8-1% dry weight at 1% light reduction was found for Kalanchoe (e.g. Gislerød et al, 1989;Mortensen, 1994;Carvalho et al, 2005). In flowering pot plants other factors like plant morphology, leaf colour and shelf life are more important for the grower than weight, and light also has clear effects on these quality aspects.…”

“…Some examples are that the number of flowers decrease at low radiation (e.g. Carvalho et al, 2005), while leaves may become pale at high light levels (e.g. Andersson, 1994).…”

Temperature Impacts Cactus and Succulent Development Rate

“…• February 2017 27(1) desert climates (Table 1). Kalanchoe reportedly has an optimal temperature at or near 24-26°C (Carvalho et al, 2006); 'Silver Dollar' jade here (similar indigenous location as kalanchoe) had a similar optimal temperature (Table 2). In contrast, species with optimal development rate temperatures ‡28°C here ('Firebird' aloe, tiger tooth aloe, zebra plant, prostrate rainbow bush, and 'Arizona Snowcap' mammillaria) are indigenous to interior regions, lowlands, or deserts of South Africa, or central Mexico with warmer temperatures (Table 1).…”

“…Intermediate temperature (similar to here) effects on development rate of some succulents and tropical cacti have been studied. Kalanchoe [Kalanchoe blossfeldiana (indigenous to Madagascar; Bailey, 1976)] time to flower decreased 19 d when temperature increased from 18 to 24°C, but decreased only 2 d more when temperature was increased further from 24 to 26°C (Carvalho et al, 2006). Thanksgiving cactus [Schlumbergera truncata (indigenous to Brazil; Bailey 1976)] days from flower induction to anthesis decreased from 100 to 52 d when average daily temperature increased from 12 to 20°C and was unchanged when average daily temperature was further increased from 20 to 24°C (Erwin et al, 1990).…”