TY - JOUR

T1 - Effect of photoperiod and temperature on flower induction in three Aizoaceae genera

AU - Braun, P.

AU - Winkelmann, T.

PY - 2016

Y1 - 2016

N2 - Midday flowers (Aizoaceae), whose origin and main area of distribution are located in southern Africa, represent the most species-rich family of succulent plants. Because of their intensively colored flowers, a high diversity of growth forms and relatively high tolerance to drought, several Aizoaceae species are attractive candidates for breeding approaches or direct use as ornamental plants. Despite their advantageous characteristics, midday flowers are rarely offered for sale in Central Europe and only a few commercially traded cultivars were developed so far. A wider use of midday flowers as ornamental plants requires intimate knowledge of means to control their cultivation (e.g., control of flowering time), which is underreported up to now. The present study aimed at determining the effects of different photoperiods and temperatures on flower induction in the genera Delosperma, Cephalophyllum and Lampranthus in two separate experiments conducted in controlled environments. Day length could be ruled out as a flower-inducing factor, because flower organs were observed irrespective of photoperiods (16 h, 9 h and 9 h + 2 h night interruption) in genotypes of all three genera. However, only plants cultivated under longday conditions (16 hours of daily exposure to light) had a desirable appearance, which was reflected in significantly higher dry matter contents. Cultivation in climate chambers for several weeks revealed distinct impacts of mean daily temperatures (MDT) on flower formation. The investigated Delosperma genotype tended to develop more flowers at 20°C than in two variants in which the plants were exposed to 14°C MDT. In contrast, cultivation at 14°C MDT resulted in significantly higher flower numbers in two Lampranthus genotypes. High numbers of flowers were found in the investigated Cephalophyllum genotype at both MDTs and significant differences were not detected.

AB - Midday flowers (Aizoaceae), whose origin and main area of distribution are located in southern Africa, represent the most species-rich family of succulent plants. Because of their intensively colored flowers, a high diversity of growth forms and relatively high tolerance to drought, several Aizoaceae species are attractive candidates for breeding approaches or direct use as ornamental plants. Despite their advantageous characteristics, midday flowers are rarely offered for sale in Central Europe and only a few commercially traded cultivars were developed so far. A wider use of midday flowers as ornamental plants requires intimate knowledge of means to control their cultivation (e.g., control of flowering time), which is underreported up to now. The present study aimed at determining the effects of different photoperiods and temperatures on flower induction in the genera Delosperma, Cephalophyllum and Lampranthus in two separate experiments conducted in controlled environments. Day length could be ruled out as a flower-inducing factor, because flower organs were observed irrespective of photoperiods (16 h, 9 h and 9 h + 2 h night interruption) in genotypes of all three genera. However, only plants cultivated under longday conditions (16 hours of daily exposure to light) had a desirable appearance, which was reflected in significantly higher dry matter contents. Cultivation in climate chambers for several weeks revealed distinct impacts of mean daily temperatures (MDT) on flower formation. The investigated Delosperma genotype tended to develop more flowers at 20°C than in two variants in which the plants were exposed to 14°C MDT. In contrast, cultivation at 14°C MDT resulted in significantly higher flower numbers in two Lampranthus genotypes. High numbers of flowers were found in the investigated Cephalophyllum genotype at both MDTs and significant differences were not detected.

KW - Cephalophyllum

KW - Delosperma

KW - Lampranthus

KW - Midday flowers

KW - Novel ornamentals

KW - Succulent plants

UR - http://www.scopus.com/inward/record.url?scp=84988418424&partnerID=8YFLogxK

U2 - 10.17660/ejhs.2016/81.4.3

DO - 10.17660/ejhs.2016/81.4.3

M3 - Article

VL - 81

SP - 204

EP - 211

JO - European Journal of Horticultural Science

JF - European Journal of Horticultural Science

SN - 1611-4426

IS - 4

ER -