Long-term Exposure of Mother Plants to Low Temperatures Delays Flowering of Japanese Autumn-flowering Chrysanthemum morifolium Ramat. ‘Jinba’ and ‘Seiko no Aki’

Abstract

To clarify the reason for delayed flowering of Chrysanthemum morifolium 'Jinba' cuttings propagated from mother plants during winter and spring production, the effects of growing temperatures of mother plants, and those of rooted cuttings grown in long days or short days, on vegetative growth and flowering in three autumnflowering Chrysanthemum cultivars were investigated. Rooted cuttings of 'Jinba', propagated from mother plants exposed to two temperature regimes, were planted on December 26 and grown in two temperature regimes with long days. Plants with each treatment were then grown with short days using two temperature regimes. Flowering of rooted cuttings propagated from mother plants exposed to ambient low temperatures and grown at 25/10°C (7:00-19:00/19:00-7:00) with long days, and subsequently grown at 25/20°C or 25/10°C with short days, was delayed 11.4 and 14.4 days, respectively, compared with cuttings propagated from mother plants grown at a minimum temperature of 15°C. In a further experiment, the mother plants of three autumn-flowering cultivars were grown at four temperature regimes of 7°C, 10°C, 13°C, or 16°C for 50 days. Flower budding of 'Jinba' and 'Seiko no Aki' was delayed and the increase in leaf number (ILN) with short days was greater when mother plants were grown at 7°C or 10°C compared with plants grown at 16°C. In contrast, flower budding of 'Shuho no Chikara' cuttings propagated from mother plants grown at 7°C or 10°C was accelerated and the ILN decreased compared with those grown at 16°C. Clearly, delayed flowering of 'Jinba' and 'Seiko no Aki' was due to longterm exposure of mother plants to temperatures below 10°C. For suitable flowering of these cultivars, mother plants should be grown at a temperature exceeding about 15°C or the plants must be grown at a high temperature with long days for several weeks.

Exposure of Rooted Cuttings to Long Days, or Mother Plants to High Temperature, Can Avoid Delayed Flowering of Chrysanthemum morifolium Ramat. ‘Jinba’ for Winter and Spring Cut-flower Production

“…However, in the autumn-flowering chrysanthemum 'Jinba', stem elongation and leafing are rapid in long days, but flower budding and flowering are markedly delayed during winter and spring cut-flower production. Tanigawa et al (2001) and Kunitake et al (2009) reported that to avoid delayed flowering of 'Jinba', the plants must grow at high temperature not in short days (i.e., in the reproductive growth stage) but in long days (i.e. in the vegetative growth stage) for several weeks, or alternatively the mother plants should be grown at high temperature.…”

“…Kunitake et al (2009) have reported in regard to entering 'juvenile phase'; however, there are few reports that about the temperature or period of how long exposure to high temperature is required to pass through the 'juvenile phase'. To avoid delayed flowering of plants, mother plants can be grown in a heated greenhouse to avoid the rosette or juvenile stage.…”

“…Stem elongation and leafing of plants are rapid in long days (the vegetative growth stage) at a comparatively low night temperature of 10-13°C and with low radiation in autumn and winter, whereas flower budding and flowering are delayed remarkably in short days, even in a heated greenhouse at a minimum temperature of 20°C during winter and spring cut-flower production. Tanigawa et al (2001) and Kunitake et al (2009) reported that the factor responsible for delayed flowering of 'Jinba' or 'Seiko no Aki' was the exposure of mother plants to a temperature below 10°C for an extended period. It was also confirmed that rooted cuttings of 'Jinba' propagated from mother plants exposed to low temperature acquired another vegetative growth stage in which flower buds could not be induced after passing through the rosette stage .…”

Análise das vias genéticas reguladas pelo microRNA156 e o gene <i>SINGLE FLOWER TRUSS (SFT)</i> em resposta a baixa temperatura no controle do florescimento de tomateiro (<i>Solanum lycopersicum L.</i>)

“…A temperatura ambiental pode afetar o período de transição da fase adulta vegetativa para adulta reprodutiva em muitas espécies (BERNIER; PÉRILLEUX, 2005). Por exemplo, curta exposição à temperatura ambiental promove o florescimento em Phalaenopsis (WANG et al, 1995) e Pharbitis (TAKENO et al, 2016), inibindo emChrysanthemum(KUNITAKE et al, 2009) e Arabidopsis thaliana(KIM et al, 2012). Embora o tomateiro floresça de forma autônoma, estudos sugerem que fatores ambientais estejam envolvidos na modificação do padrão de florescimento(SAMACH;LOTAN, 2007).…”