A new Dendrobium cultivar: Den. ‘Aurora’s Orange Hana’

Abstract Dendrobium is a large genus of orchids containing more than 1800 species spliced in some sections and many are very attractive such as the group Nobile from section Dendrobium. They are an easy-to-cultivate ornamental group with pseudobulbs cane-like, mostly hard, erect, covered by the bases of the leaves and flowering in almost all internodes. In this work, we tried to develop a cultivar of small size with floriferous plants. The hybrid Dendrobium Aurora’s Orange Hana was produced and showed compact and floriferous plants with varied colours among the offspring. Three superior clones were selected due to a better display, architecture, three to four flowers per node, and vibrant colours. This new cultivar can be easily grown in pots or on living supports, forming compact and very flowering clumps.

Since 1957, Jiro Yamamoto has started improving the quality of Dendrobium nobile through hybridisation.He noted that tetraploids were healthy, easy to grow, and resistant to insects and disease, and most of them produced larger flowers.He worked with polyploid parents, and in more than 50 years, he created about four thousand types of Dendrobium nobile, the Royal Horticultural Society (RHS) named his hybrids of ' Yamamoto type' (Teoh, 2021).Among the Yamamoto hybrids the Den.Oriental Smile 'Fantasy' has orange flowers with a light lilac brush on the tips of the petals and Den.Spring Dream 'Apollon' has pure white flowers, a greenish-yellow eye, and a relatively small plant size, a great characteristic for commercialisation and hybrids from this famous collection (Yamamoto, 2010).
Breeding new varieties of ornamentals has many variations, but nowadays, such varieties must be well balanced between crop production, environmental sustainability and conservation (Bugallo and Facciuto, 2023;Datta, 2022, Zuo et al., 2023).Although Dendrobium breeding it is not new, neither in the world (Yi et al., 2022;Zheng, et al., 2018;Rao et al., 2021) nor in Brazil (Cardoso et al., 2020, Cardoso, 2012;Faria et al., 2011;Faria et al., 2009), but in Brazil is relatively recent.This program aims to obtain new cultivars with agronomic importance, such as resistance to pests and diseases, rapid growth and quality and durability of flowers, economic viability to be competitive with other species of orchids of ornamental importance such as Phalaenopsis and Dendrobium imported cultivars and hybrids (Cardoso, 2012).

Origin
Dendrobium Aurora's Orange Hana was an offspring of the cross between Den.Oriental Smile 'Fantasy' X Den.Spring Dream 'Apollon'.The register occurred in the Royal Horticultural Society, under the number 27126, in May 2017.The capsule developed for six months and was collected when it showed the first signs of maturation.It was kept in an envelope of thin paper and allowed to ripe naturally in a chamber over a layer of silica gel (Seaton et al., 2018).
Seeds were disinfested for 10 minutes using a 5 g L -1 of sodium dichloroisocyanurate solution added with 100 µL of Tween 80 as a wetting agent and mixed by inverting the tubes by hand during this period (Oliveira et al., 2022).Afterwards, seeds were washed twice in distilled autoclaved water and sown in a ½ strength MS media with 20 g L -1 of sucrose and 8 g L -1 of agar; the pH of the media was adjusted to 5.6 before sowing The media was autoclaved and distributed in Petri dishes (80 mm of diameter) and Petri dishes were sealed with PVC film and transferred to a growth room at 25 ± 3 ºC on a 16 h light / 8 h dark cycle and light provided at 511 μE m −2 s −1 (Fileti et al., 2021).After 60 days, seedlings were transferred into flasks and allowed to grow for 90 days when the plants were replanted into another flask, repeating this procedure until the seedlings were ≥ 20 mm high.Seedlings were removed from the flasks, carefully washed off the agar debris, and immersed in a solution containing 2 g L -1 of methyl tiophanate for one hour.The solution was drained, and the seedlings allow to dry overnight.
The seedlings were planted in community pots using sphagnum moss as substrates and received weekly fertilisation using a hydrosoluble feed, a 20:20:20 formula at 1 g L -1 .If pests or diseases were found, the plants were sprayed with a proper insecticide or fungicide, normally imidacloprid and methyl tiophanate, respectively.After one year, the plants were transferred to individual pots (5 cm) filled with 1/3 of gravel and a pine bark potting mix of fine granulometry (<5mm) and chopped Sphagnum moss (1:1, v v -1 ).When the plants were 10 cm height, they were transferred to 7.5 cm pots with 1/3 gravel and a medium granulometry (< 12 mm) until flowering, which happened two years after deflasking.

Morphological Description
Two years after deflasking, the offspring exhibited their first bloom and was named Dendrobium Aurora's Orange Hana (Figure 1).However, many criteria are relevant for selection, e.g., earliness and colour (Machado-Neto et al., 2022;Colombo et al., 2017;Machado-Neto, 2019).Three plants were selected because of their compactness, with an average of 15cm and denominated #1, #2 and #3.The number of flowers per spike ranges from three to four per node, and they remained in good condition for 21 days.

Adaptability (climate, regional and pest tolerances)
Den. Aurora's Hana have been cultivated in the west São Paulo Region, with a hot (26.6 ºC mean temperature, with peaks of 32 ºC) and rainy summer and a dry winter (~21 ºC mean temperature, with very uncommon frosts), and 1314mm of annual rainfall (Figure 2, Climate data, 2023).

Selection of Superior Clones, Conservation and Multiplication
The superior clones Den.Aurora's Orange Hana were selected based upon the criteria described above, were separated and included as parents in our breeding program and are described in Table 1.

Material Characteristics
Den. Aurora's Orange Hana is a small-sized plant (maximum 25 cm high).The flowers are up to four in each bunch.The flowers are small-medium sized, from white with hints of pink to yellow and a dark mid-purple blotch in the labellum.

Growing Conditions
The plants are currently maintained in black plastic pots filled with broken macadamia nut shells in a shade house (50% of shadow), fertigated once a week with a 15-05-15 NPK (0.24 g m -2 ) plus secondary macro and micronutrients (PETERS Excell Mag ® ).The commonly used phytosanitary practices for orchid cultivation were applied.

Performance (productivity data and comparison with commercial cultivars)
The plants are shorter in size but keep the floriferousness compared with both parents.Den.Aurora's Orange Hana grows well either as pot plants or in living supports, developing nice clumps full of flowers in the winter/springtime.

Originality
This article is original, prepared and submitted just to this Journal.

Table 1 .
Selected clones of Dendrobium Aurora's Orange Hana and their floral characteristics.