Refinement of nutrient management practices in dendrobium orchids

Abstract

Twenty five fragrant vandaceous orchids were evaluated in the Department of Floriculture and Landscaping during the period from June 2016 to May 2017 with the objective of classifying them based on aesthetic and economic parameters for commercial exploitation as value added plants. The varieties exhibited wide variation in both vegetative and floral characters. Considering quantitative characters, Vasco Crownfox Red Gem recorded the maximum plant height (68.73cm), spread (52.23cm), internodal length (1.95cm) and leaf length (33.83cm). V. Pranerm Prai x V. tessellata showed maximum shoot girth (4.99cm), leaf area (105.54cm2), leaf number (37) and root length (181.75cm). The least values for all these characters were for Neostylis Lou Sneary. Duration from spike emergence to opening of florets was the maximum in Ascda Peggy Foo x Rhyn. Coelestis Blue and minimum in Neostylis Lou Sneary. Maximum spike longevity was recorded in V. Rothschildiana (29.30 days) whereas it was minimum in Rhy Sri Siam x Rhy gigantia (7.50 days). Interval of spike production was also the longest in Ascda. Peggy Foo x Rhyn. coelestis Blue and the minimum in Rhynchorides Bangkok Sunset. Spike production was the maximum in Neostylis Lou Sneary, followed by Ascda Srichai and Vasco Crownfox Red Gem. The varieties/ hybrids varied with regard to blooming period. The peak flowering was from May to July. Longer spike and rachis were noticed in Aerides quinque Vulnera Rhy. Coelestis. Vasco Blue Bay Pink had the highest number of florets/ spike and the shortest internodal length. Largest flowers were observed in V. Rothschildiana. Petal and labellum of the varieties also exhibited different colour patterns such as uniform, spotted, netted, tessellated and shaded. All the evaluated varieties were fragrant and were categorized based on different notes such as floral, fruity, spicy, green, sweet and miscellaneous. Fragrance was very faint in V. Rothschildiana whereas it was musty in Darwineria Cream Puff. With respect to the post-harvest characters longevity (vase life) was the maximum in V. JVB X Ascda Yip Sum Wah (17.30 days) and individual floret life (8.13 days) in V. Rothschildiana. Colour and pigmentation, texture, shape, pattern and size of florets as well as arrangement of florets on the spike were considered for the visual evaluation of a variety for use as cut flower. Considering the overall qualitative and quantitative attributes, Vascostylis Crownfox Red Gem, Vasco Blue Bay Blue, Rhynchorides Bangkok Sunset, V. Mimi Palmer, V. JVB X Ascda Yip Sum Wah and Vasco Blue Bay Pink were excellent for cut flower production. Plant quality evaluation was done based on fullness, growth and visual appearance, flower colour and pigmentation, spike longevity, shape and arrangement of foliage during the growth period. Fragrance scoring was also done based on intensity and diffusiveness, newness and beautifulness of fragrance. Based on the flowering phenology, four phenophases, namely, November – January, February – April, May – July and August – September were recorded and the varieties were categorized accordingly. Side-runs with different colour combinations were observed within a phenophase. The varieties were also categorized on the basis of flower colour, number of florets/ spike and floret size, longevity of spike on the plant , number of spikes produced / year and fragrance. Considering overall quantitative and qualitative characteristics, the evaluated varieties/ hybrids were categorized for cut flower, indoor and outdoor gardens for commercial exploitation as value added plants. The fragrance also makes it a novelty in landscaping to create a peaceful, relaxing environment.