Reproductive traits such as fruit set, pollen traits are crucial for the development of novel hybrids in ornamental plants including dendrobiums. Orchids contain ‘pollinia’ as their pollen dispersal units, where a large number of pollen grains are packed together. Pollination of orchids occurs by the deposition of pollinia in the receptive stigmatic cup. Pollen viability and pollen germinability are considered as indicators of a successful hybridisation process.
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Indigenous Dendrobium species (A) D. crumenatum and (B) D. anosmum and commercial Dendrobium hybrids (C) Dendrobium ‘Big Jumbo’, (D) Dendrobium ‘Emma White’, (E) Dendrobium ‘Pink’, (F) Dendrobium ‘Lemon Yellow’ , (G) Dendrobium ‘Arading Green’, (H) Dendrobium ‘Nana Red’, (I) Dendrobium ‘Mickey Pinky Splash’, (J) Dendrobium ‘Visa Peach’, (K) Dendrobium ‘Sonia red’ and (L) Dendrobium ‘Happy Star’. |
In the present research, pollen viability, germinability and success in seed production of two indigenous Dendrobium species and ten commercial hybrids of Dendrobium were compared to determine the fitness traits and the possibility of the compromising of fitness in commercial hybrids. Reproductive ecology of indigenous and commercial hybrids were studied by observing visits of natural pollinators. Floral characters that are associated with different groups of pollinators were assessed to determine the type of pollinators that are associated with the studied dendrobiums. Effect of pollen storage temperature on seasonally flowering D. crumenatum pollen viability was assessed to determine the suitable pollen storage method for the benefit of breeding programmes.
Indigenous species, D. crumenatum and D. anosmum, showed the highest pollen viability and germinability while only 40% of the commercial hybrids had viable pollen and could be identified as desired hybrids for successful breeding programs. D. crumenatum pollen can be stored at 9°C maintaining its viability for 14 days for successful cross-pollination. Although all tested dendrobiums predicted to be pollinated by bees, they failed to set fruit under natural pollination due to the lack of native pollinators in the suburban environment. Thus, fruit set in tested dendrobiums were reported only through hand pollination. In addition, indigenous D. crumenatum can be recommended to use as pollen donors in cross-pollination programmes. Our findings facilitate the selection of parents with desired traits of promising features to create novel hybrids for commercial purpose.
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