| Summary: | 碩士 === 國立屏東科技大學 === 熱帶農業暨國際合作系 === 106 === Orchid micropropagation is the process used to replicate and mass rapid clonal propagation of plant in vitro by which a technique that commonly referred as tissue culture. Media for plant tissue culture should generally contain some or all of the macronutrients, micronutrients, vitamins, amino acids or nitrogen supplements which are the source of carbon, undefined organic supplements, growth regulators and solidifying agents. Plant biostimulator is a substance or microorganism that is applied to plants which can enhance nutrition efficiency, abiotic stress tolerance and crop quality traits, depending on its nutrients and hormone content. Therefore this study aimed to investigate the growth and physiological effect of orchids by using two natural biostimulator supplements. Seedlings of five different orchid species (Rhynchostyli coelestis, Dendrobium linguiforme, Brassolaeliocattleya Guan Miao City, Laeliocattleya Dianrd x Brassolaeliocattleya Guan Miao City and Angrecum leonis) were planted on 1/2 Murashige and Skoog contain 30 g / L sucrose, 8 g / L agar and supplemented with 0 (control), 5, 10 and 20 mg / l of different biostimulators [chitosan (c) and sericin (s)] each flasks. The pH of the media is adjusted to 5.7 ± 0.05 the seedlings were cultured in the controlled condition at 25 ± 1 °C, 12/12 day/night photoperiod under cool-white fluorescent tubes. After 215 days of culture, the results showed that the supplementation of biostimulator included in the media can increase the growth of orchid seedlings. Moreover, the growth of orchid seedlings (root, shoot and height) are highly significant compared to control. The growth of Rhynchostylis coelestis in the medium supplemented with sericin 20 mg / l was higher than other treatments. However, fresh weight and dry weight showed no difference. In addition, this study also showed that biochemical properties such as nitrogen including sugar and starch accumulation were not significantly affected by the supplementation of biostimulators. Dendrobium linguiforme growed slowly and remained small in all treatments except the treatment with chitosan 20 mg / l which exhibited higher fresh and dry weight including sugar and starch accumulation. Brassolaeliocattleya Guan Miao City orchid seedlings grew slowly and were not different excluding the fresh weight of the treatment with sericin 20 mg / l which had a higher significant difference. The hybrid orchid grew in (Laeliocattleya Dianrd x Brassolaeliocattleya Guan Miao City) supplemented with chitosan and sericin were nearly the same but chitosan 10 mg / l were higher in terms of number of leaves, leaf length and height. Lastly, Angrecum leonis orchid grown after 215 days showed a significant difference and it was clearly that better growth on number of root, root length and plant height (sericin 20 mg / l). Chitosan and sericin all had chemical properties as a biopolymer which contains many amino group (-NH2) and isolation as the ammonium fertilizer for plants. On the other hand, the growth of orchid could be decreased when an increased concentration of both biostimulators are used. This may be due to ammonium toxicity at high concentrations. The starch and nitrogen analysis in orchid indicated and confirmed that chitosan and sericin supplemented in culture medium could stimulate the growth of orchid as well. In conclusion, the result with the positive responses and growth in this study indicated that it is possible to these biostimulators in Murashige and Skoog medium and supplement and promote in vitro orchid seedling growth. The combination with chitosan 20 mg / l suitable for Dendrobium linguiforme supplemented with sericin 20 mg / l for Rhynchostylis coelestis, and Angrecum leonis. A suitable concentration for the hybrid orchid (Laeliocattleya Dianrd x Brassolaeliocattleya Guan Miao City) was chitosan 10 mg / l.
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