PhD Thesis

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    Performance of selected orchids under varying light regimes, culture methods and nutrition
    (Department of Horticulture, College of Agriculture, Vellayani, 1996) Sabina George Thekkayam; Mohanakumaran, N
    The present study was undertaken to evolve agrotechniques for cut flower orchid production in Kerala. Two experiments were conducted at the College of Agriculture, Vellayani in 1991 and 1992 with two popular cut flower varieties namely Arachnis Maggie Oei ‘Red Ribbon’ and Dendrobium Sonia – 16. The effects of varying light intensities and nutrient regimes under two methods of cultivation were assessed in Arachnis Maggie Oei ‘Red Ribbon’ (Experiment 1) and in Dendrobium Sonia -16, the performance under varying light intensities and nutrient regimes was evaluated (Experiment 2) In Arachnis Maggie Oei ‘Red Ribbon’, trench culture was found to promote growth, flowering and the floral attributes. The number of leaves, aerial roots, leaf area and plant height were greater in the trench grown plants. The number of inflorescences produced, their branching, length and vase life were also enhanced under trench culture. The effect of light intensities on growth was mediated through interactions with culture methods and nutrients. The trench grown plants under 50 and 75 percent light had a greater number of leaves and leaf area. The plants receiving 500 ppm of P and K under 100 percent light had a shorter stature. The direct effect and interactions of nutrients on growth were observed at certain months during the experimental period which was indicative of differences in the requirement at different stages of growth. The dry matter content of the stem and apical shoot was greater in the plants receiving 500 ppm P. Inflorescence production and the vase life of inflorescences was greater under 100 and 75 percent light. Branching of inflorescences was greater under 75 percent light. In Dendrobium Sonia -16 the number of inflorescences produced was greatest under 75 percent light. The length of the inflorescences was greater under 75 percent light and the span area of the flowers was greater under 50 and 75 percent light. Nitrogen at 500 ppm increased the length of the inflorescences, the number of flowers in an inflorescence, and the span area of the flowers. The number of inflorescences produced was also greater in the plants receiving 400 or 500 ppm N, 400 or 500 ppm K and in those receiving 500 ppm P. Interactions between the nutrients and between light intensities and the nutrients were also observed. The nutrient composition of the leaves in both the cultivars were enhanced by the 400 and 500 ppm doses of N and P and 500ppm K. Based on the observed effects, in Arachnis Maggie Oei ‘Red Ribbon’, trench culture of plants under 75 to 100 percent light and a nutrient dosage of 300 ppm N, 400 ppm P and 300 ppm K from planting till nine MAP and thereafter a dosage of 400 to 500 ppm N, 400ppm, P and 500 ppm K can be recommended. In Dendrobium Sonia -16 growing in pots under 75 percent light with 400 to 500 ppm of N, P and K can be recommended
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    Intra and inter generic hybridization and molecular charatrization in monopodial orchids
    (Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2008) Beena Thomas; Lekha Rani, C
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    Distant hybridization and compatibility studies in wild orchids
    (Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2018) Seeja, G; Arya, K
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    Seed germination and tissue culture studies in orchids
    (Division of Horticulture, University of Agricultural Sciences, Bangalore, 1982) Ramachandran Nair, S; Foja Singh
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    Regulation of flowering in phalaenopsis orchids
    (Department of Pomology and Floriculture, College of Horticulture, Vellanikkara, 2012) Kaveriamma, M M; Rajeevan, K
    Studies on ‘Regulation of flowering in Phalaenopsis orchid’ were conducted in the Department of Pomology and Floriculture, College of Horticulture, Vellanikkara from November 2010 to April 2012. The main objectives were to evaluate cut flower and pot plant varieties of Phalaenopsis hybrids under two microclimatic conditions, to observe their flowering behaviour with respect to the weather elements and to study the effect of cultural practices on flowering and floral characters Orchidaceae is the largest family in the plant kingdom with over 25,000 species in over 600 genera. Despite the diversity, very few genera like Cymbidium, Phalaenopsis, Dendrobium, Oncidium and Cattleya are ranked high commercially. The genus has around 80 species and more than 40,000 hybrids. It is a short stemmed epiphytic monopodial orchid with Crassulacean Acid Metabolism (CAM) pathway of photosynthesis. Based on floral characters, phalaenopsis are broadly classified as grandiflora (cut flower) and multiflora (pot plant) types. Grandiflora types have long, arching inflorescence with large flowers, whereas, the multiflora types have short, branched inflorescence with numerous smaller sized flowers. Phalaenopsis is now among the most valuable flowers used as cut flower and as pot plant. As a part of the study, phalaenopsis varieties were evaluated under two different growing systems, viz., top ventilated rain-shelter and fan and pad system of greenhouse. Vegetative growth was better in rain-shelter whereas longer flowering period and higher flower count were obtained under fan and pad system. In an attempt to induce flowering by exposing to lower temperature, plants were taken to Nellaimpathy, having an altitude of 1050 meters, and were kept for different periods. Keeping for three weeks was the best in terms of inflorescence induction as compared to control. Subsequently, comparable situation was provided in an AC room. Plants kept for two weeks initiated inflorescence. Nutrient and growth regulator treatments had no significant impact on growth and flowering. Pruning of spent inflorescence induced new inflorescence and the best treatment was pruning above the first node. Commonly used media for growing phalaenopsis are coconut husk chips and coconut husk bits, along with charcoal and tile bits. Use of sphagnum moss has been reported from other countries only as media for good moisture retention. In the present study, plants grown in sphagnum moss were significantly superior to coconut husk chips and coconut husk bits as media, both in terms of vegetative and floral attributes. It was high in chlorophyll content along with high N, Mg, S, Fe and Mn, which are responsible for photosynthesis. N fixing bacteria Klebsiella pneumonia and Bacillus thuringensis were also found in plants grown using sphagnum moss. Post harvest studies conducted to evaluate the longevity of floret and spike in plain water indicated differences among varieties. Var. Mimi had maximum inflorescence longevity and variety Roxenne the minimum. Physiological studies showed stomatal conductance, net CO2 assimilation reaching peak at 4am. Stomatal density was higher on the abaxial leaf surface in all varieties. Titable acidity as malic acid accumulation was higher in rain-shelter compared to fan and pad, indicating better growth.