104 Karnataka J. Agric. Sci.,25 (1) : (104-107) 2012 Evaluation of Dendrobium orchids for growth and yield grown under greenhouse* S. SUGAPRIYA, J. C. MATHAD, A. A. PATIL, R. V. HEGDE, S. LINGARAJU AND M. S. BIRADAR Department of Horticulture, University of Agricultural Sciences,Dharwad-580 005, India Email: sugisundaram@yahoo.co.in (Received : July, 2009 ; Accepted: December, 2011) Abstract: Dendrobium is one of the important genera of orchid and grown commercially for cut flowers. Therefore evaluation of its growth habit, flowering behaviour and yield under the different growing conditions for a location specific is important. Nine varieties of Dendrobium orchids were evaluated for growth and yield. The study revealed that among the different varieties evaluated, Sonia-17 recorded maximum plant height (54.57 cm), length of internode (5.00 cm) and number of pseudobulbs per plant (9.73), where as Medame uraiwan registered more number of leaves (18.33) and maximum pseudobulb girth (6.23 cm). Maximum leaf length (16.5 cm) was recorded in Burana fancy where as leaf breadth was maximum (4.9 cm) in the varieties Sonia-17 and Medame uraiwan. Physiological growth parameters viz. leaf area (61.06 cm 2 ), leaf area index (7.3) and leaf chlorophyll content (80.53 SPAD units) were registered maximum in Sonia-17. The varieties Sonia-17 (187.13 days) and Somark white (201.67 days) have taken less number of days for flower bud initiation where as Sonia-17 exhibited minimum time interval from flower bud initiation to first flower opening and first flower opening to harvest (31.43 days and 27.67 days respectively). Out of the nine varieties studied, Sonia-17 exhibited free-flowering nature and seasonal flowering was observed in rest of the varieties. The number of spikes per plant per year (8.67) was recorded maximum in the variety Sonia-17. Key words : Orchids, Dendrobium, Varieties, Growth, Yield Introduction Orchids, more than any other plants, exert a mysterious fascination for most people and all the wild orchids of tropical regions are highly puzzling and peculiar. Orchids exhibit an incredible range of diversity in size, shape and colour of their flowers. They culminate one of the evolutionary lines of monocots and are still in an active state of speciation (Vij, 1995). Orchids have a very wide range of distribution. They are found to occur in all parts of the world except, perhaps, in the Antarctica. Though the family is cosmopolitan, many more species are found in the tropics than in the temperate regions (Abraham and Vatsala, 1981). The genera of orchids which are commercially important are Cymbidium, Dendrobium, Phalaenopsis, Oncidium, Vanda, Mokara, Arachnis and Cattleya (Hew, 1994 and Laws, 1995). Among these genera, Dendrobiums are most popular tropical orchid getting fame as cut flowers in India as well as in the world. The orchids especially Dendrobiums reign supreme among the floricultural plants due to the beauty and diversity of their long-lasting and colourful flowers. In view of the ease in management practices and ready availability of hybrids from private importers, Dendrobiums now occupy maximum area under orchid cultivation in the country (Rajeevan and Sobhana, 1993). Their contribution to international trade in horticultural plants is unmatched. They command a high demand and price as cut-flowers and potted plants and form the basis of a multi- million dollar horticultural industry in several countries of the world. But research work on the evaluation of commercial hybrids and varieties for suitability to our condition is very limited. So, the present study is aimed to identify the suitable varieties for growth and yield under greenhouse in the northern transitional tract of Karnataka, which is a leading cut flower growing belt next to Bangalore. Material and methods Studies on the performance of nine dendrobium orchid varieties were carried out under partially environment controlled greenhouse (i.e., Fan and pad polycarbonate covered greenhouse) at Hi-tech Horticultural unit, Main Agricultural Research Station, University of Agricultural Sciences, Dharwad during the year 2007-2009. The varieties used in the study were T 1 - Sonia -17, T 2 - Somark white, T 3 - Sripratum red, T 4 - Burana jade, T 5 - Burana fancy, T 6 - Manel, T 7 - Srisophol, T 8 - Emma white, T 9 - Medame uraiwan. The planting materials used were nine month old tissue cultured plants imported through a nursery man in India. These plantlets were planted in the earthen pots of size 6" x 4" and the potting media was prepared with a mixture of charcoal, broken brick and tile pieces in equal quantity. The experiment was conducted in completely randomized block design with three replications for each treatment. Each replication consisted of five plants. The irrigation was done twice a day for the plants during hot months and once a day during cool months. Besides, water was also sprinkled once a day to the floor for maintaining the temperature and humidity inside the greenhouse. During vegetative phase N, P and K at the ratio of 3:1:1 and during blooming phase at ratio of 1:2:2 were provided. Micronutrients were also applied at the concentration of 0.5 per cent twice a week. The temperature inside the greenhouse was maintained at 25 to 32°C during day and 21 to 25°C during night, while the relative humidity was maintained at 65 to 70 per cent. The fungicides Carbendazim (1.5 ml/l), Metalaxyl (1.5 g/l) and Mancozeb (3ml/l) were used to control fusarium wilt rot caused by phytophthora and leaf spot respectively. The selected materials were evaluated by recording observations on growth and yield parameters. The collected data were pooled and analysed statistically. *Part of M.Sc. (Agri.) thesis submitted by the first author to the University of Agricultural Sciences, Dharwad - 580 005, India