Study on poinsettia (Euphorbia pulcherrima Willd.) production by substrate culture

Growth of 4 poinsettia (Euphorbia pulcherrima Willd.) cultivars in substrate culture method were influenced by cultivars and substrate used. During vegetative growth, the average height canopy width, leaf area and shoot biomass of Lilo red were greater than the others. By using the paddy husk charcoal mixed with coarse sand (2:1 by volume) as a substrate, plants were significantly higher in average height and canopy width. At flowering, the average height of Lilo red planted in the paddy husk charcoal mixed with coarse sand (2:1) and Angelika pink planted in the coir dust mixed with coarse sand (2:1) were significantly greater than other treatments (62.0 cm and 61.9 cm respectively), but there were no different in the average of canoppy width, shoot no., leaf area and shoot biomass between cultivars and substrate in this stage. The color of Lilo red's bract was detected faster than other cultivars (76.1 days) whereas the bracts of Subjibi red reached full bloom stage faster than the others (94.2 days). By using the coir dust mixed media, the bract development reached the complete stage (100.9 days) sooner than those grown in the paddy husk charcoal mixed media (105.2 days). Lilo red had the greatest bract no. per inflorescence (27.8 bracts) and cyathia no. per inflorescence (25.9 cyathia), Subjibi red had the greatest bract width (8.28 cm) and Lemon drop had the greatest bract length (12.4 cm). The average nutrient solution given to each pot was 218.2 ml per day, The average fertilizer used for each pot was 0.51 gram per day. The nutrient leachate from the paddy husk chacoal mixed with coarse sand (2:1) and the coir dust mixed with coarse sand (2:1) were 20.4 percent and 29.1 percent respectively. Angelika pink and Subjibi red were susceptible to abnormal elongated growth disease, the symptoms including lesions at leaves and stems and abnormal elongated stems, whereas none of such symptoms were detected in Lemon drop and Lilo red. By using tissue transplanting method, intact plants carrying the disease were incubated in PDA agar and Fusarium sp. colonies were found 70.0 percent from stem tissue incubation and 74.0 percent from leaf tissue incubation, respectively.