Achieving Optimal Irrigation Efficiency for Growing Dendrobium Sonia ‘Earsakul (Orchidaceae): Comparing Coconut Husk Bed and Cement Block

Abstract

Thailand ranks first in the world for orchid and cut flower production. In 2018, sales were about 2,100 million baht. Thailand’s Dendrobium orchid growers most commonly use a coconut husk; however, the bed decays and must be replaced every five years. Moreover, orchid farms use up to 10 mm per day to irrigate their orchids. This study undertook determine the most efficient water irrigation rate and to compare a new material (cement block) and with the traditional coconut husk. This was done by using different incremental water irrigation rates and comparing various growth parameters of the orchids grown in traditional coconut husk and cement block, as they reached maturity (18 months of age). Comparable planting materials were used to grow orchids in the two plant types, coconut husk and cement block, and separate plantings were irrigated using different watering rates (3, 4, 5, 6 and 10 mm per day) for 5 months. A traditional coconut husk with a watering rate of 6 mm per day was used as the control. A comparison of the growth parameters (pseudobulb, leaves, leaf thickness, and leaf length) revealed no significant different each of the alternative watering rates between the coconut husk, the cement block, and the control. However, the leaf width, total flower, and opened flower observed in plants grown in the coconut husk planting media at the 3 mm per day irrigation rate were less than the control. Likewise, the orchids’ leaf width, total flower, and opened flower for the cement and the control showed no significant difference at the 5 and 10 mm per day watering rate. However, at 6 mm per day watering rate, the orchids grown in the cement block had the biggest size of orchid flower. In conclusion, growth parameters revealed that a 5 mm per day watering rate using a coconut husk achieved the best flower qualities, equivalent to the control.