Increased relative humidity in the dry season during stomata opening promotes growth, leaf area, and biomass of CAM orchid: Dendrobium Sonia ‘Earsakul’

Abstract: Dendrobium cut-flower producers commonly employ sprinkler systems with high water consumption. Our study aimed to identify a more water-efficient irrigation method for orchids. Specifically, we investigated the optimal timing of water application during a day in the dry season, intending to minimize water usage. The research used a 3x2x2 completely randomized factorial design, factoring in the times of the day for irrigation (dawn, morning, and evening), the type of sprinkler head (standard or large vs. mini), and the duration of irrigation (6 minutes vs. 4 minutes). The study revealed that adjusting these factors could reduce the standard water volume used by 30 to 60% without negatively affecting the orchids’ growth or flower quality. Over five months of testing various irrigation techniques, metrics such as the height of the front pseudobulb, leaf count on the front pseudobulb, total leaf number per plant, pseudobulb count, and inflorescence quality (like length, number of flowers, and vase life) remained consistent across different methods. A notable discovery was that irrigating at either dawn or evening using a standard-sized sprinkler led to higher fresh and dry leaf weights and a greater leaf area than morning irrigation. Impressively, these results were observed even when the irrigation time was reduced to just 4 minutes, a 30% reduction from typical water usage. In summary, our research suggests that during the dry season, Dendrobium orchid growers can potentially reduce irrigation water usage by 30% without sacrificing the growth or quality of their plants.