Effects of pre-harvested N-(2-chloropyridin-4-yl)-N-phenylurea (CPPU) spraying on the improvement of flower quality of Dendrobium Sonia Earsakul

Abstract: Improvement of flower quality is a major concern which plays a part in the enhancement of the marketability of the Dendrobium cut flower. In this study, both synthetic cytokinins: N-(2-chloropyridin-4-yl)-N-phenylurea (CPPU) and N-6-benzyladenine (BA), were foliar sprayed at rates of: 1, 5 or 10 mg L^-1 and 100, 200 or 400 mg L^-1, respectively, on current pseudobulbs of the Dendrobium Sonia Earsakul with 45-50 cm in length. The treatments were applied thrice at fortnight intervals, prior to terminal bud initiation. The results revealed that an application of 10 mg L^-1 CPPU significantly increased the numbers of inflorescence per pseudobulb (from 1.1 to 1.7 flowers), and the number of flower on an inflorescence was increased from 12.2 to 13.8 flowers. The length and the diameter of flower inflorescence, having 10 mg L^-1 CPPU application, also increased from 49.4 cm to 55.1 cm, and 0.57 cm to 0.66 cm, respectively. In addition, the largest flower width and the highest fresh inflorescence weight were also obtained with application of 10 mg L^-1 CPPU treatment. Despite the application of BA, at 400 mg L^-1, enhancing the highest amount of flower counts of inflorescence (at 14.8 flowers), 33.3% of those inflorescence obtained at least one deformed flower. Overall, the results suggest that CPPU spray has a higher potential to elevate flowers, along with the inflorescence qualities of Dendrobium Sonia Earsakul. Furthermore, according to this study, CPPU has lower effects upon abnormal flower shapes, and their times of harvest.