Research on night-break effects of lighting from specialized LED on growth and flowering control of chrysanthemum (Chrysanthemum indicum L.) on a hydroponic system

Abstract

    The study aimed to evaluate the effect of night break, including light duration and timing, and the suitable type of LED light with specialized spectra for high efficiency in flowering, promoting growth and enhancing flower quality of chrysanthemum plants cultivated in a recirculating hydroponic system. The experiments were conducted in a completely randomized design (CRD) with three replications within a greenhouse. Our results indicated that the optimal light duration was 90 minutes per night, with light applied at 3:00 AM daily, continuously for 40 nights/crop cycle. The light treatment facilitated plant growth (plant height: 49.75 cm, leaf number: 29.08) and yielded high-quality flowers (flower diameter: 61.32 mm, flower longevity: 19 days), while effectively delaying flowering by 27.9 days compared to the non-night break control. Furthermore, our study indicated that, LED light with a spectrum of 660 nm, supplemented with a red light at 730 nm, proposed and manufactured by the Advanced Institute of Agricultural Biology Research and Development, Nguyen Tat Thanh University, as an economically efficient light source for the night break process to control flowering in chrysanthemum plants.