Work

Effects of Different Plant Growth Retardants on the Miniaturization of Nymphaea ‘Black Beauty’

Year: 2026

Type: article

Abstract: Tropical water lilies are a group of aquatic plants with high ornamental value and are widely favored in home gardening. However, most tropical water lily cultivars feature a large plant stature and vigorous spreading growth layout, making them unsuitable for cultivation in small containers. Therefore, developing miniaturization cultivation techniques for tropical water lilies in small containers is required. Plant growth retardants are effective in inducing plant dwarfing and overall miniaturization. In this study, the tropical water lily cultivar ‘Black Beauty’ was used as the experimental material to explore the effects of two plant growth retardants, chlormequat chloride (CCC) and paclobutrazol (PP333), on its growth and development, with the objective of screening optimal retardant types, application concentrations and treatment methods. The results showed that the growth rate of ‘Black Beauty’ slowed down under either CCC or PP333 treatment, and remained stable from day 21 to day 51. Compared with the control group, treated plants presented reduced crown spread, decreased leaf area and thickened leaves; the number of flowers and leaves declined slightly, and the key ornamental morphological traits (compact plant form, moderate leaf size, normal flowering) were maintained. PP333 exhibited a stronger dwarfing effect than CCC. When the plant growth retardants were dissolved in water for application, a 6-day treatment interval delivered better dwarfing efficacy than a 9-day interval. Among all treatments, 30 mg·L−1 PP333 applied at 6-day intervals achieved the optimal miniaturization effect. Following this treatment, the endogenous accumulation of chlorophyll, soluble protein and total sugar, together with the activity levels of antioxidant enzymes (SOD, POD, CAT), were markedly higher than those measured in the control and all other treatment groups, whereas the endogenous accumulation of malondialdehyde (MDA) decreased substantially. The contents of endogenous hormones IAA, GA3 and ZR in all treatment groups decreased with the increase in retardant concentration, whereas the ABA content showed an upward trend. The 30 mg·L−1 PP333 treatment applied every six days induced the minimal endogenous accumulation of IAA, GA3 and ZR, alongside the maximum endogenous ABA accumulation within plant tissues. For potted cultivation of ‘Black Beauty’ water lily, it is recommended to apply 30 mg·L−1 PP333 at 6-day intervals and use containers with an outer diameter of 30–35 cm.

Source: Horticulturae

DOI: 10.3390/horticulturae12070895