Zinc, as a vital micronutrient for plant growth, holds a pivotal role within the processes of plant growth and development. It serves as an essential element throughout various stages of plant life cycles, significantly influencing physiological functions that underpin healthy plant morphology and metabolic activities. To explore the response pattern of Dendrobium officinale to zinc elements and to determine the optimal application concentration, this experiment set up four different external zinc solution concentrations, and used the plant group without applying external zinc solution as the control. This study employed physiological and biochemical experimental approaches to systematically analyze the variations in growth indices, physiological characteristics, and the key medicinal constituents of Dendrobium officinale under varying concentrations of zinc solution. By quantifying morphological changes, physiological parameter fluctuations, and bioactive compound profiles, the research elucidated the dose-dependent effects of zinc solutions on the plant’s development and secondary metabolism, providing a scientific basis for optimizing zinc application in its cultivation. The results show that the optimal Zn concentration for the growth of Dendrobium officinale is 400 mg/kg. It was also found that Dendrobium officinale responded well to low concentrations of Zn (200–400 mg/kg) in the early stage (7–21 days), while increasing the Zn concentration in the later growth stage (35 days) was beneficial to the growth of Dendrobium officinale. Among them, a level of 400 mg/kg showed a significant promoting effect on the secondary metabolites of Dendrobium officinale, increasing by 1.51% compared to the natural group (P < 0.05), with the increase in polysaccharides being the most significant at 16.78%. The concentrations of 200, 800 and 1600 mg/kg decreased by 38.34, 47.56 and 32.26% respectively compared to the natural group. Meanwhile, a concentration of 400 mg/kg promoted the accumulation of photosynthetic pigments and the operation of the osmotic regulation system in Dendrobium officinale. In the photosynthetic pigment accumulation, the promotion effects on Chla and Car were the most significant, increasing by 21.89% (P < 0.05) and 27.03% (P < 0.05) respectively as opposed to the natural group. Within the osmotic regulatory system, the promotion effect on soluble sugar at 35 days was more significant, increasing by 28.23% compared to the natural group. Regarding the antioxidant system, a concentration of 400 mg/kg showed a significant promoting effect on MDA at 35 days, increasing by 46.17% compared to the natural group. Moreover, the promoting effects of all concentrations on SOD, CAT and POD were not obvious, and the enzyme activities remained at a relatively low level. These research results provide scientific guidance for the artificial propagation of Dendrobium officinale.
Wu et al. (Sun,) studied this question.