Combined Effects of Container Volume and Fertilizer Level on Plant Growth, Physiological Characteristics, and Nutrient Uptake of Vinca Plant (Catharanthus roseus)

The aim of our study was to investigate the interactive effects of container size and nutrient supply on plant growth, chlorophyll synthesis, transpiration, $CO_2$ assimilation, water use efficiency (WUE), and nutrient uptake of vinca plant (Catharanthus roseus). A complete experiment utilizing four concentrations of fertilizer and three volumes of containers was conducted. As the container size was increased, the plant height, leaf area, and dry weight of vinca significantly increased regardless of fertilizer level. The leaf area and dry weight of vinca were highly sensitive to the container size. However, the chlorophyll contents of vinca 20 days after the transplant significantly increased with decreasing container sizes and increasing fertilizer concentrations. Significant differences in transpiration and $CO_2$ assimilation occurred with the use of differentfertilizer solutions, but the highest values for transpiration and $CO_2$ assimilation were in plants grown in the 15 cm-diameter containers. The highest water use efficiency was observed in the plants grown in 10 cm-containers with 4 dS/m of fertilizer, and there were no significant differences in WUE values among container sizes with fertilizer concentrations of 0, 1, or 2 dS/m. No significant difference in nutrient uptake was observed among the fertilizer levels or among the container sizes. However, at a fertilizer concentration of 4 dS/m, the uptake of several nutrients, including N, P, K, Ca, Mg, B and Fe, was higher in small containers than in larger ones.