Abstract:To promote the use of garden waste and optimize the cultivation substrate for Bougainvillea, this study investigated the feasibility of using garden waste compost products of different particle sizes to replace traditional high-cost or non-renewable substrate materials. Three substrate treatments, T1, T2, and T3, were established by blending field soil, vermicompost, and compost products of three particle size fractions in different volume ratios, with a conventional horticultural substrate serving as the control. The physicochemical properties of the substrates and the new shoot growth, flower number, and root system development of Bougainvillea glabra ‘Rosa’were measured. The results showed that compared to the control, all treatments significantly reduced substrate bulk density and increased organic matter content. Among them, the T2 treatment exhibited the highest total porosity and water-holding porosity, indicating the best water retention capacity. The T3 treatment had the lowest bulk density, suggesting optimal aeration. Regarding plant growth promotion, the T2 treatment performed best, with new shoot length, flower number, and root dry weight and length after 40 days of controlled watering being significantly superior to those of other treatments. In conclusion, the T2 formulation, primarily composed of a 5~20 mm particle size compost product, best balances the water, air, and nutrient relations of the substrate, effectively promoting the growth and flowering of Bougainvillea. It represents a valuable optimized substrate formula worthy of promotion.
