Particle Size of Volcanic Tuff Improves Shoot Growth and Flower Quality of Asiatic Hybrid Lily Using Soilless Culture

Abstract

Soilless substrates enhance growing environment, nutrient content, and water quality in the growing medium. The objective of this study was to assess the influence of substrate particle size on growth and flower quality (flower number and length per plant) of two asiatic hybrid lily (Lilium ×elegans) cultivars Fangio and Ercolano. Plants were grown in 12-L pot under greenhouse conditions. Five grades of particle-size substrate, consisting of granulated volcanic material (tuff) were used as treatments. These sizes were 0 to 2, 0 to 4, 0 to 8, 2 to 4, and 4 to 8 mm. Fertigation was applied daily. Plant morphology, physiology, and flower quality were determined during flowering stage. Treatments of 2 to 4- and 4 to 8-mm tuff had lower water holding capacity (WHC), bulk density, electrical conductivity (EC), and pH compared with 0 to 2- and 0 to 4-mm tuff. In addition, plant height, leaf area, and flower quality of ‘Fangio’ were higher compared with ‘Ercolano’. Chlorophyll content and fluorescence were similar among all treatments. Leaf fresh weight, leaf area, shoot dry weight, root dry weight, and flower quality were higher in sizes of 0 to 4-, 2 to 4-, and 4 to 8-mm than 0 to 2-mm tuff, especially those from ‘Fangio’. The 0 to 4-mm substrate had an optimal and consistent flower quality results in both cultivars when compared with other tuff sizes. Overall, the results presented here suggest that using 0 to 4-mm tuff substrate holds promise for improving growth and flower quality of asiatic hybrid lily grown under soilless culture.