2017 ASHS Annual Conference

Bottom ash is thermal power plant waste material. Since bottom ash is inorganic and has good aeration with a proper particle size (1.5-3.0 mm), it may be used as an alternative substrate material for perlite. The objective of this study was to investigate how bottom ash-containing substrate affects germination and growth of four common bedding plants: Gomphrena globosa ‘Buddy Purple’, Catharanthus roseus ‘Pacifica Polka Dot’, Impatiens walleriana ‘Super Elfin Deep Pink’, and Petunia multiflora ‘Damask Blue’. Seeds of the four bedding plants were sown in 128-cell plug trays with the bottom ash-containing substrate mixed at 5 different ratios (coir dust : bottom ash at 10:0, 9:1, 8:2, 7:3, and 6:4) and a commercial germinating mix (BM2, Berger, Saint-Modeste, QC, Canada). All seeds or seedlings were grown in a greenhouse and well watered once a day. Germination rates of all four species were not affected by different substrate mixes, but days to germination of I. walleriana were a day longer in bottom ash-containing mixes than in a commercial germination mix. However, the effect of the bottom ash-containing substrate mixes on seedling growth were different by species. Most growth parameters of G. globosa and C. roseus seedlings were not significantly different across treatments, except for leaf growth. Leaf width of G. globosa grown with bottom ash-containing substrate mixes were lower than with a commercial germination mix. Leaf length and leaf area of C. roseus grown in a 100% coir dust were lower than with other substrate mixes, suggesting bottom ash could improve seedling growth by providing a better root environment for C. roseus. Unlike G. globosa and C. roseus, I. walleriana and P. multiflora seedlings had better growth in a commercial germination mix than bottom ash-containing substrate mixes. Total biomass of I. walleriana and P. multiflora seedlings grown on bottom ash-containing substrate was less than that on a commercial germination mix, indicating that the bottom ash-containing substrate might require further adjustment for I. walleriana and P. multiflora seedlings. A further study to investigate the performances of the four bedding plant seedlings with bottom ash containing germination mix in a trial bed is in progress. Growth and performance parameters of the four bedding plants will be presented to provide the potential suitability of bottom ash containing substrate mixes for growing bedding plants.