Effects of Growth Substrate on Greenhouse Gas Emissions from Three Annual Species

Previous work by these authors have quantified cumulative greenhouse gas (GHG) emissions for several woody and herbaceous perennial species, in interaction with several standard best management practices (container size, fertilizer application and irrigation delivery methods, and light level). In this study, the greenhouse production of three annual species [coleus (Solenostemon scutellarioides Thonn. ‘Redhead'), vinca (Catharanthus roseus L. ‘Cooler Grape'), and impatiens (Impatiens walleriana Hook. f. ‘Super Elfin XP White')] was evaluated in three substrates [80:20 peat:perlite, 80:20 peat:WholeTree (a whole pine tree-based substrate), 60:40 peat:WholeTree]. Emissions of CO2, N2O and CH4 were collected over a period of 52 days. Without regard to media, coleus had the highest cumulative CO2 efflux (statistically similar to vinca), due to its increased size in comparison with both vinca and impatiens. Without regard to species, plant-pot systems using the highest proportion of WholeTree (40%) had numerically the most cumulative CO2 efflux (statistically similar to those containing only 20% WholeTree). No differences were observed for the main effect of species or media for N2O or CH4. Results suggest that using a more sustainable high wood fiber substrate in similar proportions to that of perlite in an industry standard mix (20%) could yield similarly sized plants with no negative impact on GHG emissions. Index words: alternative substrate, WholeTree, carbon sequestration, carbon dioxide, nitrous oxide, methane, global climate change. Species used in this study: ‘Redhead' coleus, Solenostemon scutellarioides Thonn. ‘Redhead'; ‘Cooler Grape' vinca, Catharanthus roseus L. ‘Cooler Grape'; ‘Super Elfin XP White' impatiens, Impatiens walleriana Hook. f. ‘Super Elfin XP White'.