S06 - Session P16 - Substrate stratification influences root architecture in containerized production

Authors: Jeb Fields *, Kristopher Criscione

Soilless substrates are utilized in containerized nurseries to produce a salable crop that provides optimal growing conditions for plants. Traditionally, bark-based substrates are used due to their reliability and safety in case of overwatering. However, due to relatively low water holding capacity of traditional soilless substrate systems frequent irrigations are required to maintain optimal conditions and sustain plant growth. To mitigate the inefficient conventional substrate systems, an innovative substrate management strategy has begun to gain interest. Soilless substrate stratification entails the vertical stacking of unique soilless substrates within a container. The goal of this research was to compare the separate textural components tension and moisture content fluctuations to the entire stratified and non-stratified profiles. Moreover, the authors sought to determine how root exploration is influenced by stratified and non-stratified systems and compare if roots grown in entire systems filled with individual components (i.e., fine bark or coarse bark) grow similarly when in stratified systems. This goal was accomplished by growing Hibiscus acetosella 'Panama Red' liners in four substrate treatments 1) non-stratified system filled uniformly with conventional pine bark 2) stratified system that consisted of fine bark ( < 6.3 mm) layered over coarse bark ( > 6.3 mm) 3) fine bark and 4) coarse bark. Water potential of each strata was continually monitored through tensiometers affixed in each strata and additional sensors recorded volumetric water content. Growth and crop quality was monitored in each treatment. Upon harvest, root systems were assessed and washed of debris. Roots architecture was then analyzed through a root imaging software.