Suitability of Whole Pine Tree Substrates for Seed Propagation
Wood-based substrates are a viable option for producing crops in containers, but seed propagation in such substrates has not been sufficiently examined. Seed germination and seedling development in processed whole pine tree (Pinus taeda L.) substrates were evaluated using the Phytotoxkit and seedling growth tests. Substrates compared using the Phytotoxkit included a reference soil, aged (WPTA) and fresh (WPTF) whole pine tree, aged (PNA) and fresh (PNF) pine needles, pine bark (PB), peat moss (PM), and saline pine bark (SPB). Substrates evaluated using the seedling growth test included WPTA, WPTF, PB, and a peat-lite (PL) substrate. Seed germination percentage and total root length were evaluated for garden cress (Lepidium sativum L.), white mustard (Sinapis alba L.), and sorghum [Sorghum bicolor (L.) Moench] in repeated Phytotoxkit experiments (2010 and 2011). Seed germination percentage was lowest for garden cress in PNF, but similar among all substrates for white mustard and sorghum. Total root length was similar or greater in WPTA compared with PM for all species. Seedling emergence percentage and total root length were evaluated for lettuce (Lactuca sativa L.), tomato (Solanum lycopersicum L.), and oat (Avena sativa L.) in repeated seedling growth experiments (2010 and 2011). Seedling emergence percentage varied among substrates and was substantially greater in PL and WPTA compared with PB and WPTF in 2010. Total root length was greatest in PL compared to the other substrates for all species in both years. In addition, PL had significantly lower air space and greater container capacity compared with the other substrates.