2014 ASHS Annual Conference

Growers generally use root media with high electrical conductivity (EC) for growing hot pepper plugs in Korea which often results in the suppression of early seedling growth. This study investigated the influence of varied leaching fractions during fertilization on changes in root substrate EC and seedling growth. Four different growing media formulations were used: peatmoss (PM)+pelite (PL) (7:3, v/v), PM+vermiculite (VM) (5:5), coir dust (CD)+PL (7:3), and CD+VM (5:5). Equal amounts of macronutrients (760 N, 265 P₂O₅, 596 K₂O, 480 CaO, 97.2 MgO and 78 S, in mg·L^-1) were incorporated into all root media as pre-plant fertilizers. Seeds were germinated in 50-cell (volume 33 cc) plastic trays and seedlings were fertilized once a week with 100 mg·L^-1 N at stage 2 and with 200 mg·L^-1 N using 20-10-20 or 14-0-14 fertilizers at stages 3 and 4. Leaching fraction (LF) (leachate volume/volume applied x 100) were controlled to 0, 50, 100, 150, or 200%. When LF were 0 and 0.5, seedlings 31 days after sowing grew well in PM+PL. But seedlings grew better in PM+VM or CD+VM than in PM+PL or CD+PL as LF were 1.0 or greater. After 31 days, PM+VM and CD+VM had a higher EC than PM+PL and CD+PL at the same LF. In all growing media, soil solution EC was reduced as LF was elevated. For best seedling growth, optimum LF ranges were 0.5 to 1.0 for PM+PL and CD+PL and 1.5 to 2.0 for both PM+VM and CD+VM.