Height suppression of tomato plug seedlings by an environment friendly seed treatment of plant growth retardants
Experiments were conducted to investigate appropriate concentrations of plant growth retardants (PGRs) and duration of seed soaking in order to suppress hypocotyl length and plug seedling height of 2 tomato cultivars ( Lycopersicum esculentum Mill. cv. Seogeon and Seokwang). Daminozide (B-9), uniconazole (Sumagic) and ethephon (Florel) were used as PGRs. Seeds were first soaked in 15 ml PGR solutions in an environment controlled chamber (25°C) for 1, 3, or 5 days. Then seeds were washed in tap water and were dried in a 5°C chamber for 1 day. Finally, dried seeds were used in both a germination test in a chamber and a growing test in a greenhouse. Differences among cultivars in response were observed in germination and seedling growth. Although germination in petri dishes and seedling emergence in plug trays declined, suppression of hypocotyl length and seedling height was evident in uniconazole treatments in both cultivars, duration of seed soaking in PGRs solutions had greater influence than the concentration. Differences in percent germination and percent emergence were also observed as affected by PGRs. Uniconazole treatments suppressed hypocotyl length and seedling height very significantly. Seeds soaked in PGRs solutions germinated in petri dishes, but tended not to emerge well in plug trays.