Seed enhancements to improve spinach germination

Rapid, synchronized, and high percentage of germination is required for com mercial spinach (Spinacia oleracea L.) production using hydroponic techniqu es. Seed treatments examined to improve seed germination were: 1) decoating ; 2) leaching in water; and 3) soaking seeds for 4 hours in 0.5% NaOCl, lea ching for 15 hours in water, and sowing in 0.3% H2O2 (this treatment will b e referred to as NaOCl/H2O2). Germination studies were conducted on four cu ltivars at a constant 18 degreesC (optimal) or 30 degreesC (inhibitory). At 18 degreesC, germination rate (T-50) was maximized by both hydration treat ments, but uniformity of germination (T-deltad) was greatest for decoated s eeds; final germination was greater than or equal to9% for all treatments. At 30 degreesC, decoating resulted in greatest uniformity of germination. T he NaOCl/H2O2 treatment resulted in highest germination (94%) at the high t emperature, whereas decoating was least effective (69%). Reduced germinatio n of decoated seeds was attributed to atypical germinants. Cultivars differ ed in response to the treatments at both temperatures. Component analysis o f the NaOCl/H2O2 treatment was studied with two slow-to-germinate cultivars . Treatment with H2O2, with or without NaOCl, improved the rate, uniformity , and percentage of germination of seeds of both cultivars, but NaOCl alone did not. Pericarp removal or pericarp removal plus NaOCl H2O2 treatments r educed variability in germination time and enhanced speed of germination at 30 degreesC, but decoating produced a higher percentage of atypical seedli ngs than did other treatments. Therefore, the NaOCl/H2O2 treatment is recom mended for growers who are unable to maintain cool germination temperatures and/or cannot afford the costs associated with cooling. If growers can mai ntain a germination temperature of approximate to 18 degreesC, decoated see ds are preferable, based on the high uniformity of germination.