2017 ASHS Annual Conference

A study was conducted to observe the effect of growth inhibition of tomato plug seedlings using temperature control to apply plug seedling production as environment-friendly. Tomato seeds (Solanum lycopersicum L. ‘Mini Chal’) were sown at 128-hole plug trays and were germinated for 7 days and then grown for 6 days in commercial plug seedling production greenhouse. And then these were put in closed-type plant production systems that were set with 180 μmol·m^-2·s^-1 PPF fluorescent lamp and 12/12h (light/dark) photoperiod. The treatments were ⅰ) +7 DIF (25/18°C, light/dark) (control), ⅱ) +7 DIF (25/18°C, light/dark) with diniconazole treatment, ⅲ) -7 DIF (18/25°C, light/dark), and ⅳ) temperature drop (TD, 14.5 and 26/19°C, light/dark). The TD was controlled as 14.5°C for 3 hours and 26°C for 9 hours at a day time, and 19°C for 12 hours at a night time. And average temperature in a whole day of all treatment was 21.5°C. Nutrient solution was supplied by the subirrigation as pH 6.5 and EC 1.5 dS·m^-1. The growth of tomato plug seedlings was measured at 37th day after sowing. Plant height, hypocotyl and internode length, leaf length and width, leaf area, and stem diameter were the greatest in the +7 DIF treatment. And these were significantly inhibited by the -7 DIF and diniconazole treatment. Root length was the longest in diniconazole treatment. No. of leaves and fresh and dry weight of shoot or root showed the highest value in the +7 DIF treatment. Compactness and dwarf rate were the highest in the diniconazole treatment. In the environment-friendly aspects, -7 DIF treatment using temperature control was the best achieved for growth inhibition of tomato plug seedlings, although the diniconazole treatment showed also great effect.