Horticultural Science and Technology 원예과학기술지 ISSN:1226-8763(Print) 2465-8588(Online)

This study investigated the effect of pre-planting nitrogen (N) fertilization levels added to a soilless root medium on the growth of ̒Dotaerang Dia̓ tomato seedlings. The N levels were varied for a total of 7 treatments: 0, 100, 250, 500, 750, 1,000, or 1,500 mg·L^-1. The pH of the root media gradually rose in all treatments as the seedlings grew; however, the differences in the pH were not significant among the treatments. The electrical conductivity (EC) of the root media was significantly different among the treatments from sowing to week three, then drastically decreased after week four, which diminished the differences in the EC among the treatments. At week six, plant height, leaf length, leaf width, number of leaves, and fresh and dry weights of the shoot were highest for the treatment with 500 mg·L^-1 N. In contrast, the treatment with 1,500 mg·L^-1 N had the lowest results for all growth measurements. The fresh weight was 67% heavier in the 500 mg·L^-1 N treatment compared to the 1,500 mg·L^-1 N treatment. The total N content in the tissues was lowest in the treatment with 0 mg·L^-1 N and highest in the treatment with 1,000 mg·L^-1 N. The contents of calcium (Ca), magnesium (Mg), and metal micronutrients in the tissues were highest in the 250 mg·L^-1 N treatment. A previous study demonstrated that adjusting the fertilization level to promote growth to over 90% of the maximum growth is a good strategy for lowering production costs and preventing damage due to excessive fertilizer absorption by crops. Our results indicated that the optimal pre-planting N fertilization level for tomato plug seedlings should be lower than 500 mg·L^-1 and the optimum tissue N contents should be around 3.21% to 4.60%.