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

This research was conducted to determine the influence of post-planting fertilizer (PPF) concentrations the growth of hot pepper (Capsicum annuum L. cv. Nokkwang) seedlings when the nutrient solution was applied by sub-irrigation. Two different root media were formulated by mixing peat moss (grade 0 to 6 mm, PM06) and perlite (grade 2 to 5 mm, PE3) or peat moss (grade 0 to 10 mm, PM010) and PE3 with the ratio of 7:3 (v/v). The media were used to fill the 72- cell plug trays (cell volume 72 mL) and seeds were sown. After germination, the seedlings were grown in the growth chamber. The application of 13-2-13, 15-0-15, and 20-9-20 commercial analysis (N-P₂O₅-K₂O) fertilizers in sequence began at the seedling stage 2 (cotyledon emergence) and the feeding solution nutrient concentrations were varied in three different treatments with 25 mg.L^-1 N level increments each week: PPF 1 (0-100 mg.L^-1), PPF 2 (25-125 mg.L^-1), and PPF 3 (50-150 mg. L-1). The seedling trays were sub-irrigated with the fertilizer solution when the weight of each tray was reduced to 40 to 50% from container capacity. After 1, 2, 4 and 5 weeks after seed sowing, pH, EC and macronutrient element concentrations were analyzed and the growth of seedlings were measured 5 weeks after sowing. The fresh and dry weights of the seedling were heavier in the treatments of higher EC among the fertilization PPF 1 and 2, compared to those grown in PPF 3. The upward movement of fertilizer solution by capillary action resulted in the increase in electrical conductivity (EC) in the upper part of root substrate when the EC was measured separately for the upper, middle, and bottom portion of the growing media. The highest EC in the upper part of root media among all treatments was 2.7 dS.m^-1, suggesting the leaching of nutrients by overhead irrigation is necessary when substrate EC rise is a concern. The changes of Na⁺, NO₃^--N and K⁺ concentrations in root substrate during seedling culture had a similar trend as changes in EC. The macronutrient concentrations of Ca²⁺, Mg²⁺ and PO₄^3--P were lowered in the treatments of low or high substrate pH. In summary, the use of 13-2-13, 15-0-15 and 20-9-20 fertilizers in sequence and gradual elevation of nutrient solution N concentrations from 25 to 125 mg.L^-1 during sub-irrigation were satisfactory for growing pepper seedlings using the root substrate with 77.9% container capacity.