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In this study, the effect of supplying volume and frequency of a nutrient solution consisted with NO 3 -N 4.6, NH 4 -N 3.4, PO 4 -P 3, K 3, Ca 4.6 and Mg 2.2mmol•L -1 on growth and fruit quality of 'Duke' blueberry was investigated. Three years old 'Duke' blueberry bushes cultivated in containers (60 × 80 × 40cm) filled with 130L peat moss and 40L pearlite (v/v) were selected for the experiment. The growth containers were mulched with sawdust. Two different volumes (4L and 8L) of nutrient solution was tested at three different supplying frequencies (one time, two times, and three times) per week and the drainage quality of nutrient solution and fruit quality of 'Duke' blueberry was evaluated. The optimal drainage rate for the vegetable cultivation is known to be 20-30%. The results revealed that the average drainage rates of 27% and 29% for the nutrient solution supplied in 'Duke' blueberry growth medium at 4L, 2 times/7 days and 4L, 3 times/7days, respectively. The highest shoot diameter (4.2mm) and shoot length (31cm) of 'Duke' blueberry was recorded with the 8L of nutrient solution supplied at 3 times per 7 days. According to the analysis of inorganic components in the drainage of nutrient solution, there was a tendency of absorbing nitrogen at the early stage of growth. The supplying volume and frequency of nutrient solution was not significantly affected on 'Duke' blueberry fruit weight, soluble solids content, and titratable acidity. The highest yield per bush (2.7kg) was recorded for the nutrient solution supplied with 4L at three times per 7 days, while the 4L nutrient solution supplied at one time per 7 days resulted the lowest yield of 1.4kg per bush. Consequently, the tested nutrient solution can be applied for the 'Duke' blueberry bushes with the volume of 4L at three times per week for the better crop growth.

This experiment was conducted to understand nutrient uptake of container-grown highbush blueberries in plastic film house. In March 2013, one-year-old 'Duke' was planted in a 180-L container mixed with peatmoss (130 L) and perlite (40 L), and hydroponic solution was supplied (fertilization) or not (non-fertilization) until October 2020. Hydroponic solution consisted of NO 3 -N 4.6, NH 4 -N 3.4, PO 4 -P 3.3, K 3, Ca 4.6, and Mg 2.2 mmol L -1 and the non-fertilization was supplied with only underground water. In October 2020, total dry weight of a blueberry increased 1.5-fold more in the fertilization than in the non-fertilization. Dry weight and inorganic nutrient content were the greatest in root than in leaf, shoot, old branch, and cane, indicating importance of root as a reserve storage organ. Fertilization increased dry weight by 2-fold and inorganic nutrient contents of root by 2.2 -2.6-fold. Total content of each nutrient in a bush increased 1.8 -2.2-fold more by the fertilization. In non-fertilized treatment, maintaining dry weight and nutrient contents for 8 years indicated that plants absorbed the nutrients to some extent through mineralization of peatmoss medium and underground water.

This experiment was conducted to evaluate the usefullness of cocopeat as a soil medium in blueberry cultivation. Two-year-old northern highbush blueberry 'Duke' and southern highbush blueberry 'Spring High' were planted in soil medium mixed with peatmoss (soil:peatmoss (v/v), 1:1) or cocopeat (soil:cocopeat (v/v), 1:1) in open fields in 2019. Soil pH measured in 2020 and 2021 ranged from 4.2 to 5.0 in peatmoss and 5.2 to 5.8 in cocopeat medium, indicating peatmoss has more suitable pH for blueberry growth. Two years soil analyses indicated that peatmoss medium tended to contain a higher available P 2 O 5 content and lower exchangeable cations compared with those of cocopeat. In 2021, peatmoss medium significantly increased the number of shoots per bush, by 16% for 'Duke' and 92% for 'Spring High' compared with the cocopeat. Bushes from peatmoss medium produced yield 1.9-to 2.7-fold higher for two years in 'Duke' and 1.4-to 1.8-fold higher in 'Spring High' compared with respective yields from cocopeat. Fruit characteristics for two years were not consistently affected by different soil media, except that the acidity was slightly higher in peatmoss. The results suggested that since the better bush growth from peatmoss medium resulted mainly from lower soil pH, the use of cocopeat as a soil medium should be followed by pH adjustment.