Plant Growth and Partitioning of Dry Matter and Inorganic Elements in Highbush Blueberry (Vaccinium corymbosum L.) ‘Scintilla’ Grown with Different N and K Compositions of Nutrient Solution in Heated Greenhouse Cultivation

This study was conducted to improve a nutrient solution composition to grow southern highbush blueberry cultivar ‘Scintilla’ in a pot in the heated greenhouse cultivation. From September in 2020 to late May (40 days after harvest) in 2022, young blueberry plants were supplied with different compositions of nutrient solution, a 25% increase (NK increase) and a 25% decrease (NK decrease) in N and K concentrations, compared with a nutrient solution for the unheated greenhouse cultivation (control). Fruit size was not consistently affected by the nutrient compositions in the two seasons. Fruit yield in both 2021 and 2022 increased by 14 - 22% for the NK increase, but decreased by 13 - 59% for the NK decrease, compared with the control. Total shoot length per plant was 28 - 56% longer for the NK increase than the control, while it was 33 - 47% shorter for the NK decrease. Total dry weight per plant increased by 25% for the NK increase, especially 2.4-fold greater in root, which contrasted with a 17% reduction for the NK decrease. 7.2% and 51.2% of the total dry weight of a plant were partitioned to root and fruit for the control, respectively. The root partitioning of the dry weight increased to 14.1% for the NK increase, while the fruit partitioning increased to 54.1% for the NK decrease. The NK increase resulted in 49% and 30% increases in the total N and K contents per plant, respectively, compared with those of the control, while the NK decrease caused 41% and 21% reduction in the respective total content. When N and K increased in the nutrient solution, the root partitioning increased with lower leaf and fruit partitioning of inorganic elements, compared with the control. However, the root partitioning decreased with higher fruit partitioning for the NK decrease. The result indicated that the NK 25% increase of nutrient solution helps promote root growth with higher nutrient absorption, increasing the whole plant growth and the yield.