Effect of Organic Nutrient Sources on the Growth and Fruit Yield of Black Chokeberry Trees

There is limited information currently available on the nutritional effects of the by-products of starfish and oil cake applied to horticultural crops. This study investigated the effects of oil cake and starfish fertilizers on the performance and fruit yield of organic black chokeberry (Aronia melanocarpa (Michx.) Elliot) in South Korea between 2020 (year 1) and 2021 (year 2). The treatments included the use of 0% pelletized oil cake with 100-fold diluted starfish (0OC+SF), 33% oil cake with starfish (33OC+SF), 66% oil cake with starfish (66OC+SF), and 100% oil cake (100OC). The soil electrical conductivity, organic matter, and concentrations of total nitrogen (T-N) and P2O5 were found to be not significantly different between the treatment plots in years 1 and 2. The 66OC+SF and 100OC treatments increased foliar T-N concentrations in both years. Seasonal SPAD in the leaves increased in the 66OC+SF and 100OC treated bushes in August of year 1 and in June and September of year 2. The 0OC+SF treatment lowered the canopy volume, number of canes, and the sum of cane diameters, followed by 33OC+SF, which decreased the shoot and leaf growth but received a high light intensity from the canopy in year 2. The 66OC+SF treatment increased the fruit yield in both years, followed by the 100OC treatment. The total dry weight was determined to be greatest for the 100OC treatment bushes in year 2, while the highest fruit yield efficiency was observed for the 66OC+SF bushes. The 0OC treatment reduced the fruit length and diameter, the fresh weight, and the soluble solid content but increased the fruit surface color of lightness and yellowing. The 66OC+SF treatment was determined to be the optimum application source for moderately high leaf T-N and SPAD levels, medium-sized production of bushes, and overall high fruit productivity of black chokeberry crops.