Abstract

Liquid fertilizers have been used in Korean agriculture with great success, but exactly which types of manufacturing and application methods produce the highest rates of growth is not fully understood. Therefore, this experiment was conducted during 2018 in Suncheon, South Korea using fermentation, water and boiled water extracts and various application methods to determine which extracts were the best growth promotors of cucumber plants. Compared with the control, cucumber shoot fresh weight increased at the highest rates (2539%) when plants received treatments of fish fermentation extracts II and III, bone + fish I and V fermentation extracts, tomato fermentation extracts I and IV, onion fermentation extracts I and IV and sesame oil cake fermentation extracts I-VI. However, fermintation extracts made using red pepper leaf did not produce any significant growth promotion. The order of growth promotion effects is as follows: boiled water extract > water extract > fermentation extract. However, the highest rates of cucumber growth promotions were observed in plants treated with fermentation extracts at 3%, boiled water extracts at 1 and 3% and water extracts at 0.1, 0.5, 1.0 and 3.0%. Generally, plant height and shoot fresh weight of cucumber plants were not significantly different regardless of whether they received drenching or foliar applications. Rates of cucumber growth promotion were highest in plants treated with boiled water extracts 20 DAS whereas growth rates were similar in plants treated with fermentation and water extracts both 20 and 40 DAS. The photosynthetic efficiency and chlorophyll content of cucumber plants treated with various extracts may be not related to the cucumber growth promotion. Overall, fermentation extracts may be less suitable than extracts made using water and boiled water extraction. This is because water and boiled water extracts have both shorter production times than fermentation extracts as well as more consistant rates of growth promotion. Thus, the water and boiled water extracts tested in this study can be used for growth promotion in organic cucumber cultivation.