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

Increasing soil salinity in a plastic film greenhouse limits crop production. Chelating agents can form a complex with polyvalent cations, influencing the availability and mobility of salts in soil. To investigate the effect of a chelating agent on growth and nutrient uptake of crops, we cultivated watermelons (Citrullus lanatus) in a plastic film greenhouse where the soil was saline. The chelating agent diethylene triamine pentaacetic acid (DTPA) was applied eight times during the growing season, with total application rates of 0, 0.18, 0.3, 0.6, and 1.8 kg DTPA/10a. DTPA application at the rate of 0.6 kg/10a significantly (p < 0.05) increased aboveground growth of watermelons compared with no application (0 kg DTPA/10a), with yield and sugar content of the watermelons increasing 7.7 and 7.6%, respectively. However, further DTPA application at the rate of 1.8 kg/10a did not increase productivity of watermelons. Nutrient contents of the plant also increased with the increasing yield of watermelons. The increase in K content of the plant (45.9%) was apparent compared with that in Ca content of the plant (27.6%). Soil salinity at the rate of 0.6 kg DTPA/10a significantly (p < 0.05) decreased by 19.9% compared with no application, as a result of nutrient uptake by plants, and the exchangeable K⁺ in soil decreased markedly compared with the exchangeable Ca²⁺. These results suggested that DTPA treatment of saline soil in a plastic film greenhouse reduced salt stress of plants, relieved nutrient imbalance through increasing plant uptake of monovalent cations in the multivalent-cation-abundant soil, and consequently increased crop growth.