Effects of the amount of potassium and its supply strategy on fruit production of tomato plants [Lycopersicon esculentum] grown in hydroponics

Potassium absorption, growth of plants and fruits, fruit quality and content of macro-elements in plant organs were examined in tomato plants (Lycopersicon esculentum cv. 'Saturn') with two trusses, grown in NFT using nutrient solutions containing different concentrations of potassium during the period of fruit growth. Amount of potassium absorbed by fruits is positively and linearly related to total fruit fresh weight, and fruit yield increased with increasing absorption of potassium by the plants up to above 7000 mg/plant. In plants that absorbed a large amount of potassium, however, the increase in fruit fresh weight was diminished. The influence of the amount and frequency of potassium supply during the different period of fruit growth on fruit production were examined in the tomato plants grown using the nutrient solution containing the same total amount of potassium; it became evident that fruit yield, soluble solid content and titratable acidity were not affected and the possibility of decreasing the incidence of gold speck fruits (GS) was suggested by the quantitative management method of potassium.