Evaluation of Quantitative and Qualitative Characteristics of Long Pepper as Affected by Different Potassium Concentrations in Soilless Culture

Pepper has high nutritional values as a vegetable crop. Different chemical compounds are involved in this trait. Plant nutrition and the ratio of nutrient elements are important for qualitative and quantitative production of crops. In this regard، potassium is one of the most important elements in quality and physiology of horticultural crops، and it is desirable to have always high concentration of potassium in fruits. In this study، the role of different potassium concentrations in nutrient solution on quality factors of long pepper (Capsicum annuum var crusador) was investigated in hydroponics system. The treatments were concentrations of 150، 235، 300، 400، and 500 mg K/L from potassium nitrate and/or potassium sulfate sources. The concentration of 235 mg/L was considered as control in this study. The results showed that the highest yield was obtained from 300 mg K/L treatment. While there was an increasing trend in fruit length and diameter with increasing potassium concentrations، the differences were not significant. Some biochemical quality factors were، however، affected by potassium levels، although there was no significant difference for fruit pH، 500 mg K/L treatment showed significantly higher titratable acidity compared to other treatments. The amount of vitamin C and soluble solids were significantly higher in 500 and 400 mg K/L treatments، respectively، compared to the other treatments. These results indicated that this cultivar of pepper required more potassium for high quality.