Honors Program


Document Type


Date of this Version

Spring 3-5-2022


Iradukunda, M., Read, P.. 2022. Influence of Fertilizer Rate on Swollen Stem Formation (“Bulbing”) and Vitamin C Content in Different Kohlrabi Cultivars. Undergraduate Honors Thesis. University of Nebraska-Lincoln.


Copyright Mark Iradukunda, Paul E. Read 2022.


Kohlrabi (Brassica oleracea Gongylodes Group) is a vegetable crop found in the Brassicaceae, and it is rich in antioxidants such as vitamin C. Vitamin C helps in oxidative damage repair and strengthens the immune system, so exploring vitamin C sources may contribute to improving human health. The objective of this study was to determine the effect of different fertilizer rates on kohlrabi yield, in terms of the swollen stem and the vitamin C content, and if those effects are similar in different kohlrabi cultivars. In this greenhouse study, we fertilized four potted kohlrabi cultivars with a common water-soluble greenhouse fertilizer (Peters Professional 20-10-20) at zero, one-half recommended, recommended, and double recommended rates where the recommended rate plants received 308mg of fertilizer each week in irrigation water. Results showed that plants of all cultivars that received the double rate of fertilizer had the highest yield with a fresh swollen stem weight of 448 g, while plants that received no fertilizer had the lowest yield with 21.2 g and they were visibly nutrient deficient. An increase in fertilizer rate increased the vitamin C content where the total vitamin C per swollen stem averaged 6853 mg for the double rate and 846 mg for the zero rate. The results from this study will help farmers to effectively apply fertilizers to increase kohlrabi yields and vitamin C content while doing less harm to the environment caused by excessive fertilizing. In return, this will help people to get more vitamin C sources which may improve their health.