Department of Horticulture, Faculty of Viticulture and Horticulture, Agricultural University-Plovdiv, 12 “Mendeleev” Str., 4000 Plovdiv, Bulgaria
(Manuscript received 15 June 2019; accepted for publication 31 July 2019)
Abstract. The main aim of the present study was to establish the changes in the generative development of carrots seed stalk during seed production depending on the frequency and level of fertilization. Two times of fertilization were tested: once – phosphorus and potassium were applied in autumn and nitrogen in transplanting time, and twice – half of phosphorus and potassium in the autumn, while the other half and nitrogen in soil in spring and half nitrogen in flowering. The number of umbels in the branches of I, II and III orders was determined. The average number of constituent units of one umbel from the central umbel and from umbels of different orders, as well as the average number of flowers in one umbel were established. Differences between variants were identified. Fertilization has a significant impact on the number of umbels and flowers. The number of flowers in the central umbel and those of the other umbels was the highest in one-time fertilization with N90P90K200/ha, while in two-times – with N50P190K200/ha.