The sunflower hybrid Velko was developed at Dobrudzha Agricultural Institute – General Toshevo (DAI). This is a male sterile two-linear hybrid derived through the method of inter-linear hybridization. The mother component is line 3607 which possesses cytoplasmic male sterility, and the father component is line 105R, a branched fertility restorer. Both parental forms have excellent general and specific combining ability. The Velko hybrid is mid-early, with a 115-118-day growing season, plant height – 165-170 cm, and head diameter – 19-21 cm. The absolute weight of the seeds is 60-65 g, and the oil percentage – 47-48%. The kernels in the seed reach up to 73-74%. The weight of seeds per plant is within the range of 75-85 g, and the number of seeds per plant is 1,170-1,300. The duration of flowering is 12-14 days. The new hybrid went through a three-year testing in the breeding fields of DAI according to a scheme approved for that crop. In a competitive varietal trial in the first two years it exceeded the average standard for seed yield by 13.7% and 10.6%, respectively, and during the third year of testing in a unified competitive varietal trial the exceeding was by 5 %. The maximum yield obtained was 4,183 kg/ha, with 1,970 kg/ha of oil yield, while the oil content reached 48.4%. The hybrid is resistant to the economically important diseases and to the parasite broomrape. In 2011 Velko was submitted for official testing within the structures of the Romanian Varietal Commission at 10 locations. The new hybrid exceeded the Romanian standard by 9.0% for seed yield during the three years of the official testing. The maximum yield obtained per ha was 4,960 kg and the average yield for the three years was 3,578 kg/ha. The Velko hybrid was officially registered in Romania with Certificate No 1380/23.02.2015 and was included in the European Catalogue of Field and Vegetable Crop Varieties.
Characterization of a new Bulgarian sunflower hybrid - Velko