Testing of new Bulgarian sunflower hybrids under the conditions of North-East Bulgaria

I. Productivity and traits related to productivity
G. Georgiev, P. Peevska, E. Penchev
Abstract. The investigation was carried out at Dobrudzha Agricultural Institute, General Toshevo during 2011 – 2012. It was aimed at determining the production potential and the values of some of the most important traits of four new Bulgarian sunflower candidate hybrids: Veleka, Vokil, Gabi and Divna, which were enlisted for official varietal testing in different foreign countries. The testing was done by sowing the hybrids on two dates, with three sowing densities. The first sowing date was normal for the conditions of North-East Bulgaria, when soil temperature is permanently above 8oC at 10 cm depth, the second date was one month later. The respective densities were 40000, 50000 and 60000 plants/ha. The following traits were investigated: seed yield (kg/ha), 1000 kernel weight (g), weight of seeds per plant (g), number of seeds per plant, percent of kernel (%), oil content (%). The results showed that the investigated factors – sowing date and crop density in combination with the year conditions during the investigation had significant effect on the productivity of sunflower and some important traits related to it. Hybrid Divna was with the highest seed yield per ha (4055 kg/ha) obtained at the highest crop density, followed by hybrid Vokil (seed yield 3936 kg/ha) obtained at the lowest crop density. Crop density and 1000 kernel weight were in reverse proportion at both sowing dates. The highest absolute weight was demonstrated by hybrid Divna – 62.5 g averaged for the two years at both sowing dates, followed by hybrid Vokil – 57.2 g. The later sowing date was related to decrease of the values of the character number of seeds per plant. At the higher crop densities, the weight of seeds per plant decreased during both years. Higher values were observed at the optimal sowing date during the entire period of investigation. The traits percent of kernel and oil content in seed showed the lowest variation, similar over years, which characterized these traits as stable and with low modification variability.