Abstract. The experiment was set up using a block method in 4 replications after a wheat predecessor in the fields of two different ecological regions – Thrace (Plovdiv region) and Dobrudja (Dobrich region), Bulgaria. Six sunflower hybrids were studied – P64LP170, breeded in Corteva, USA as a standart, and Bulgarian hybrids Dalena, Deveda, Enigma, Krasela and Sunny, breeded at the Dobruja Agricultural Institute - General Toshevo. For the purpose of the study, the occurrence of the main phenological phases have been recorded: sowing (V0), germination (VE), second pair of leaves (V2), the fourth pair of leaves (V4), budding (R1),beginning of flowering (R5), end of flowering (R6) and ripening(R9). Depending on the dates of the phenological phases, the duration of the interphase periods is calculated. Each of the phenological phases occurs to a different extent earlier in the Plovdiv region than in the Dobrich region, which is completely explainable, because of the later warming in Northern Bulgaria than in Southern Bulgaria. Of primary importance for the development of sunflower is the duration of the interphase periods, which is a consequence of the meteorological conditions of the year and the region and of the genotypic differences between individual sunflower hybrids. The interphase period sowing-germination has a very different duration in the two regions in the first year. The reason for the long germination period in Southern Bulgaria is the low temperatures in March. The remaining interphase periods do not differ significantly between the two regions, nor between the hybrids. In the second year of the study, the interphase periods did not differ significantly, both between the two regions and between the hybrids until the moment of the latter.

: sunflower, phenology, agroecology

agronomy

Presentation: poster