Growth of ornamental sunflowers in two growing seasons under semiarid conditions

Sunflower is considered a temperate zone crop but it can perform well under varying climate conditions. In this context, the aim of this study was to evaluate the growth of ornamental sunflower cultivars for cutting in two growing seasons in semiarid conditions. Sunflowers cultivars were sown in a randomized complete design in a split plot system, with four blocks. Six cultivars were evaluated (‘Bonito de outono sortido’, ‘Sol noturno’, ‘Sol vermelho’, ‘Jardim amarelo alto’, ‘Sunflower F1 sunbright supreme’ and ‘Sunflower F1 vincents choice’) in the main plots and two growing seasons in the subplots (GS1 – hot weather and GS2 – mild weather). Plant emergence percentage, plant height, stem diameter, number of leaves and internal inflorescence diameter were significant affected both by sunflowers cultivars and growing seasons.  Emergence speed index and external inflorescence diameter were significantly affected by the interaction of cultivars and growing seasons. The obtained results indicated ‘Sol vermelho’ for cultivation in growing seasons with mild temperatures (GS2) and 'Sunflower F1 vincents choice' recommended for both growing seasons with mild climatic (GS2) and in warmer conditions (GS1). Although all other cultivars studied have not been indicated immediately, they may be considered for cultivation, but more studies are necessary for better acclimatization.