Morphophysiological aspects of ornamental sunflowers cultivated in different growing seasons under semi-arid conditions

ABSTRACT Knowledge of how climatic conditions affect plant morphophysiology is essential for understanding to manage the growth cycles different crops. The aim this study was evaluate effects growing seasons in a semi-arid area on morphophysiological variables ornamental sunflower plants. experiment carried out randomized block design split-plot arrangement with four replicates. Six cultivars (‘Bonito de Outono Sortido’, ‘Sol Noturno’, Vermelho’, ‘Jardim Amarelo Alto’, ‘Girassol F1 Sunbright Supreme’ and Vincents Choice’) were evaluated main plots two (GS) subplots (GS1 - warm climate GS2 mild climate). Evaluations gas exchange, chlorophyll indices, leaf surface at reproductive stage (R5.5). cultivation sunflowers regions significantly affected by season. Changes exchange plants reflected high phenotypic plasticity characteristic species. under season, when air temperature solar radiation are high, could be limited due elevated transpiration rates. Therefore, it recommended that they grown mainly during moderate season regions.