Production components of sunflower cultivars at different sowing times

ABSTRACT The sowing time is of fundamental importance for achieving high yields in the sunflower (Helianthus annuus L.) crop, reducing risks and losses and maximizing the crop yield. This study aimed at evaluating the effect of the sowing time on morphological (plant height, number of leaves, stem diameter and head diameter) and production (1,000-achene weight and total yield) traits. The experiment was conducted in the 2017/2018 and 2018/2019 crop seasons, using a randomized blocks design, in a 3 × 2 bi-factorial scheme, with three sowing times (October 20, November 19 and December 22) and two hybrids (BRS 321 and BRS 323). A negative interference from the environment and sowing time was observed for all the analyzed variables. The third sowing time (December 22), in both crop seasons, resulted in a drastic reduction in the morphological and production traits of the cultivars, with a 50 % reduction in the yield of achenes.