Contribution of leaves to the yield of sunflowers – Willow Tree 2016–17

Abstract

Key findings •• Sunflower yields were greatly affected by the various defoliation treatments, ranging from 0.12 t/ha to 0.97 t/ha. •• Reductions in yield, of between 55% and 82% compared with the control resulted from total leaf removal at all three of the targeted growth stages (budding, start of flowering and flowering completion) as well as removing two-thirds of the leaves at budding. •• There was no negative effect on grain yield from removing the bottom third of leaves at budding or the start of flowering. Removing the bottom third of leaves at the start of flowering actually provided a slight yield advantage over the control treatment. The largest effect on plant height, head diameter and head arc length were caused by removing all leaves at the budding stage.