Seed set in sunflower crops on the central Darling Downs, Queensland

Abstract

In generally fine weather in 1974-75, seed set in heads open to pollination (79-97%) was positively correlated with seed set in bagged heads at the same site (0-48%). Seed set in the open heads was not significantly correlated with percentage commercially usable achenes (40-84%). Seed set in open heads was independent of number of beehives within 3 km and area of crop, indicating that pollinators were adequate. In 1975-6, heads which flowered during 5 wet days had lower seed set than heads which flowered in fine weather. Achene yield/head was also lower. This is attributed to reduced honeybee activity during the wet weather and low self-compatibility in the cv. studied.