Density multiply maturity interactions for grain yield in sunflower

Abstract

Variation in grain yield response to density (10 000, 30000, 50000, 70000, 90 000 and 110 000 plants/ha), of 2 sunflower hybrids differing in maturity (Hysun 11 and Hysun 30), was examined over a range of yield levels provided by 9 locations. While the interaction between hybrid, density and site was statistically highly significant, its value for commercial recommendations was limited. Optimum yields by each hybrid at each yield level did not differ significantly from yields at densities of 50000 plants/ha. When combined with Victorian and southern Queensland data, the responses were consistent over sites, years and times of sowing. This suggests that valid agronomic recommendations over regions may be based on data for 1 region, providing a suitable data set covering the range of yield expectations is obtained. The regression technique, which related grain weight per plant to area per plant, enhanced the sensitivity in data analysis, simplified data presentation, and provided a framework for interpreting differences between hybrids in density response.