Dryland safflower response to plant population in northern NSW – 2015

Abstract

Key findings •Low temperatures immediately after sowing did not inhibit crop germination or establishment. •Increasing plant population resulted in significant increases in overall plant height and the height of the lowest flower. •In the late May sown safflower, canopy closure and maximum normalised difference vegetation index (NDVI) levels occurred in all populations 25 days before the start of flowering. In comparison, the crop canopy of the July sown safflower was smaller and less developed. Maximum NDVI was delayed in the lowest populations – just 13 days before flowering compared with higher populations reaching a maximum 27 days before flowering. •Plant population had no effect on leaf area index and sunlight interception at flowering. •Crop canopy leaf area (at flowering) of the late May sown crop was almost double the leaf area of the July sown crop. •Average crop canopy light interception was 36% higher in the late May sown crop compared with the July sown crop. •Delaying sowing decreased the overall length of the crop cycle. •Increasing plant population increased overall plant height and the height above ground of the lowest flower. •Higher plant populations were the first to start flowering. •In the late May sown safflower, yields plateaued at populations greater than 30 plants/m2. Yield was 20% lower at 17 plants/m2 population. Seed size was maximised at lower populations. •In the July sown safflower, there was no yield or seed size response to plant population