Contribution of leaves to the yield of sunflowers - Pine Ridge
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To quantify the contribution of sunflower leaves to yield and oil quality through the application of twelve leaf defoliation treatments.
Sunflowers are generally considered a minor crop in the NSW northern grains region.
However, they play an important role in providing a broadleaf summer crop rotation option.
An individual sunflower plant produces on average between 2000–6,000 cm2 of leaf area, which drives yield and oil content.
Identifying which leaves contribute most towards yield and oil content helps growers make
decisions about disease, pest and general crop management in sunflower crops. Whether it is
because the crop is infected with a disease such as powdery mildew or has insect damage e.g.
loopers, the end result is a need for growers and advisors to know where and when to spend
money in crop protection to achieve the best economic return on investment of maintaining
green leaf area.
This experiment was one of three sunflower leaf-loss sites conducted in the 2015–16 season, with the other sites being located at Gurley and Willow Tree.
Sunflower grain yield averaged 1.07 t/ha at this site with the highest yields obtained from the control and the treatments where only the bottom one third (1/3) of leaves were removed.
The total leaf removal treatments had the largest effect on yield, at worst yielding only 0.16 t/ha.
Removing all leaves at budding or at the start of the flowering growth stages had the largest effect on plant structures.
Total leaf removal at the end of flowering had the largest effect on 1000 grain weight and test weight.
Lead research organisation
Department of Primary Industries NSW
Host research organisation
Trial funding source
Trial funding source
DPI NSW DAN00197
Tactical agronomy for selected crops in the northern region (safflower, linseed, sunflower)
This experiment was part of the project Tactical agronomy for selected crops in the northern region (safflower, linseed, sunflower) (DAN00197), with joint investment by NSW DPI and GRDC. Thanks to Nuseed and Neil Weier for the supply of experiment seed. Technical assistance provided by Delphi Ramsden (NSW DPI), Angus Hombsch, Alice Bowler and Bronwyn Brennan (formerly NSW DPI) is gratefully acknowledged. Thanks also to Neroli Graham, NSW DPI for assisting with data analysis. Thanks to Peter Winton, ‘Windy Station’, Pine Ridge for hosting the experiment.
Trial results Impact of defoliation treatments on plant structures
Head diameter (cm)
Plant height (cm)
Head arc length (cm)
Control - no leaves removed (0/3)
Budding - remove all leaves (3/3)
Budding - remove top 10 leaves (1/3)
Budding - remove top 20 leaves (2/3)
Budding - remove bottom 10 leaves (1/3)
Start of flowering - remove top 10 leaves (1/3)
Start of flowering - remove top 20 leaves (2/3)
Start of flowering - remove all leaves (3/3)
Start of flowering - remove bottom 10 leaves (1/3)
Flowering complete - remove top 10 leaves (1/3)
Flowering complete - remove top 20 leaves (2/3)
Flowering complete - remove all leaves (3/3)
Head arc length cm
Head diameter cm
Plant height cm
Site 3, Pine Ridge NSW 2015
Observed climate information
Rainfall avg ann (mm)
Rainfall trial gsr (mm)
Derived climate information
Site 3, Pine Ridge NSW
NOTE: Exact trial site locality unknown - Climate data may not be accurate
SILO weather estimates sourced from https://www.longpaddock.qld.gov.au/silo/
Jeffrey, S.J., Carter, J.O., Moodie, K.B. and Beswick, A.R. (2001). Using spatial interpolation to construct a comprehensive archive of Australian climate data , Environmental Modelling and Software, Vol 16/4, pp 309-330. DOI: 10.1016/S1364-8152(01)00008-1.
Loretta Serafin, Mark Hellyer and Peter Perfrement (NSW DPI)
Searching GRDC final reports...
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