Contribution of leaves to the yield of sunflowers - Gurley

2015 - 2016

Research organisaton
Funding sources

Trial details

Researcher(s) Loretta Serafin, Mark Hellyer and Peter Perfrement (NSW DPI)
Year(s) 2015 - 2016
Contributor Department of Primary Industries NSW
Trial location(s) Site 3, Gurley, NSW
Further information View external link
Related trials
Contribution of leaves to the yield of sunflowers - Gurley locations

To quantify the contribution of different sunflower leaves to yield and oil quality through applying 12 leaf defoliation treatments.

Key messages
  • Sunflower yields were very low at this site in 2015–16, averaging 0.24 t/ha, and overall variability was very high.
  • The total removal of leaves at the budding stage had the largest impact on plant structures; plant height, head diameter and arc length.
Lead research organisation Department of Primary Industries NSW
Host research organisation N/A
Trial funding source GRDC DAN00197
Trial funding source DPI NSW DAN00197
Related program 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 supplying experiment seed. Technical assistance provided by Delphi Ramsden, Angus Hombsch, Alice Bowler and Bronwyn Brennan (NSW DPI) is gratefully acknowledged. Thanks to Doug Clark, ‘Kyntyre’, Gurley for hosting the experiment.

Other trial partners Doug Clark (co-operator): ‘Kyntyre’, Gurley
Download the trial report to view additional trial information


Crop type Sunflower
Treatment type(s)
  • Crop
Trial type Experimental
Trial design Replicated

Gurley 2015

Sow date 9 September 2015
Harvest date 23 February 2016
Plot size Not specified
Plot replication Not specified

42 kg/ha Granulock Z applied at sowing

Gurley 2016

Sow date Not specified
Harvest date Not specified
Plot size Not specified
Plot replication Not specified
Fertiliser Not specified
Download the trial report to view additional method/treatment information

Download results

Trial results Affect from defoliation treatments on sunflower plant structures

# Treatment 1
Plant height (cm) Head arc length (cm) Head diameter (cm)
1 Control - no leaves removed (0/3) 129.5 13 12.1
2 Budding - remove all leaves (3/3) 66.4 2.5 1.5
3 Budding - remove top 10 leaves (1/3) 123.6 13.6 11.3
4 Budding - remove top 20 leaves (2/3) 113.9 10.5 7.9
5 Budding - remove bottom 10 leaves (1/3) 126.9 11.7 10.2
6 Start of flowering - remove top 10 leaves (1/3) 122.5 12 9.1
7 Start of flowering - remove top 20 leaves (2/3) 126.1 13.5 10.5
8 Start of flowering - remove all leaves (3/3) 121.4 16.1 7.5
9 Start of flowering - remove bottom 10 leaves (1/3) 121 12.5 9.7
10 Flowering complete - remove top 10 leaves (1/3) 126.7 13.2 9.9
11 Flowering complete - remove top 20 leaves (2/3) 121.9 13.2 10
12 Flowering complete - remove all leaves (3/3) 123.8 13.9 9.3

Head arc length cm


Head diameter cm


Plant height cm

Observed trial site soil information
Trial site soil testing
Site Depth Type pH EC P K N A OC CAT
Site 3, Gurley, NSW 0 - 10cm 6.10 16.00 0.49
Site 3, Gurley, NSW 10 - 30cm 7.00 4.00 0.43
Site 3, Gurley, NSW 30 - 60cm 7.80 2.00 0.34
Site 3, Gurley, NSW 60 - 90cm 7.90 0.00 0.28
Site 3, Gurley, NSW 90 - 120cm 8.00 3.00 0.12
Soil conditions
Trial site Soil texture
Site 3, Gurley, NSW Vertisol
Derived trial site soil information
Australian Soil Classification Source
Trial site Soil order
Site 3, Gurley, NSW Vertosol
National soil grid Source
NOTE: National Soil Grid data is aggregated information for background information on the wider area
Actual soil values can vary significantly in a small area and the trial soil tests are the most relevant data where available

Soil properties



Site 3, Gurley NSW 2015

Observed climate information

Rainfall avg ann (mm) 603mm
Rainfall trial gsr (mm) 286mm

Derived climate information

Site 3, Gurley NSW

NOTE: Exact trial site locality unknown - Climate data may not be accurate

Some data on this site is sourced from the Bureau of Meteorology

SILO weather estimates sourced from
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.

Trial report and links

2015 trial report

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Trial last modified: 06-08-2019 07:54am AEST