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Loretta Serafin, Mark Hellyer and James Filby (NSW DPI)
|Contributor||Department of Primary Industries NSW|
Willow Tree, NSW
|Further information||View external link|
To quantify the contribution of different sunflower leaves to yield and oil quality by applying 12 leaf defoliation treatments.
Sunflowers are generally considered a minor crop in the northern grains region. However, they play an important role in providing a broadleaf summer crop rotation option. An individual sunflower plant produces on average 2000–6,000 cm2 of leaf area, which drives yield and oil content.
Identifying which leaves contribute most towards yield and oil content helps inform decisions around 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 through maintaining green leaf area.
|Lead research organisation||
Department of Primary Industries NSW
|Host research organisation||N/A|
|Trial funding source||GRDC DAN00197|
|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 supplying seed for the experiment. Technical assistance provided by Delphi Ramsden, Alice Bowler, Max Cloake and Jim Perfrement (NSW DPI) is gratefully acknowledged. Thanks to Joe Fleming, ‘Parraweena’, Willow Tree for hosting the experiment. Thanks to Neroli Graham for assistance with the statistical analysis.
|Other trial partners||Joe Fleming, ‘Parraweena’, Willow Tree|
|Crop type||Oilseed: Sunflower|
|Sow rate or Target density||Not specified|
|Sowing machinery||Not specified|
|Sow date||9 October 2016|
|Harvest date||24 February 2017|
|Plot size||Not specified|
|Plot replication||Not specified|
|Plot blocking||Not specified|
|Plot randomisation||Not specified|
|Paddock history||Not specified|
|Soil amelioration||Not specified|
|Seed treatment||Not specified|
|Other trial notes||
Crop type: Sunflower (Hybrid: Ausigold 62)
Starting soil water and rainfall:
The site was soil cored before sowing and found to have 130 mm of plant available water (PAW) to a depth of 1.2 m. Rainfall was recorded at the experiment site
The height of five plants in each plot was measured before harvest, taken from ground level up to the point of attachment at the back of the head. The average plant height in the experiment was 141.7 cm. Removing all leaves at the budding stage had the greatest affect on plant height, at only 117.5 cm, a 25% reduction .
Head diameter and arc length
The head diameter and arc length of five plants in each plot were measured before harvest. Head diameter was measured across the back of the head and arc length across the front face of the head. The average head diameter was 15.9 cm across all treatments. Total leaf removal at budding had the largest impact on head diameter, reducing it to 3.6 cm. This was closely followed by removing 2/3 of the leaves at budding and removing all the leaves or 2/3 at the start of flowering
The average arc length was 16.5 cm. There were significant differences between defoliation treatments. Removing all leaves at budding had the largest affect on arc length reducing it to 3.2 cm. Removing all leaves at the start of flowering and removing 2/3 of leaves at budding also significantly reduced the arc length to 10.4 cm and 7.3 cm respectively. There was no effect on arc length from all of the 1/3 leaf removal treatments compared with the control
Harvested grain yield at 9% moisture ranged from 0.12 t/ha to 0.97 t/ha at this site. There was a large and significant effect from defoliation treatments on yield. The largest effects on yield resulted from removing all leaves at all three of the targeted growth stages (budding, start of flowering and flowering completion). Removing the top 2/3 of the leaves at budding resulted in a similar yield reduction as the total leaf removal treatments . Removing the bottom 1/3 of leaves at the start of flowering (R5.1) improved yield compared with the control. Removing the top 1/3 of leaves at budding, start of flowering or flowering completion did not affect yield compared with the control, neither did removing the bottom 1/3 of leaves at budding or removing 2/3 of leaves at the start of flowering or flowering completion
||Plant height (cm)||Head arc length (cm)||Head diameter (cm)|
|1||█ Control - no leaves removed (0/3)||144.7||21.4||19.1|
|2||█ Budding - remove all leaves (3/3)||117.5||3.2||3.6|
|3||█ Budding - remove top 10 leaves (1/3)||146.8||17.6||18.1|
|4||█ Budding - remove top 20 leaves (2/3)||137.6||7.7||9.8|
|5||█ Budding - remove bottom 10 leaves (1/3)||152.5||22.2||19.6|
|6||█ Start of flowering - remove top 10 leaves (1/3)||146.6||19.4||18.1|
|7||█ Start of flowering - remove top 20 leaves (2/3)||132.9||16.9||17.1|
|8||█ Start of flowering - remove all leaves (3/3)||139.4||10.4||11.6|
|9||█ Start of flowering - remove bottom 10 leaves (1/3)||146.3||21.2||19.2|
|10||█ Flowering complete - remove top 10 leaves (1/3)||139.4||19.6||18.1|
|11||█ Flowering complete - remove top 20 leaves (2/3)||157.3||20.6||19.6|
|12||█ Flowering complete - remove all leaves (3/3)||138.9||17.6||17.5|
|LSD||(P=0.05): 13.05||(P=0.05): 4.38||(P=0.05): 2.36|
|Rainfall avg ann (mm)||668.9mm|
|Rainfall trial gsr (mm)||639mm|
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.