Optimal flowering periods (Manangatang MRU) - Bonnie Flohr (CSIRO)

Optimal flowering periodsBonnie Flohr| Mallee Sustainable Farming updates, Manangatang17 February 2016

AGRICULTURE

Acknowledgements

CSIRO Agriculture• James Hunt, John Kirkegaard, Brad Rheinheimer, Tony Swan

ANU• John Evans

Funding• GRDC and ANU

2 | Optimal flowering periods| Bonnie Flohr

Why optimal flowering periods?

• Autumn rainfall decline (Cai et al. 2012)

• At least partly attributable to anthropogenic climate change (Cai et al. 2013) and results in the systems which bring the ‘autumn break’ to SE Australia being less frequent (Pook et al. 2006, 2009)

• Sowing dates required for current cultivars to achieve optimal flowering periods coincide with marked rainfall decline which has regionally reduced yield

• In addition, > farm size and > extreme spring weather

• Farmers need new cultivar x management strategies to stabilise flowering time


Wheat’s optimal flowering period (OFP)

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• Water stress• Heat stress

• Frost• Disease• Inadequate

growth

OFP

• Critical for yield• A compromise of all factors

• Highest yields come with ~5‐10% frost damage

Optimal flowering periods| Bonnie Flohr

• Previously optimal flowering periods have been defined by last spring frost and first heat event

• Impact of seasonal water supply on optimal flowering period has been overlooked

• Using APSIM to model yield combines historic weather records (including water availability), biomass accumulation and temperature to identify optimal flowering period = novel approach

Things to consider in optimal flowering periods


Method

• Key inputs for model– Year duration (1963‐2013)– MET file for site (SILO)– Soil file for site – Management: TOS (April 1‐ July 15)– Fertiliser– Irrigation– Variety (mid‐fast)


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APSIM sites‐ SE Australian wheat belt


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Optimal flowering period =19 August to 13 September

Optimal flowering periods: Manangatang


Optimal flowering period (95% of achievable yield) +ve standard deviation

(variation)

‐ve standard deviation (variation)

15 day rolling mean

Optimal flowering period

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9 ‐29 September

Lameroo


Waikerie

23‐ 29 August

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OFP is independent of cultivar maturity type

Mid‐ fast spring

Wintervery slow spring


A trade off… drought, frost and heat

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Flowering

date

Yield

(kg/ha)

Mean peak APSIM 9-Aug 2456

Mean peak frost and

heat reduced 25-Aug 1819

Frost and heat index

interception 8-Sep N/A

Waikerie


OFP and declining rainfall: Lameroo

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1998‐2013 vs. 1963‐1997


25 Aug‐ 8 Sept 4 Sept ‐ 19 Sept

• 1. Sowing date

Ways to hit the optimal flowering period

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Reference: NVT, Victorian Winter Crop Summary 2015


APSIM sowing date range for peak average yield (OFP)‐mid‐fast maturity wheat

Location April MayWaikerie > x <Lameroo > x x <

Manangatang > x <

= problematic is large sowing programs

Ways to hit the flowering window

• 2. Genetics x Management

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Early sowing with slow developing cultivars will not be adopted in the majority of the Australian wheat belt (WA, SA, Vic) until there is a winter wheat that is as high yielding as current elite fast developing spring wheat cultivars e.g. Mace, Corack


SA, WA & NW Vic need a fast maturing winter wheat

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Mace

Vrn‐A1 Vrn‐B1 Vrn‐D1

v a v

Krichauff


b v v

Peake


a v v

X Or

Fast winter wheat


v v v

25% of F2 progeny


Fast winter wheat: RAC2341

• RAC2341‐ AGT Roseworthy breeding program– vav x avv

• 70% Mace

• Responds to vernalisation – Requires cold temperature accumulation to initiate flowering, fast‐spring wheats have a low requirement

• Fast to develop once vernalised

• 4 x experimental sites in GRDC early sowing project‐ James Hunt


Flowering time vs. yield ‐ Minnipa

22‐August – 8 September


Minnipa SA results 2015‐ James Hunt

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Yield (t/ha) Time of sowingCultivar 13‐Apr‐15 29‐Apr‐15 13‐May‐15

Wedgetail 2.8 2.5 1.9Eaglehawk 2.9 2.3 1.8RAC2341 3.4 3.6 2.7Cutlass 3.5 3.6 2.9Trojan 3.3 3.9 3.0Mace 2.9 3.8 3.2

Very slow spring 2.2 1.7 0.9Mid winter 2.4 2.0 1.7Fast winter 2.7 2.6 2.0Fast spring 2.0 3.0 2.5P‐value <0.001

LSD (p=0.05) 0.3


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RAC2341 sown 13 April @ Minnipa SA(photo taken 1 Sep 2015‐ James Hunt)

Flowered 26 July2.9 t/ha

Flowered 3 September3.4 t/ha


Temora results 2015

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Grain yield (t/ha) Time of sowing

Cultivar 17‐Apr 27‐Apr 7‐May 15‐May

Wedgetail 4.3 4.1 3.7 3.2

RAC2341 5.5 4.9 4.4 4.3

Gregory 4.7 4.8 3.9 3.8

Condo 4.7 5.8 4.9 4.4

P‐value <0.001

LSD (p=0.05) 0.4


Temora 2015

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RAC2341 (fast winter), a broad sowing window (17 April‐ 15 May) same flowering date


Optimal flowering period

Key points

• Consider spring drought (seasonal water supply) as an important determinate of the optimal flowering period, along side frost and heat

• There is less flexibility in time of sowing with fast maturing wheats to achieve the optimal flowering period than thought, timely sowing cultivars to your environment is key to achieving optimal flowering periods and yield

• Varieties that can respond to the environment (e.g. RAC2341) can hit the optimal flowering period across multiple sowing dates (=flowering date stability), increasing yield and system flexibility in a variable climate


Science

Optimal flowering periods (Manangatang MRU) - Bonnie Flohr (CSIRO)