Matching phenology, environment and variety to optimise wheat yield

Author: | Date: 07 Mar 2018

Take home messages

  • Understanding temperature variance across farms/regions is essential for targeting optimum flowering windows for wheat.
  • Matching varietal maturity to target optimum flowering dates for a given location is key to minimising both frost and heat stress.
  • Generally, no one variety will maximise yield across the full planting window. Yield response for any particular maturity/variety will vary depending on time of sowing.

Introduction

Recommended sowing times for wheat varieties have been developed over many years of NVT testing to predict a optimum flowering window. It is reasonable to assume that if your sowing dates generally line up with your nearest NVT trial sites’ planting dates, then varietal flowering dates and yield response should be similar, all other factors being equal. Varieties selected for the NVT sowing dates are based on maturity length, and as such, not all tested varieties are included in both the main season and early sowing dates.

This however raises a question - if you were to receive planting rain, but your predicted ”optimum” sowing for your wheat variety window doesn’t open for another 2 - 4 weeks, could or should you plant anyway and what effect will this earlier sowing date have on days to flowering? Equally, what effect would this have on your yield potential? Conversely, if you don’t get a season break till very late in your planting window, can you still reasonably expect to get similar yields to the NVT trial data? How significant an effect will heat play during flowering and grain fill?

Background

The DAF research agronomy team has worked with NSW DPI in the Variety Specific Agronomy Package (VSAP) project in 2015 and 2016 looking at the effect of a range of agronomic triggers to optimise yield and grain quality. In 2017, a new project began with a more focused approach, mapping biomass accumulation and growth stage timing for multiple sowing times across the northern grains region. This new project, Optimising Grain Yield Potential in the Northern Grains Region (Winter Cereals) is a GRDC/NSWDPI Bilateral project led by NSWDPI in collaboration with DAF QLD.

In 2015 and 2016, eighteen varieties with a wide range of maturities were selected and planted on three or four sowing dates approximately a month apart from each other. All sowing dates had access to similar starting waters for that particular site, however once emerged the trials were treated as dryland through to maturity.

In 2017 the new project reduced the sowing window gap back from 30 days to 15 days with 30 varieties assessed. Eight trials were planted from Wagga to Emerald, all with the same times of sowing, to compare plant development across eight very different climatic regions.

Results

In 2015, three times of sowing (TOS) occurred with 18 varieties at each site. Sowing dates were spread one month apart to represent early, traditional and late planting windows for the regions the trials were located. For Emerald, dates selected were 15 April, 12 May and 9 June.  For the Goondiwindi site, target sowing dates were 27 April, 26 May & 8 June. The season in 2015 was very dry and daily maximum temperatures started to rise earlier than average at both sites. Tables 1 and 2 show average yield for each variety at each time of sowing and estimated days from planting to 50% anthesis. The season suited quick varieties at both locations, but also showed a significant decline in yield between each time of sowing.

In 2016, there were three times of sowing at Goondiwindi and four at Emerald; Tables 3 & 4 show the results for both trials. Sowing dates for Emerald were 16 March, 13 April, 11 May and 15 June 2016, while Goondiwindi TOS dates were 26 April, 24 May and 4 July.

2016 was a considerably milder and wetter season than 2015 for both sites and average yields reflect this. It must be noted that good in crop rainfall did not fall until the end of May, continuing through to mid-July for that season. This had a noticeable effect on time to anthesis for TOS 1 & 2 at Emerald, which were significantly quicker and more in line with 2015 days to anthesis, while the later TOS 3 and 4 were longer; in particular, TOS 3 did not show the yield drop off when compared to TOS 2 unlike the previous year.

Frost damage was observed, particularly during flowering for TOS 1 at the Goondiwindi site, as would be expected given the planting dates, but only some varieties were affected and none were completely lost as average yields indicate in Table 3. Temperatures did drop down below 2oC at Emerald, no frost damage was observed.

Table 1. Goondiwindi site 2015 -  days to 50% anthesis and grain yield (standardised for moisture) for each of the three planting dates. Letters indicate significant difference (P=0.05) of yield between varieties within a TOS.

 

TOS 1 - 27 April 2015

TOS 2 26th May 2015

TOS 3 8th July 2015

Variety

50% Anthesis (Days)

Grain yield (t/ha)

50% Anthesis (Days)

Grain yield (t/ha)

50% Anthesis (Days)

Grain yield (t/ha)

LongReach Dart

96

4.13

abcde

99

3.87

a

83

2.67

ab

LongReach Spitfire

102

4.18

abcd

105

3.91

a

91

2.41

abc

Sunmate

107

4.33

abc

106

3.86

a

87

2.76

a

Elmore CL Plus

108

4.56

ab

106

3.34

ab

90

1.67

cd

LongReach Crusader

109

4.06

abcde

105

3.43

ab

86

2.07

abcd

Baxter

110

4.13

abcde

108

3.41

ab

89

2.24

abcd

Kennedy

113

3.89

cde

108

3.05

bcd

95

1.74

cd

Suntop

114

4.12

abcde

107

3.42

ab

90

2.58

ab

LongReach Viking

114

4.38

abc

110

2.61

cde

91

2.19

abcd

Sunguard

115

4.03

abcde

109

2.95

bcd

91

1.68

cd

LongReach Gauntlet

116

4.32

abc

108

3.15

bc

93

1.65

cd

Sunvale

117

3.94

bcde

111

3.03

bcd

93

1.92

bcd

EGA Burke

117

4.58

a

110

2.51

de

92

1.64

cd

Mitch

119

4.33

abc

110

3.50

ab

89

2.57

ab

LongReach Lancer

120

4.37

abc

111

2.67

cde

95

1.53

d

EGA Gregory

121

3.54

e

112

2.52

cde

92

2.12

abcd

Strzelecki

124

3.63

de

116

2.23

ef

92

1.96

bcd

EGA Eaglehawk

139

2.48

f

121

1.72

f

96

1.65

cd

Table 2. Emerald site 2015 - Days to 50% anthesis and grain yield (standardised for moisture) for each of the three planting dates. Letters indicate significant difference (P=0.05) of yield between varieties within a TOS.

 

TOS 1 - 15 April 2015)

TOS 2 - 12 May 2015

TOS 3  9 June 2015

Variety

50% Anthesis (Days)

Grain yield (t/ha)

50% Anthesis (Days)

Grain yield (t/ha)

50% Anthesis (Days)

Grain yield (t/ha)

Condo

60.8

4.19

abcd

69

3.90

a

70

2.99

a

Sunmate

61.1

4.15

bcd

70.5

3.86

ab

71

2.94

ab

Baxter

73.9

4.34

abc

79.6

3.52

bcd

78

2.91

abc

Long Reach Spitfire

61.5

4.13

bcd

70.8

3.81

abc

74

2.81

abcd

Mitch

73.4

4.58

a

81.5

3.35

d

81

2.75

abcde

Elmore CL Plus

66.9

4.37

abc

72.5

3.54

bcd

77

2.57

cdef

EGA Burke

72.5

4.40

ab

80.5

3.37

d

82

2.5

bcdef

LongReach Dart

60.5

3.97

d

68

3.47

cd

70

2.91

abc

Suntop

69.8

4.34

abc

75.5

3.48

cd

78

2.52

def

LongReach Crusader

69.9

4.38

abc

76.1

3.32

d

78

2.46

def

LongReach Gauntlet

76.3

4.39

ab

79.5

3.27

d

81

2.45

ef

LongReach Lancer

79.8

4.25

abcd

85.9

3.52

bcd

84

2.28

fg

Sunguard

75.1

4.18

bcd

83.1

3.25

d

81

2.60

bcdef

LongReach Viking

71.5

4.04

cd

78.5

3.30

d

81

2.31

fg

EGA Gregory

78.4

4.12

bcd

87.2

3.21

d

87

2.26

fg

Kennedy

69.3

4.08

bcd

76.6

3.20

d

80

2.27

fg

Strzelecki

91.5

3.58

e

97.4

2.63

e

89

2.32

fg

EGA Eaglehawk

129.6

2.09

f

113.9

2.02

f

96

2.08

g

LSD w/i T (within a time of sowing (TOS) – ie two varieties compared with the same TOS): 361.7
LSD b/w T (between times of sowing – eg a yield in TOS 1 compared with a yield in TOS 3): 590.8

Table 3. Goondiwindi site 2016 - Days to 50% anthesis and grain yield (standardised for moisture) for each of the three planting dates. Letters indicate significant difference (P=0.05) of yield between varieties within a TOS.

 

TOS 1 - 26 April 2016

TOS 2 - 24 May 2016

TOS 3 - 4 July 2016

Variety

50% Anthesis (Days)

Grain Yield (t/ha)

50% Anthesis (Days

Grain Yield (t/ha)

50% Anthesis (Days)

Grain Yield (t/ha)

LongReach Lancer

104.2

5.35

abc

116.8

6.80

a

94.5

4.99

efg

Sunmate

87.2

4.54

fgh

107.0

6.49

ab

82.5

6.03

a

Suntop

98.7

5.18

bcd

109.3

6.54

ab

88.3

5.29

cdef

Elmore CL

99.7

5.28

bc

109.0

5.94

cde

88.8

5.55

abcd

EGA Gregory

104.4

5.63

ab

111.8

6.29

bc

92.5

4.77

gh

Kennedy

95.2

4.48

gh

105.5

6.34

abc

87.5

5.78

abc

Strzelecki

114.7

5.50

abc

115.3

6.34

abc

96.3

4.29

hi

Sunguard

101.7

5.11

cde

110.0

6.22

bc

90.8

4.77

gh

Mitch

106.2

4.41

gh

110.0

6.46

ab

90.8

5.02

efg

LongReach Gauntlet

104.7

4.67

efgh

112.5

6.27

bc

92.3

4.95

fg

LongReach Viking

105.7

5.06

cdef

109.3

5.87

cde

90.5

4.93

fg

LongReach Dart

88.1

4.22

h

105.3

5.69

def

82.0

5.90

ab

LongReach Spitfire

98.7

4.25

gh

106.8

6.05

bcd

86.8

5.46

bcde

LongReach Crusader

100.6

4.31

gh

106.5

5.44

efg

84.3

5.77

abc

EGA Eaglehawk

133.2

5.78

a

125.8

5.51

def

103.8

3.90

i

Baxter

99.4

4.69

defgh

109.5

4.91

h

86.3

5.13

defg

EGA Burke

99.4

4.74

defg

106.5

4.97

gh

89.8

5.02

defg

Wylie

104.9

4.74

defg

110.0

5.24

fgh

89.5

4.63

gh

l.s.d. w/i T: 508
l.s.d. b/w T: 574

Table 4. Emerald site 2016 - Days to 50% anthesis and grain yield (standardised for moisture) for each of the three planting dates. Letters indicate significant difference (P=0.05) of yield between varieties within a TOS.

 

TOS 1 – 16 March 2016

TOS 2 – 13 April 2016

TOS 3 - 11 May 2016

TOS 4 - 15 June 2016

Variety

50% Anthesis (Days)

Grain Yield (t/ha)

50% Anthesis (Days)

Grain Yield (t/ha)

50% Anthesis (Days)

Grain Yield (t/ha)

50% Anthesis (Days)

Grain Yield (t/ha)

Mitch

61.75

4.73

ab

62.75

6.95

a

83.75

4.98

cde

89.75

1.79

gh

LongReach Lancer

74.00

3.72

cd

78.00

5.88

b

89.00

5.32

bc

94.00

2.40

bcdef

EGA Gregory

69.50

3.78

cd

84.74

5.73

bcd

90.00

4.95

cde

91.50

2.79

ab

Kennedy

68.00

2.53

fg

62.75

5.86

bc

76.00

5.91

a

85.27

2.82

a

Suntop

51.00

2.97

e

55.00

5.37

defg

72.25

5.90

a

85.00

2.74

abc

Sunguard

62.75

4.09

c

67.25

5.26

efg

83.75

5.12

cd

88.00

2.27

def

Strzelecki

90.75

4.99

a

99.00

5.47

def

104.00

4.26

f

98.25

1.82

gh

Condo

61.00

2.72

ef

55.00

5.03

ghi

73.50

5.95

a

79.00

2.51

abcd

EGA Burke

61.50

2.31

g

62.75

5.56

bcde

81.75

5.67

ab

89.00

2.67

abc

Elmore CL

62.50

2.76

ef

60.00

5.06

gh

76.00

5.63

ab

84.50

2.69

abc

Baxter

63.50

3.72

cd

64.50

5.49

cdef

81.00

4.74

de

88.00

1.87

gh

LongReach Crusader

62.00

3.00

e

56.75

5.08

fgh

76.00

5.21

c

83.50

2.38

cdef

LongReach Gauntlet

61.00

3.58

d

67.00

5.55

bcde

83.75

4.69

e

88.75

1.65

h

LongReach Viking

58.00

2.55

fg

62.00

5.20

efg

83.75

5.63

ab

90.50

2.03

fgh

Sunmate

55.75

1.46

h

55.00

4.59

j

72.25

5.70

ab

81.03

2.73

abc

LongReach Spitfire

68.00

1.62

h

57.33

4.66

ij

76.00

5.34

bc

79.15

2.48

abcde

EGA Eaglehawk

131.25

4.59

b

130.00

4.73

hij

115.50

3.34

g

107.00

1.04

i

LongReach Dart

65.50

1.67

h

55.00

4.31

j

72.25

4.79

de

79.00

2.09

efg

l.s.d. w/i T: 394
l.s.d. b/w T: 411

Table 5. Emerald site 2017 - Days to 50% anthesis and grain yield (standardised for moisture) for each of the three planting dates. Letters indicate significant difference (P=0.05) of yield between varieties within a TOS.

 

TOS 1 - 20 April 2017

TOS 2 - 5 May 2017

TOS 3  17 May 2017

Variety

50% Anthesis (Days)

Grain Yield (t/ha)

50% Anthesis (Days)

Grain Yield (t/ha)

50% Anthesis (Days)

Grain Yield (t/ha)

Corack

86

4.11

b

78

4.32

a

75

4.12

a

Mitch

88

4.83

a

85

4.09

ab

82

3.56

defg

LongReach Mustang

73

3.85

bcdefg

72

4.33

a

71

3.98

abc

Suntop

82

4.02

bc

80

4.00

abc

79

3.99

abc

Mace

83

4.13

b

79

3.94

abcde

76

3.88

abcd

Beckom

84

3.83

bcdefg

82

4.07

abc

79

3.88

abcd

Scepter

83

4.01

bcd

80

3.73

cdef

80

4.01

ab

Janz

86

3.96

bcde

80

3.86

bcde

80

3.87

abcd

Condo

79

3.74

cdefgh

76

3.93

bcd

74

3.84

abcd

LongReach Spitfire

93

3.90

bcdef

79

3.72

cdef

86

3.69

bcde

LongReach Reliant

95

3.64

efgh

92

3.85

bcde

86

3.70

bcde

TenFour

77

3.46

h

74

3.99

abc

71

3.69

bcde

LongReach Lancer

91

3.90

bcdef

92

3.56

efg

85

3.64

cdef

Sunvale

88

3.72

cdefgh

90

3.80

bcdef

84

3.44

efgh

Kiora

92

3.66

cdefgh

89

3.61

defg

85

3.39

efgh

Coolah

96

3.93

bcdef

93

3.48

fgh

90

3.23

gh

LongReach Dart

78

3.61

efgh

75

3.54

efg

72

3.43

efgh

Cutlass

94

3.77

bcdefgh

95

3.61

defg

92

3.09

h

EGA Gregory

97

3.66

defgh

93

3.48

fgh

89

3.30

fgh

Suntime

94

3.57

fgh

91

3.45

fgh

87

3.22

gh

LongReach Trojan

91

3.50

gh

88

3.36

gh

84

3.33

fgh

DS Pascal

94

3.80

bcdefgh

91

3.17

h

86

3.19

h

Sunmax

113

2.94

i

107

2.42

i

102

2.17

i

EGA Eaglehawk

118

2.84

i

112

2.31

i

109

2.22

i

LongReach Kittyhawk

129

1.12

j

124

0.36

j

114

0.78

j

Sunlamb

144

0.49

k

129

0.59

j

116

0.92

j

EGA Wedgetail

n/a

0.00

 

n/a

0.00

 

n/a

0.00

 

Manning

n/a

0.00

 

n/a

0.00

 

n/a

0.00

 

RAC2341

n/a

0.00

 

n/a

0.00

 

n/a

0.00

 

RGT Accroc

n/a

0.00

 

n/a

0.00

 

n/a

0.00

 

l.s.d. w/i T: 366
l.s.d. b/w T: 355

The 2017 data in Table 5 doesn’t show a significant difference in yield unlike previous years and trials. As a site average, there was no significant difference in yield between TOS dates, however individual varieties like Mitch, Coolah, Cutlass, Sunmax and EGA Eaglehawk all show statistically significant declines in yield between TOS 1 and TOS 3. Most of these varieties are considered longer season varieties for the central Queensland (CQ) environment and highlight the difference a later planting date can make. Interestingly, none of the recognised quick varieties managed to yield significantly better in the later TOS 2 and 3, than the earlier planted TOS 1. This is despite the perception of being better suited sowing at a later date (mainly due to frost management concerns).

Analysis

The general trend across all locations has consistently been declining yield from the first TOS to the last. Excluding an exceptionally early (March) plant, generally the earlier the crop is planted within an accepted planting window, the higher the yield potential (baring frost damage). While frost is front of mind currently as a result of the exceptional frosts seen in 2017, heat stress must also be considered just as significant a threat to growers bottom line. When the data from Tables 1 to 5 is plotted against heat and cold risk charts generated with the CliMate application (climateapp.net.au) a TOS which target safer flowering periods can be identified.

Figure one is a graph showing yield as dot points depending on timing of sowing plotted against heat and frost risk for Goondiwindi in 2015

Figure 1. Goondiwindi – 2015 Probability of heat and cold stress x flowering dates and achieved yield

Heat stress = >30oC Cold Stress = <2oC Risk - 1 in 10 Planting dates - 27th April, 26th May and 8th July 2015 (climateapp.net.au)

CliMate is a free application, which allows you to assess the likelihood of a predefined heat or cold stress event based on historical weather data for a given location. The weather database is extensive, so it is not too difficult to find regionally relevant data for your conditions. Winter cereals flowering in a temperature range lower than 30oC and above 2oC is generally considered as non-limiting to yield potential. When you overlay the flowering dates and yield achieved over the top of this chart, you can very quickly start to understand what factors may have contributed to yield decline during your flowering period.

Figure 1 shows the yield and flowering data from Goondiwindi in 2015 overlayed onto one of these graphs. The green bars show what period of year, (given a risk level of 1 in 10 years of exceeding the min or max temps) you could expect the preferred conditions described above. For Goondiwindi, it indicates that ideally flowering/grain fill should start from the last week of August to avoid an elevated frost, and conclude no later than the third week in September to avoid significant heat stress during flowering and grain fill. Figure 1 also shows that flowering dates for TOS 3 and even longer season varieties in TOS 2 were well into the elevated risk period for heat stress. TOS 1 in that particular year managed to avoid frost damage, hence why yields were so good despite flowering in an elevated frost risk period.

Figure 2 is the same as figure 1 but for the 2016 season, showing that time of sowing two was the best choice as time of sowing one was affected by frost and time of sowing three was affected by heat.

Figure 2. Goondiwindi – 2016 Probability of Heat and Cold Stress x Flowering Dates and Achieved Yield

Heat stress = >30oC Cold Stress = <2oC Risk - 1 in 10 Planting dates - 26th April, 24th May and 4th July 2015 (climateapp.net.au)

The 2016 season saw significantly higher yields but possibly a more traditional response to heat and cold stress. TOS 1 flowering dates were again within the elevated frost risk period, however this time frost did occur and yields suffered as a result. Again TOS 3 yields declined rapidly as the heat stress risk increased. Optimum yields for the site were achieved within the optimum flowering window.

For the Emerald site, significant differences in climate are revealed, as the dynamics of the graph change considerably. The risk of temps below 2oC fall away to a level which it is not considered a likelihood with a 1 in 10 year risk profile. But the low heat stress period is a month shorter than that observed at Goondiwindi.

As with Goondiwindi, 2015 was a hot dry year and as expected, the earlier TOS performed as well as could be expected for the season. It is interesting to again observe that mid-season varieties performed the best for TOS 1. Quicker varieties yielded greater on average in TOS 1 compared to the 2nd and 3rd TOS. For TOS 2 and TOS 3 the quicks out yielded mid and longer season varieties.

2016 was a much milder season, but the site experienced prolonged hot conditions until the late May rain arrived. Thus TOS 1 in March struggled with temperatures in excess of 40°C during emergence and 30°C at flowering and grainfill. Comparatively, longer season TOS 2 varieties and all TOS 3 had mild, almost ideal flowering and grain fill conditions, hence the significant yield response difference from the 2015 TOS 3 date. Rain stopped in mid-July, so conditions returned back to a drier CQ winter/spring as can be seen by the significant yield drop for TOS 4 trying to flower as conditions quickly rose past the 30oC heat stress threshold.

Figure three shows the same graph of yield over heat and frost risk as the previous two graphs, however for Emerald in central Queensland. As Emerald has very low frost risk most times of sowing were in the low risk area.

Figure 3. Emerald Research Facility 2015 & 2016 - Probability of Heat and Cold Stress x Flowering Dates and Yield

Heat stress = >30oC Cold Stress = <2oC Risk - 1 in 10

In spite of the nearly four month “optimum” for flowering and grain fill at this CQ site, the trend in yield x flowering response over the past three years now indicates that this window may not be as wide as it seems. To date, highest yields, have been achieved flowering between the 2nd and 4th weeks of June, which is exceptionally early, even for many in CQ. However, if the frost risk was understood and deemed acceptable, for a given region/client, then you would ideally be targeting a flowering date in that range.

Conclusion

Targeting an optimum flowering date is critical to maximise grain yield by balancing heat and frost risks. Selecting varieties with known and understood flowering dates, allows growers and agronomist to make more informed variety/maturity selections for future crops. As this data shows, days to flowering can vary significantly between locations and between planting dates, so observing and recording on-farm flowering dates from year to year could become a very useful management tool for your particular location in trying to optimise varietal selection.

Frost risk is a significant consideration, as 2017 showed us once again, however so too is heat stress. Growers and agronomist must be cautious not to take too conservative approach to frost mitigation, as chances are it will cost you significantly in yield also as a result of heat stress. Those considering planting very late in the traditional planting window with a high risk of flowing in heat stress conditions may actually be better off waiting a month or so and chasing a potentially more lucrative early summer crop instead.

Acknowledgements

The research undertaken as part of this project is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC. The author would like to thank them for their continued support. We would also like to acknowledge and thank collaborators and co-operators over the past three years, who have allowed us to conduct on-farm trials across QLD. And to recognise the DAF Research Agronomy teams located in Emerald, Toowoomba and Goondiwindi for all the work that went into managing the trial programs over the past three years.

Contact details

Darren Aisthorpe
Department of Agriculture and Fisheries QLD
99 Hospital Rd. Emerald QLD 4720
Ph: 07 4991 0808
Mob: 0427 015 600
Email: Darren.aisthorpe@daf.qld.gov.au

Varieties displaying this symbol beside them are protected under the Plant Breeders Rights Act 1994.

GRDC Project code: DAN00167