Determining Optimum Seeding Rates for Diverse Hard Red Spring Wheat Varieties –
Research from ND/MN, USA
Grant Mehring
Ph.D Candidate and Research Specialist, North Dakota State University
Co-advisors: Dr. Joel K. Ransom, North Dakota State University
Dr. Jochum J. Wiersma, University of Minnesota
Background Seeding rate of HRSW in the field is a critical
management decision
What are factors that affect plant stand?
• Seedbed preparation
• Soil moisture
• Seeding depth
• Crop rotation
• Seed quality
• Herbicide carryover
• Planting date
• Weeds
• Insects
• Disease
Seeding rate
Calculating Seeding Rate
• Several methods exist
1. Broadcast and incorporate
2. Bushels per acre
3. Kernel weight and germination
4. Kernel weight, germination + seedling mortality
Broadcast and incorporate
Bushels Per Acre Seeding Rate
• Common method in North Dakota, Minnesota, and Manitoba
• Manitoba: 1-2.6 bushels per acre • To get population of 1.0-1.2 million plants per acre
• Source: Spring Wheat Production and Management Manitoba
• North Dakota: 1-2 bushels per acre
• This method may or may not take into account germination and seeds per pound
Let’s look at the math
Albany Linkert Faller
-grams/500 kernels-
Seeding Rate 15.1 17.3 19.8
-----bu/ac---- ----million seeds/ac----
1 0.9 0.8 0.7
1.25 1.1 1.0 0.9
1.5 1.4 1.2 1.0
1.75 1.6 1.4 1.2
2 1.8 1.6 1.4
Germination and kernel weight
• Seeding rate may be way off with bushels/acre
• Better to consider: • Germination (%) – spring wheat typically high but
can vary (certified seed vs. bin-run)
• Kernel weight – seeds/kg or 1000 kernel weight
Albany Linkert Faller
-grams/500 kernels-
Seeding Rate 15.1 17.3 19.8
--million seeds/ac-- ----million seeds/ac----
1 1 1 1
1.25 1.25 1.25 1.25
1.5 1.5 1.5 1.5
1.75 1.75 1.75 1.75
2 2 2 2
If we used germination and kernel weight
Environment is the wild card…
Environment is the wild card… Seeding Rate Prosper, ND, 2013 Kimball, MN, 2015
Seeds/Acre Actual Stand % Stand Loss Actual Stand % Stand Loss
600,000 647,869 +8% 577,977 -4%
1,000,000 1,012,942 +1% 855,470 -15%
1,400,000 1,299,193 -8% 1,140,627 -19%
1,800,000 1,607,571 -11% 1,303,977 -28%
2,200,000 1,918,713 -13% 1,576,799 -29%
23 Environments from 2013-2015
• Very diverse environments
• Overall, use seedling mortality for most accurate seeding rate
Seeding Rate 23 environments
Seeds/Acre Actual Stand % Stand Loss
600,000 580,977 -3%
1,000,000 900,872 -10%
1,400,000 1,195,551 -15%
1,800,000 1,452,775 -19%
2,200,000 1,735,333 -21%
Use seedling mortality!
• Seedling mortality – 10-20% expected stand loss even under good seedbed
• Depends on environmental conditions
• Depends on seeding rate
• More stand loss as seeding rate increases
Scout for plant stand
• When? Before tillering (Zadoks 21, Feekes 2, Haun 2)
• How? Count plants in a known length of row and row spacing. Throw out a quadrat. Work the simple math
• Alternative tools - Sensor technology.
• An easy one is a cell phone app called Canopeo™ • Measures green area compared to soil
High Seeding Rate
Mid Seeding Rate
Low Seeding Rate
Justification of my research
• Seeding rate of HRSW in the field is a critical management decision • Impacts yield and management
• Previous research has concluded that seeding rate for maximum yield varies among cultivars
• Classical seeding rate X cultivar experiment is inefficient to keep up with new HRSW releases
Objectives of my research 1. Understand unique cultivars varying ability to tiller
2. Determine yield responses of diverse cultivars to seeding rate at different planting dates
3. Understand how seeding rate curves change over longitudes
4. Develop predictive tools that select seeding rates based on presence of three qualitative traits, semi-dwarf plant stature (Rht-B1, Rht-D1) and photoperiod sensitivity (Ppd-D1) within a cultivar and known planting dates in the field
Simplified • You want to plant your wheat variety at the correct
seeding rate
• Without just guessing or always planting the same rate
Seeding rate effect on stems/plant • Classical response
• Less tillers as seeding rate increased
• Almost never uniculm, but can happen
Seeding Rate 23 env Low env High env
Seeds/Acre Stems/Plant
600,000 4.0 2.4 6.5 1,000,000 2.8 1.8 4.6 1,400,000 2.2 1.3 3.5 1,800,000 1.9 1.1 2.8 2,200,000 1.6 1.0 2.4
Planting date effect on stems/plant • Less tillers when planting is delayed
• Increase seeding rate when planting is delayed
Seeding Rate Optimum Planting 5 weeks later
Seeds/Acre Stems/Plant
600,000 4.3 3.7 1,000,000 3.2 2.6 1,400,000 2.6 2.0 1,800,000 2.3 1.8 2,200,000 2.1 1.5
Lodging
Lodging
• An environmentally dependent characteristic
• Not desirable as it lowers yield and slows combining
• In ND/MN, we have some high yield potential cultivars which lodge
• We have some taller cultivars that lodge
• We have some years (2015) where everything lodges several times.
• There are management practices to decrease lodging
Seeding rate effect on lodging • Classical response
• More lodging as seeding rate increased
• Lodging dependent on environment
Seeding Rate 23 env Low env High env
Seeds/Acre -----1 (low) – 9 (high)-----
600,000 1.6 1.1 3.8 1,000,000 1.8 1.1 4.6 1,400,000 2.1 1.1 5.4 1,800,000 2.3 1.3 5.7 2,200,000 2.4 1.3 5.7
Hill Plot Experiment
• Crookston, MN and Prosper, ND
• 12 cultivars planted in single seed hill plots
• 4-5 planting dates
• Objectives: 1. Tillering differences
among cultivars
2. Tillering differences at planting dates spaced by 1 week intervals
Stems per plant in hill plots averaged over four planting dates, Prosper, ND, 2014.
• 19 to 44 stems/plant range
• Large cultivar differences in propensity to tiller
Cultivar Stems/Plant Sabin 43.9
Marshall 36.1
Albany 36.0
Knudson 33.9
Faller 31.7
Oklee 28.4
Kuntz 26.7
Vantage 25.8
Rollag 25.0
Briggs 24.2
Kelby 20.4
Samson 18.7
LSD (0.5) 6.2
Table 2. Stems per plant of HRSW cultivars in hill plots and conventional plantings, Prosper, ND, 2014.
• Ranks from hill plots not the same as conventional seeding rates
Cultivar Hill Plots PD 1 PD 2 ------stems/plant------
Sabin 43.9 2.3 2.6
Marshall 36.1 2.9 4.2
Albany 36.0 2.7 4.2
Knudson 33.9 2.7 3.2
Faller 31.7 2.5 2.7
Oklee 28.4 2.2 2.5
Kuntz 26.7 2.4 3.8
Vantage 25.8 2.5 2.7
Rollag 25.0 2.6 4.0
Briggs 24.2 2.9 3.6
Kelby 20.4 2.4 3.0
Samson 18.7 2.0 3.1
LSD (0.5) 6.2 0.7 0.7
Cultivar Hill Plots PD 1 PD 2 ------stems/plant------
Sabin 1 10 11
Marshall 2 1 1
Albany 3 3 1
Knudson 4 3 6
Faller 5 6 9
Oklee 6 11 12
Kuntz 7 8 4
Vantage 8 6 9
Rollag 9 5 3
Briggs 10 1 5
Kelby 11 8 8
Samson 12 12 7
LSD (0.5) 6.2 0.7 0.7
Methodology, Seeding Rate Factors:
• Planting Date – Early and Late
• Varieties – 12
• Seeding Rate – 0.6, 1.0, 1.4, 1.8, 2.2 million seeds/acre
• Prosper, ND, Crookston and Lamberton, MN
• Chosen to represent a wide latitudinal spread
ND MN
Methodology, Seeding Rate
Factors:
• Varieties – 12
• Seeding Rate – 0.6, 1.0, 1.4, 1.8, 2.2 million seeds/acre
• Kimball, Perley, and Hallock, MN
• Chosen to validate the planting date study in a similar latitude/geography
ND MN
Methodology, Seeding Rate
• Data collected: plant stand, head counts, yield
Tillers impact spikes per acre
Heading counts at 23 environments
Feekes 1 Feekes 11 Feekes 11 Yield
million seeds/ac stems/ plant million stems/ac bu/ ac
0.6 4.0 2.1 76.6 9.0 2.8 2.4 79.6 1.2 2.2 2.5 80.2 1.5 1.9 2.5 80.0 1.7 1.6 2.6 79.7
The big question – Do diverse HRSW cultivars need different seeding rates? • The short answer is yes, but it depends on the
weather during a growing season
• Every environment is different
• These varieties are not the same as yours, but much of the underlying principles can apply
Group Variety Day length Sensitivity
Rht1 Rht2
1 Albany + + -
Faller + + -
2 Knudson - + -
Samson - + -
3 Briggs + - -
Vantage + - -
4 Sabin - - -
Oklee - - -
5 Kelby - - +
Kuntz - - +
6 Marshall + - +
Rollag + - +
Table 7.HRSW cultivars and group characteristics
Seeding Rate (million seeds/acre)
Variety 6.0 1.0 1.4 1.8 2.2
-----------------bu/ac--------------
Albany 82.9 86.9 86.2 84.4 81.2
Briggs 75.8 78.8 78.6 77.5 76.2
Faller 82.6 84.7 85.6 84.3 84.6
Kelby 74.8 78.5 79.3 79.3 79.8
Knudson 79.1 81.7 82.2 81.8 81.9
Kuntz 71.5 74.8 75.2 75.5 76.6
Marshall 72.6 73.8 75.4 75.2 75.5
Oklee 76.1 79.4 79.2 79.2 77.6
Rollag 73.9 78.2 79.9 81.0 82.1
Sabin 80.7 80.0 79.2 79.1 77.7
Samson 79.7 85.0 86.6 87.1 86.7
Vantage 71.0 74.0 75.2 76.2 76.2
Seeding Rate effect on yield at 23 environments, 2013-2015
Let’s simplify the trends
• These three yield trends are represented in that mess of data points from the previous table
Seeds/acre Seeds/acre Seeds/acre
Yield Yield Yield
Albany
• Very high yield potential
• Semi-dwarf, photoperiod sensitive
• Top tillering variety in my study
• Plant on the low end of optimum
Seeding Rate (million seeds/acre)
Variety 6.0 1.0 1.4 1.8 2.2
-----------------bu/ac--------------
Albany 82.9 86.9 86.2 84.4 81.2
Briggs
• Not a semi-dwarf, very tall
• Most prone to lodging
• Do not plant too dense
• Optimum seeding rate in middle
Seeding Rate (million seeds/acre)
Variety 6.0 1.0 1.4 1.8 2.2
-----------------bu/ac--------------
Faller 82.6 84.7 85.6 84.3 84.6
Faller
• Highest yield potential in study
• Semi-dwarf, though still tall
• Tillers in the mid range
• Optimum or slightly below is best
Seeding Rate (million seeds/acre)
Variety 6.0 1.0 1.4 1.8 2.2
-----------------bu/ac--------------
Albany 82.9 86.9 86.2 84.4 81.2
Kelby
• Semi-dwarf, photoperiod sensitive
• 5 bushel increase from lowest to mid
• Plant at the mid range
Seeding Rate (million seeds/acre)
Variety 6.0 1.0 1.4 1.8 2.2
-----------------bu/ac--------------
Kelby 74.8 78.5 79.3 79.3 79.8
Knudson
• Semi-dwarf, photoperiod insensitive
• Very little increase in yield at any SR
• Plant lower than recommended
Seeding Rate (million seeds/acre)
Variety 6.0 1.0 1.4 1.8 2.2
-----------------bu/ac--------------
Knudson 79.1 81.7 82.2 81.8 81.9
Kuntz
• Semi-dwarf, photoperiod insensitive
• Plant at recommended or just below
Seeding Rate (million seeds/acre)
Variety 6.0 1.0 1.4 1.8 2.2
-----------------bu/ac--------------
Kuntz 71.5 74.8 75.2 75.5 76.6
Marshall
• Very old variety
• Semi-dwarf, photoperiod sensitive
• Plant at recommended rate
Seeding Rate (million seeds/acre)
Variety 6.0 1.0 1.4 1.8 2.2
-----------------bu/ac--------------
Marshall 72.6 73.8 75.4 75.2 75.5
Oklee
• Not a semi-dwarf, photoperiod insensitive
• No yield increase above the second seeding rate
• Plant below recommended
Seeding Rate (million seeds/acre)
Variety 6.0 1.0 1.4 1.8 2.2
-----------------bu/ac--------------
Oklee 76.1 79.4 79.2 79.2 77.6
Rollag
• Short variety, photoperiod sensitive
• Mid range tillering capacity
• Yield doesn’t flatten out at highest SR
• Plant at recommended or above depending on seed costs
Seeding Rate (million seeds/acre)
Variety 6.0 1.0 1.4 1.8 2.2
-----------------bu/ac--------------
Rollag 73.9 78.2 79.9 81.0 82.1
Sabin
• Tall variety, photoperiod insensitive
• Prone to lodging
• Yield decreases as SR increases
• Plant below recommended
Seeding Rate (million seeds/acre)
Variety 6.0 1.0 1.4 1.8 2.2
-----------------bu/ac--------------
Sabin 80.7 80.0 79.2 79.1 77.7
Samson
• High yield potential
• Semi-dwarf, photoperiod insensitive
• 7 bushel increase
• Plant at recommended or just above
Seeding Rate (million seeds/acre)
Variety 6.0 1.0 1.4 1.8 2.2
-----------------bu/ac--------------
Samson 79.7 85.0 86.6 87.1 86.7
Vantage
• Tall variety, photoperiod sensitive
• Very, very strong straw, will not lodge
• Plant at recommended SR
Seeding Rate (million seeds/acre)
Variety 6.0 1.0 1.4 1.8 2.2
-----------------bu/ac--------------
Vantage 71.0 74.0 75.2 76.2 76.2
Yield Conclusions
• Varieties are different
• Some can be planted below recommended and yield at optimum
• Some need higher SR
• Some tiller so well the lowest seeding rate yields top
• Take home – do not go out and cut seeding rates in half
• Use knowledge of cultivars height, lodging, tillering, and planting date to adjust slightly up or down
Seeding Rate
Seeding Rate
Seed cost1 Yield
Gross Income2
Net Income
Seeds/ac -Bushels/ac- $/acre
Bushels/ac $/ac $/ac
600,000 0.9 10.80 82.2 415.10 404.31
1,000,000 1.5 18.00 90.1 454.90 436.90
1,400,000 2.1 25.20 92.3 466.00 440.80
1,800,000 2.6 31.20 91.8 463.44 432.24
2,200,000 3.2 38.40 82.2 414.93 376.53
Table 7. Costs and benefits associated with seeding rate with yields from Kimball, MN, 2015. 1 Seed cost of $12.00 per bushel of HRSW. 2 December wheat price of $5.05.
Conclusions
• Environment is major factor in tiller production and yield
• HRSW varieties do differ in seeding rates for optimal yield
• Economic analysis shows 1.4 million as optimum
• Consider lodging, height and yield potential of individual cultivars on your farm
• Consider planting date
Questions
