A. Mangin1*, Y. Lawley1, A. Brûlé-Babel1, D. Flaten2 and J.J. Wiersma3

1Dept. Plant Science, University of Manitoba 2Dept. Soil Science, University of Manitoba; 3Dept. Agronomy and Plant Genetics, University of Minnesota *(Ummangia@MyUmanitba.ca)

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AAC Brandon AAC Cameron Prosper

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Agronomic Management to Reduce Lodging Risk for Spring Wheat in Western Canada

High nitrogen (N) requirements of milling quality high-yielding spring wheat varieties has increased concerns about lodging. Lodging is the displacement of plant stems from vertical position due to unfavorable canopy structure paired with adverse weather conditions. Agronomic management through varietal selection, N fertilizer management (sources, rates, timing), seeding rate/plant density, and plant growth regulators (PGR) applications alter crop canopy structure and development. Therefore, management strategies may be used to optimize plant development and canopy structure while increasing lodging resistance and resource partitioning to the developing grain.

Objective Determine how agronomic management through, varietal selection, N management, plant density and PGR application, alters crop canopy structure development, and resulting lodging and grain yield and quality

Introduction

Methods

A 2-year small-plot field research project, was initiated at two locations in Manitoba during the 2018 growing season. Two field experiments (Exp. 1 and 2) were used to determine the effect of a number of agronomic strategies to minimize lodging risk while maximizing yield and protein.

Experiment 1: Variety x N Management X PGR Split-split-plot design

• Spring wheat varieties (Main Plot) - AAC Brandon (CWRS) - AAC Cameron (CWRS) - Prosper (CNHR)

• N management (Split Plot) - 0 lbs N/ac

- 70 lbs N/ac urea at planting - 140 lbs N/ac urea at planting (standard) - 140 lbs N/ac ESN blend at planting (100:40, ESN:urea) - 140 lbs N/ac split N application (70 lbs N/ac urea at planting +

70 lbs N/ac Super U at flag leaf) • PGR Application (Split-Split Plot)

- Manipulator (0.73 L/ac) applied at the onset of stem elongation (GS 31)

Experiment 2: Plant Density X N Timing X PGR Split-plot design

Variety: AAC Brandon

• Plant Density (Main Plot) - Low: Target 150 plants/m2

- Medium: Target 250 plant/m2

- High: Target 350 plants/m2

• N Application Timing (Sub Plot) - 140 lbs N/ac urea at planting - 140 lbs N/ac split N application (70 kg lbs N/ac urea at

planting + 70 lbs N/ac Super U at flag leaf) • PGR Application (Sub Plot)

- Manipulator (0.73 L/ac) applied at the onset of stem elongation (GS 31)

2018 Preliminary Results

Plants Shoots Canopy Height DTM Yield Protein TKW

Variety plants/m2 shoots/plant cm days bu/ac % g

AAC Brandon 229 1.9 b 70.2x 77.9 a 80.9 a 14.2 a 33.6 b

AAC Cameron 210 2.0 b 85.9x 75.8 b 66.2 b 13.9 a 34.5 b

Prosper 204 2.2 a 73.5x 77.5 a 79.5 a 13.3 b 35.9 a

Nitrogen Management Strategies (compared to standard rate of 140 lbs N/ac urea at planting)

Reduced Rate (70 lbs N/ac) =y = = ↓ (-1.8) = ↓ (-1.04) =

ESN Blend (140 lbs N/ac) = = = = = = =

Split N (70 + 70 lbs N/ac) = = = = = ↑(+.45) =

PGR Application (compared to no PGR applied)

Manipulator (0.73 L/ac) = ↑ (+0.2) ↓(6.5) x ↑ (+1.2) ↑ (2.6) ↓ (-0.14) ↓ (-0.66) zMeans followed by different letters in columns are significantly different (P<0.05). yArrows indicate a significant (P<0.05) increase (↑) or decrease (↓) for a mean compared to the standard N treatment (140 lbs N/ac urea applied at planting) or compared to no PGR applied. An (=) indicates no significant difference. Numbers in brackets indicate the magnitude of the difference between means; xindicates a significant 2-way interaction between Variety and PGR (see Figure 1).

Table 1. Responses of plant counts, spike counts, shoots per plant, heights, DTM (days to maturity), yield, protein and TKW (thousand kernel weight) to main treatment factors in Experiment 1 averaged over two locations in 2018.

Table 2. Responses of plant counts, spike counts, shoots per plant, heights, DTM (days to maturity), yield, protein and TKW (thousand kernel weight) of AAC Brandon to main treatment factors in Experiment 2 averaged over two locations in 2018.

Figure 1. The differential height reduction of spring wheat varieties by PGR application averaged over two location in 2018

Summary

• There was no lodging present at trial locations during the 2018 growing season due to dry growing conditions (68-72% of normal rainfall).

• All varieties tested responded similarly to management other than PGR application, where the magnitude of response differed between varieties (Fig 1).

• Reduced rate of N decreased DTM and decreased grain protein content, while split N application increased grain protein content in both experiments, and increased DTM in Exp. 1.

• PGR application increased spike counts, shoots per plant, grain yield, and decreased TKW in Exp. 1. Canopy height and grain protein content were decreased in both experiments.

• Increasing plant densities resulted in decreased shoots per plant and DTM in Exp. 2. There were no significant differences in grain yield or protein content between plant densities.

Plants Shoots Canopy Height DTM Yield Protein TKW

Plant Density plants/m2 Shoots/plant cm days bu/ac % g

Low 123 cz 3.6 a 73.6 80.3 a 81.9 15.2 33.7

Medium 203 b 2.3 b 71.7 78.3 b 81.8 15.1 33.6

High 281 a 1.7 c 71.4 77.5 b 84.7 15.1 33.7

N Application Timing (compared to 140 lbs N/ac urea at planting)

Split N (70 + 70 lbs N/ac) =y = = ↑ (+0.9) = ↑ (0.6) =

PGR Application (compared to no PGR applied)

Manipulator (0.73 L/ac) = = ↓ (-4.4) = = ↓ (-0.3) = zMeans followed by different letters in columns are significantly different (P<0.05). yArrows indicate a significant (P<0.05) increase (↑) or decrease (↓) for a mean compared to the standard N treatment (140 lbs N/ac urea applied at planting) or compared to no PGR applied. An (=) indicates no significant difference. Numbers in brackets indicate the magnitude of the difference between means.

Data Collection and Analysis • Data collected to classify canopy structure and development during the

growing season included: plant counts, spike counts, canopy height, days to maturity (DTM) and dry matter and N partitioning (data not shown).

• Lodging ratings and stalk strength (data not shown) measurements were used to quantify lodging potential for each treatment.

• Harvest measurements included grain yield, grain protein content and thousand kernel weight (TKW).

ANOVA was performed using PROC GLIMMIX procedure in SAS version 9.4, with block nested within each location and both block and location considered a random effect in the model.