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Corn Leaf Orientation Response to Plant Density

 

Corn Leaf Orientation Response to Plant Density

Background and Objectives

  • Previous research has shown that corn plants can alter their leaf orientation in response to their environment (Girardin, 1992; Maddonni et al., 2001; Maddonni et al., 2002).
  • Leaves may preferentially orient toward the inter-row in order to optimize capture of sunlight.
  • A research study was conducted in 2015 to evaluate leaf orientation response to plant density with 2 Pioneer® brand corn products.

Study Description

Location:    Johnston, Iowa
Replicates:   4
Plot Layout:   Small plots (10 x 17.4 ft), RCBD
Row Width:   30 inches
Row Direction:   North-south
Planting Date:   May 19, 2015
Factors:
  • Pioneer® brand corn products
     
       Hybrid/Brand¹:    P1151AM(AM, LL, RR2)
    P1311AMXT™ (AMXT, LL, RR2)
     
  • Population: 30,000, 40,000, and 50,000 plants/acre

Hybrids were selected to represent contrasting leaf types: Pioneer® P1151AM™ brand corn had more upright leaves than Pioneer® P1311AMXT™ brand corn in 2014 research.

Leaf Measurements

  • Leaf orientation measurements were taken on the 2nd, 6th, 10th, and 14th leaf of 10 plants in each plot.
  • Leaf orientation was measured using a compass smartphone app.
    • 0º and 180º = parallel to the row
    • 90º and 270º = perpendicular to the row
    Corn leaf orientation measured using a compass smartphone app.

Results

  • Leaf orientation distribution did not significantly differ between corn products or among population densities.
  • Leaves tended to orient more toward the inter-row with successive growth stages (Figure 1).
    • Preferential orientation toward the inter-row was apparent at leaf 6, indicating that plants were responding to neighboring plants at relatively early stages of vegetative growth.
    • These results are consistent with previous research that has also detected nonisotropic structure in corn plants as early as the 6th leaf (Girardin, 1992).

      Distribution of azimuthal orientation for leaf 2, leaf 6, leaf 10, and leaf 14 averaged across corn products and population densities.
      Figure 1. Distribution of azimuthal orientation for leaf 2, leaf 6, leaf 10,
      and leaf 14 averaged across corn products and population densities.
  • Azimuthal orientation of leaf 6 showed little correlation to the orientation of leaf 2 (Figure 2).
  • Orientation of leaf 10 showed a much stronger relationship to the orientation of leaf 6 (Figure 3), as did leaf 14 to leaf 10 (Figure 4).
  • These results suggest that leaf orientation response of corn plants to neighboring plants occurred largely during early vegetative growth between V2 and V6, after which leaf orientation was relatively static.

    Azimuthal orientation of leaf 6 compared to leaf 2 for all corn plants sampled.
    Figure 2. Azimuthal orientation of leaf 6 compared to leaf 2 for all plants sampled.

    Azimuthal orientation of leaf 10 compared to leaf 6 for all plants sampled.
    Figure 3. Azimuthal orientation of leaf 10 compared to leaf 6 for all plants sampled.

    Azimuthal orientation of leaf 14 compared to leaf 10 for all plants sampled.
    Figure 4. Azimuthal orientation of leaf 14 compared to leaf 10 for all plants sampled.

Conclusions

  • The results of this study demonstrate the ability of corn plants to adjust their leaves in response to their environment.
  • Future efforts to optimize the crop canopy for maximum light utilization and yield need to take this effect into account.
  • Results suggest that attempts to optimize corn leaf orientation through seed positioning at planting may have limited benefit due to the inherent ability for plants to adjust themselves in response to their environment.

References

Girardin, P. 1992. Leaf azimuth in maize canopies. Eur. J. Agron. 1: 91-97.

Maddonni GA, Otegui ME, Cirilo AG. 2001. Plant population density, row spacing and hybrid effects on maize architecture and light attenuation. Field Crop Res. 71: 183-193.

Maddonni GA, Otegui ME, Andrieu B, Chelle M, Casal JJ. 2002. Maize leaves turn away from neighbors. Plant Physiol. 130:1181-1189.

Authors: Mark Jeschke and Adelyn Uppena


¹All Pioneer products are hybrids unless designated with AM1, AM, AMRW, AMX, AMT and AMXT, in which case they are brands. 2015 data are based on average of all comparisons made in one location through August 17, 2015. Multiyear and multi-location is a better predictor of future performance. Do not use these or any other data from a limited number of trials as a significant factor in product selection. Product responses are variable and subject to a variety of environmental, disease, and pest pressures. Individual results may vary. PIONEER® brand products are provided subject to the terms and conditions of purchase which are part of the labeling and purchase documents.

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