Waterlogging Effects on Yield and Photosynthesis in Eight Winter Wheat Cultivars

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Waterlogging Effects on Yield and Photosynthesis
in Eight Winter Wheat Cultivars

• Author M. E. Musgrave
• Presentation by Polly Longenberger

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Objectives

• Evaluate physiological performance of 8 winter
  wheat cultivars under waterlogged conditions
• Compare yield depression caused by waterlogging
  among the 8 genotypes

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Materials Methods

• Open ended greenhouse
• Similar temperature and day length to field in
  winter months
• Randomized complete-block design
• Split-plot treatments
• Waterlogging levels main plots
• Cultivars subplots

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Measurements

• Rootzone parameters
• Redox potential
• Temperature
• pH
• Quantified at 2-week intervals

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Measurements

• Apparent net photosynthesis
• Fully expanded flag leaves of each plant
• 12 measurements for each cultivar in each
  treatment
• Yield
• Grain weight, heads per pot, kernels per pot,
  kernels per head, kernel weight

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Rootzone parameters

• Free oxygen disappears at 350 mV, pH 7
• Different river silt sources influenced redox
  potential across the 3 yrs.
• Water logging had a small effect on soil
  temperature
• Soil pH values were influenced by waterlogging 2
  of the 3 yrs.

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Grain weight (g pot-1)

• Waterlogging caused substantial yield reduction
• Reduction in kernel number and kernel weight
• Cultivars responded equally to the stress
• Waterlogged performance in proportion to
  well-drained performance
• Cultivars differed with respect to yield
  parameters

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Photosynthesis definitions

• Net photosynthesis (assimilation) net uptake of
  CO2 into the leaf to be used for photosynthesis
• Leaf conductance measurement of the flux of H2O
  and CO2 through the stomata, in and out of the
  leaf

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Photosynthetic results

• Reduction in photosynethesis in the waterlogged
  treatment, 1990
• Reduction in leaf conductance, 1990 1992

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Correlations

• In 1992, yield (grain weight per pot) and
  assimilation rate were well correlated (r0.71)
• Across both years, avg. cultivar yields were well
  correlated with average assimilation rates
  (r0.71)

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Field study

• Sectioned off Coker 9877 field
• Waterlogged and well-drained sectors
• Conducted tiller counts
• Harvested yield

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Field Results

• Yield depression was similar to that which was
  observed in the greenhouse study
• Differences in weight per kernel, number of
  kernels, and number of tillers

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Conclusions

• Yield reduction due to waterlogging was evident
  across all 8 genotypes
• Assessment of a broader genetic range is needed
  to find tolerant cultivars

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