Potato Review Group

Contents

Use of petiole samples

Taking petiole samples

Target concentrations of nutrients in petiole samples

 

Use of petiole samples

  1. Use petiole samples for analysis of nitrogen (as nitrate-N), phosphorus and potassium.
  2. Use whole leaf samples for other nutrients.
  3. Samples should be taken from the youngest fully expanded leaf.
  4. The earliest time a sample can be taken is when a plant has 6 – 8 leaves.
  5. Early sampling may enable remedial action to be taken if a nutrient is deficient.
  6. Use the data below to check nutrient levels.
  7. Do not use threshold levels from the laboratory, as these do not account for the stage of development of your crop.
  8. If a nutrient is deficient, check the appropriate page for further information.

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Taking petiole samples

  1. Walk across a field in a “W” pattern, taking samples of the youngest fully expanded leaf.
  2. The youngest fully expanded leaf is generally the fourth leaf below the growing tip.
  3. A potato leaf is a compound leaf comprising a central petiole / midrib and leaflet blades.
  4. Remove the whole leaf from the stem.
  5. Strip off and discard the leaflet blades.
  6. A sample should comprise sufficient petioles to fill a standard 1/2 pint mug.
  7. More leaves will have to be picked to make up a petiole sample than a whole leaf sample, particularly early in development when leaves are small.

Potato tissue samples

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Target concentrations of nutrients in petiole samples

Nitrate-N

Petiole nitrate data

Further information on nitrogen.

 

Phosphorus

Petiole P data

Further information on phosphorus.

 

Potassium

Petiole K data

Further information on potassium.

 

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