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Analysis Results

Plant Tissue Analysis

Introduction

The nutritional status of a plant may be determined by a chemical analysis of a specific part of a plant. Plant analysis may be used to verify a suspected nutrient element deficiency or to monitor its nutrient element status in order to evaluate the fertility program. A plant analysis can be useful in distinguishing between symptoms caused by physical, environmental factors. In evaluating plant abnormalities it is best when a comparison can be made between samples taken from normal plants and abnormal plants in the same area. Plant analysis is more effective when used in reference with a soil analysis.

Sampling Instructions

The accuracy of a plant analysis depends on how the sample is taken and handled. the following procedures should be followed:
  1. Only leaves or parts of plants of the same age and relative position on the plant should be sampled. A sufficient number of plants should be sampled to overcome the factor of plant variability (usually 20-30 plants).
  2. When sampling mixed stands (such as legume and grass mixture) the plant species should be separated. If no specific sampling instructions are given for a crop, a good general rule of thumb is to sample the upper most recently matured leaves.
  3. If a deficiency symptom appears, plants should be sampled as soon as the visual symptoms appear. Keep in mind that plants which have been under stress from some time may not give a true picture of their nutrient element status.
  4. Leaf samples should not be taken from plants obviously damaged by disease, insects, or chemical injury unless such damage is the objective of the study. Dead plant material should not be included in a tissue sample.

Handling a and packaging

  1. To avoid decompositions in transit, plant samples should be air-dried to approximately 10-20% moisture before shipment if possible.
  2. Soil covered or dusty leaves should be avoided if possible, but if leaves are dirty you may brush or wipe them with a damp cloth or was in very mild detergent solution and rinse in running water.
  3. Fresh plant tissue should not be placed in plastic bags or tightly sealed containers unless samples are dry. Heavy paper bags with perforations should be used.
  4. Fill out a sample information sheet for each sample submitted. If a recent soil test has been made, include the test results on the information sheet.
  5. Plant samples may be shipped first class, parcel post, air mail, United Parcel Service, air freight, or by bus. Select the best method of transportation considering time and cost variables.

Guide and Considerations for Interpreting Plant Analysis

  1. The timing of sampling as related to the stage of growth (i.e. young, early bloom, seed set, mature) and character of growth (i.e. slow, normal, rapid) should be known and considered when interpreting a plant analysis. The element content of a particular plant part can change considerably through the life cycle of most plants.
  2. Plants can develop unusual nutrient element contents due to periods of unusually wet or dry conditions causing very low availability of some essential plant food elements and excessive availability of other essential and non-essential elements. Other environmental factors such as temperature, light period and intensity should also be considered.
  3. Crop variety also bears consideration. Different varieties have different inherited characteristics and abilities to accumulate and utilize the essential plant food elements. For example, corn leaves from different varieties grown on the same soil and sampled at initial silk stage have shown nearly 50% deviation of some of the major element contents and more than 100 % deviation of certain minor element contents.
  4. The uptake by roots and the mobility of plant food elements between plant parts, in association with the rate of plant growth will affect the concentration of these elements in plant tissue. Element absorption and plant growth closely parallel each other during most of the vegetation growth period under normal growing conditions. But during very early growth and after seed set and development, the normal growth rate is interrupted and element concentration or dilution can occur. Nitrogen, phosphorus, potassium, are mobile in plants and will move from older tissue to newly developing parts in order to supply the amount needed for growth.
  5. The application of N-P-K fertilizers or limestone to soils can significantly alter the concentration of more than one element in plant tissues and may lead to deficiencies or toxicities of other elements.