Plant leaf analysis is a management tool that starts with a great sample

Thanks to the rains and sunny weather, crops are showing great potential. But this is also the time when you begin to see possible nutrient deficiency symptoms and you might use plant tissue analysis for diagnosis. You could also be using tissue analysis on a regular basis to manage and adjust your crop's fertilizer program.

Here are 7 points to remember when collecting and submitting plant tissues for analysis:

1. Variation, variation, variation A plant's nutrient content is not constant. It can vary hourly, daily, and monthly. It is different between older and younger leaves, sunny and shaded leaves, from the base of the leaf blade to the tip and margins, and between plants. Young plants parts are undergoing rapid changes in nutrient content while those past full maturity should not be sampled. When in doubt, always select the upper, most recently matured leaves.
2. Sample a specific plant part and at an identified growth stage Collect plant tissues for which you have interpretive reference values for a specific stage of growth. Sampling a different plant tissue or at a different time makes interpretation of the results difficult. Be consistent in the tissues you select for analysis.
3. Diagnostic comparisons When using plant tissue analysis for diagnostics collect from plants showing symptoms and from healthy plants growing within the same area. The healthy plants provide you with a reference point. To make the most of your diagnosis ensure that samples collected are as similar as possible (age, stage of growth, location on plant). Analysis is done on a dry weight basis; make sure you submit the same weight.
4. The more, the merrier or at least more representative Increasing the number of individual plants represented in the submitted sample, improves the analysis for the field being evaluated. This will help manage the naturally occurring variation between plants within the field. It is better to include more individual plants for sampling than to collect more tissue from fewer plants.
5. A good analysis report starts with a good sample Avoid collecting from plants that:
   • have been under long climatic or nutritional stress
     
   • damaged mechanically, insects or diseased
     
   • covered with dust or foliar sprays
     
   • are border row plants or shaded leaves within a canopy are dead.
6. Add in a soil test Completing a soil test at the same time you take the plant tissues will help in interpreting the results. Take the soils from the same area you collected the plant tissues. If using diagnostic tissue analysis, submit separate soil samples from healthy and affected plants.
7. Handling plant tissues after collecting:
   • Make sure leaves are not contaminated with any chemicals or dust after collection.
     
   • Do not store in plastic bags
     
   • Deliver to laboratory within 24 hours. If delivery will take longer than 12 hours, cool tissues to 5°C or remove excess moisture by air drying. Tissues can also be oven dried at 80°C.
   • Lower temperatures will not remove all water from tissues. Higher temperatures can result in thermal decomposition.

Keeping these points in mind will help you in getting accurate results back on your tissue analysis report. With a good report in hand, you can make an informed management decision.