Plant analysis provides important information about the nutritional value, quality, and current condition of plants. Inductively Coupled Plasma – Optical Emission Spectrometry (ICP-OES) and Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) are two of the most used laboratory techniques. But these techniques require tedious sample preparation, more expenses, and more time. This led to the development of rapid techniques which can help in on-site decision making.
One such technique involves the use of cardy meter. Using this instrument can give results on the field in a few minutes. This is based on ion-selective measurement and its results correlate well with standard colorimetric methods. The use of cardy meter can help in the analysis of plant petiole sap for nutrients such as potassium, sodium, and nitrate-nitrogen. Information obtained from the analysis can help in assessing the plants’ needs for fertilizers.
The use of cardy meter starts with pressing the sample to get a liquid specimen and then applying it on the sensor pad of instrument. A stable reading is shown after 30-45 seconds. Calibration of the instrument prior to each measurement will help in getting accurate results.
Another rapid testing technique involves the use of a chlorophyll meter. Measuring the leaf chlorophyll content is an indirect way of determining the crop nitrogen status in plants. The procedure starts with clamping a leaf blade with a sensor and applying two different light wavelengths to the clamped area. The first wavelength (650nm) is sensitive to chlorophyll activity. The second wavelength (940nm) is for internal instrument calibration. Measurements are recorded according to transmission of reflected light.
X-ray fluorescence (XRF) is another rapid instrumental technique. There are portable XRF instruments that can be used for field testing. This technique shows good correlation with classic laboratory measurements for calcium and potassium. XRF also shows potential in precise and rapid analysis of iron, phosphorus, sulfur, manganese, and magnesium.