How does the Mn and P-tester work?
Phosphorus (P) and Manganese (Mn) are essential nutrients for all plants, however if the availability of Mn and/or P in soil is insufficient to cover the needs, deficiency results in reduced growth and low harvest yields of grains, seeds or fruits.
With the integrated Mn and P-tester, you can take measurements on plants directly in the field, and in seconds determine whether the nutritional status of Mn and P is adequate. The handheld device is calibration free and transmits the measurements directly to your smartphone (Iphone). Using easy understandable graphics, you get instant answers on whether the plant is well supplied; on the border to deficiency or if the plant lacks Mn or P to an extent requiring fertilization.
The integrated Mn and P-tester builds on a new principle for measuring plant nutrients. Mn and P play a key-function in photosynthesis, by catalysing water splitting and in ATP synthesis, respectively. Both processes are specifically dependent on Mn and P and just marginal limitations in the availability of Mn and P leads to metabolic disturbances, which can be picked up by the integrated Mn and P-tester. These processes are identical in all plants and consequently there is no need for calibration and data processing – all data coming out of the integrated Mn and P-tester are ready for interpretation and easy to understand.
The P status of the plant is measured using the estimate “P-predict”. The value is on a range from 0 to 1, with a P deficiency threshold at 0.50.
The Mn status of the plants is measured using the estimate “Mn-predict”. The value is on a range from 0 to 100, with a Mn deficiency threshold at 80.
The Mn and P-tester can measure much more than just nutrient deficiency
Plant growth and vitality can be affected by many factors such as drought, cold, heat, pathogens and various nutrient deficiencies. If plants are stressed by one or more of these factors, it affects the ability of plants to utilize sunlight in photosynthesis. In addition to measuring the effects of Mn and P deficiency on photosynthesis, the integrated Mn and P-tester also measures the ability of photosynthesis to utilize light (photons), and it measures if the energy transfer between the many processes of photosynthesis is ideal or inhibited by one or more stress factors. These measurements are carried out in parallel with the Mn and P measurements, and results are presented in a way that makes them easy to interpret.
The Mn and P-tester measures the following vitality parameters:
Photosynthetic Efficiency (Fv/Fm): In an unstressed plant, regardless of species, the value for Fv/Fm must lie between 0.75-0.85. If the value is less than 0.75, it reveals that the light is not utilized optimally in photosynthesis and that the plant’s growth is weakened. If Fv/Fm is reduced over a long period of time, the plant will become susceptible to diseases that develop discolouration (necrosis) and the harvest yield and quality of the crop will decrease. There are many stress factors that can potentially reduce photosynthetic activity, and the measurement does not provide any information about what is wrong – it only informs if something is wrong. If the value is less than 0.75, systematic work must be done to find the cause of the plant’s discomfort using good farming practices. Photosynthesis efficiency is a very sensitive measurement that gives the opportunity to follow the plants’ well-being and optimize its growth conditions, and is thus one of the strongest parameters the plant grower can have at his disposal.
Plant vitality-index (PI): This parameter represents a measurement of the energy transfer between the plant’s two photosystems (photosystem II and I). The PI value for a healthy plant will always be greater than 2.5 – If the value is lower, the plant will be stressed. Often the PI value will follow the Photosynthesis Efficiency (see above), but PI has been shown to be more sensitive to certain types of stress, such as drought and heat. Therefore, PI is a very useful parameter if the growth conditions are to be optimized.
