What is the best measurement for knowing how “thirsty” a plant feels?
Water potential is the best measurement in understanding the level of “thirst” a plant feels, especially when it is measured directly inside the plant. The performance of plants (growth, opening of stomatal pores on leaves to allow photosynthesis and evaporative cooling, movement of sugars and minerals, etc.) depends on the plant’s water potential, which is the plant’s ability to draw water from the soil. For this reason, we developed the FloraPulse microtensiometer – a special sensor that goes directly into the plant and can provide day-to-day water potential measurements.
What is a microtensiometer and how do we use it?
A microtensiometer is our patented plant sensor that is in direct contact with the plant, and thus is able to track day-to-day water potential of the plant. The measurements that the microtensiometer takes are stored in a datalogger as part of the installation. The datalogger uploads the measurements to the cloud and ports the data to the end-users.
Figure 1. The microtensiometer in the field.
How have you tested the sensor?
FloraPulse has done months-long field trials in winegrapes, almonds and apple. We corroborated that our patented sensor measures plant water-stress accurately and that our measurements agree with the gold standard: the pressure chamber. As a result, our sensors could save growers on time and effort in measuring plant stress manually in the field.
Field trial in Matchbook Winery, Merlot winegrapes:
Field trial in Done-Again Farms, nonpareil almonds:
Is it true your sensors captured the solar eclipse?
Yes. Our sensors captured the increase in water potential in almond trees when the moon blocked the sunlight on August 21, 2017 from 9:30 am to 11:45 am. Notice the bump in measured water potential in the plot below.
Does the sensor damage the plant?
Sensors have been installed sensors into almonds, grapes, and apple trunks for multiple years. We have not seen evidence of any detrimental effects on the plant. Nonetheless, to minimize issues, sensors should be installed in vines or trees with trunks larger than 2” in diameter.
What is the minimum branch size for sensor install?
We recommend installation in branches or trunks at least 2” in diameter.
Can the sensors withstand a tree shaker?
Our limited testing indicates that the sensors can go through the nut shaking process without issue.
Do you need one in every plant?
No. When a new field is set up, irrigation blocks are shaped so that the soil and plants in each block have similar characteristics and thus will have similar water status. We recommend the use of 1-3 sensors per irrigation block to get a good average of the block water status. It would be logical to install the sensors at or near the sites you have used for pressure chamber monitoring.
Do you need cell reception?
Our current datalogger uses a cell modem to send the sensor information to the cloud. For this reason, we currently can only install sensors in areas with good cell reception. We are developing loggers that do not require cellular reception.
How long does the sensor last?
We have tested and expect the sensors to last longer than a growing season. More testing is under way to see if the same sensor can be reused for multiple growing seasons. We currently recommend that new sensors be installed at the beginning of each year.
What is the difference between water content versus water potential?
When dealing with any wet material such as soil or plant tissue, there are two important properties related to water. Water content is how much water the material holds, expressed as 30% water or 0.3 grams of water per cubic centimeter of soil. The water potential is how tightly the tissue holds the water. This can be illustrated by thinking of a sponge and a chunk of clay. It is easy it is to squeeze almost all the water out of a wet sponge, but much harder to squeeze of out of the wet clay even though both may have the same water content when wet.
Do you gather data over the winter?
Yes – the sensors measure the plant water status over the winter, even when there are no leaves. This data helps ensure that plants are not water-stressed when the growing season re-starts in the spring.
Which crops have been validated?
Grapes, almonds, prune, cherry, mango, apple, corn.
How much do the sensors cost?
The sensors are sold on a subscription basis, at $1,500/year/installation. This is an all-inclusive cost that includes the sensor probes, datalogger, installation supplies, mailing costs, cellular data, data visualization, and warranty. If the system malfunctions because of a failure in our hardware, we will replace it or mail you a replacement free of cost.
Where can I learn more about your system?
Download the FloraPulse 2020 customer info sheet.