In the Washington area, apple growers have begun adjusting their irrigation practices to achieve their fruit's desired size at the end of the season.
But trying to control a biological process with so many uncontrolled variables (variety, soil, weather, specific block characteristics) by manipulating irrigation is a challenge.
Over the years growers have developed tactics for achieving their size goal based on past experience, the season's timing, climate conditions and of course examining closely their fruits. Some of them start this complex process 2 months prior to harvest. Imagine throwing a basketball from half court when the lights are out and the ball changes in diameter.
But it's a whole different ball game when our customers see in real-time, on their mobile, their apples size via our fruit sensors and can compare it to Phytech's target curve (generated from the desired fruit size). The picture is completed with direct data both from the tree (growth rate/MDS/water demand) and the irrigation system (pressure).
Now, instead of flying blind ,it's more like a video game, where you aim your shot with a trajectory and can adjust the ball movement while in the air. Let's see how its done:
At the beginning of the season the grower sets his target fruit size and the system produces a target curve. During the season, our fruit sensors measure fruit size in real time. That information is translated into the orange trajectory curve - the actual path the "fruit" takes on its way to the final destination. By presenting these 2 curves on one screen our fruit growers get clear visibility in real-time of what needs to be done to get the fruit back on the track.
Fruit is too big and above the target curve? It's time to switch to regulated deficit irrigation, creating mild-to-moderate stress that will slow the tree growth - and its fruits. Fruit is too small? growers can apply more water to avoid stress conditions and help boost fruit size.
A fruit size radar
But how do growers calculate just how much to over/under irrigate to navigate their fruit back on track? At this point, the irrigation system pressure feedback comes in handy, as growers can easily observe the effect of their actual water delivery on the fruit's trajectory.
The final piece of data that helps generate a clear "fruit size radar" comes from the tree. The trunk growth and MDS (Maximum Daily Shrinkage) graphs give grower instant feedback of how the tree reacts to the change in irrigation. Plant status is another visual layer to help growers understand the effect of their irrigation and maintain the delicate balance between achieving their desired fruit size while keeping the tree healthy. It's especially important when applying deficit irrigation as cutting water supply might harm the tree and affect its future productivity.
Check out the video for real-life examples of how customers are using the system