We are currently facing quite warm, sunny weather in western Europe. This causes quite some headackes for a lot of growers. Lots of berries to pick, but how to keep the quality good and the and the crop fresh, active.
With the sunny weather we see the drain EC’s climbing, crops ageing, berries getting smaller and shelf life going down.
Yes temperatures are high, but is it all because of the temperatures? Increasing EC’s show another direction also: not enough water.
Looking at the roots, this connects: also the roots show there is not enough water for a lot of strawberries. Yes the numbers are right: average drain percentages 30-40%. As my professor mentioned: no bigger lie as an average. This is supported by weighing gutters: in the morning and afternoon enough moisture content, at the heat of the day, moisture contents drop, so does the drain percentage.
Below a picture of the roots of such strawberries: around the dripper: a nice amount of white roots. Between the drippers only at the bottom of the buckets. And if we measure the EC: between the drippers high – going up to 3, just below the drippers: normal 1,5-1,8.
The crop below shows it also: they can’t handle the lower moisture content in the heat of the day, just as it is needed the most. This causes ageing of the leafs.
Problem
The relation between radsum and evaporation is not lineair. In the lower radiation the evaporation is relative lower and in the higher radiation – the heat of the day – the evaporation is relative higher.
Solution
Most irrigationcomputers can set influences on the shot size. A setting can be: from 500-1000 Watt add + 20-% on your shot size.
In that case the morning and the late afternoons still have the normal shot size. But in the heat of the day in stead of for example 400 ml/shot/linear meter a shot of 480 ml/linear meter is given.
This helps the plant in the water uptake. And we see EC’s don’t increase so much in the hot summer period. Plants stay fresh and active, fruit quality improves.