Climate
Percentage of the maximum water vapor content at the actual temperature.
What is relative humidity?
Example: 20C air temperature has a maximum water vapor content of 14.7 g/kg. If actual water vapor content is 10g/kg then: RH=10/14.7x100%=68%
The way to increase the anthocyanin production in our Red Leafy Crops
What is increasing the blue light ratio?
What are all three corners of the disease triangle?
1) Pest/Disease organism presence
2) Conducive environment for that pest/disease organism
3) Vulnerable host for that pest/disease organism to feed on
You’ll see lighter green color that turns to uniform chlorosis (yellowing) of older leaves. Severe stunting and yield decreases.
What is Nitrogen?
Causes: nutrient solution composition (<150ish ppm, too high Cl/S), irrigation strategy
FYI Sulphur (S): Uniform chlorosis across the entire leaf blade of young leaves.
Measure of the actual water vapor content in the air.
What is Absolute Humidity? We measure in grams of water per kilogram of air (g/kg), engineering gives us our AHU capacity in this number.
Methods to reduce Tip Burn in the plant at Harvest.
What is increasing the VPD (temp and RH), increasing irrigation, decreasing grow out days, increasing airflow, and changing varieties. We can also increase ramping times from day to night to decrease sudden changes in root pressure. Reduction in max DLI.
Having an intercanopy humidity of 99% is covered by which corner(s) of the disease triangle?
The conducive environment corner, since many foliar pathogens require water on leaves to propagate.
Presence of small necrotic spots and chlorosis on the margins of old leaves. Scorched leaf margins may lead to deformed leaves that curl downwards and appear wilted to the eye. Roots may be discolored and less vigorous.
What is Potassium (K)?
Causes: Irrigation strategy, nutrient solution composition (<250-300 ppm, K/Ca 1-2, K/Mg 4-5, K/N 1-1.5), low pH
May be confused with edge burn, which is caused by water stress or high EC. In this case veins will also become brown.
A diagram displaying the physical properties of water vapor in air depending on temperature and pressure.
What is a psychrometric chart? Useful for steering climate and understanding what the crop is experiencing.
We have bolting in many of the plants on the table.
What is decreasing the temperature or decreasing the grow out days?
Leaving doors to the grow zone open to the outside world is covered by which corner(s) of the disease triangle?
Pest/disease organism presence (letting them in the grow zone)
Plants will likely be stunted, with reduced growth speed. Leaf margins of older leaves may exhibited chlorotic regions followed by necrotic spots present after 4 weeks of deficiency.
Possibly exhibited on longer growouts: Leaves may be darker green than normal with purpling (typically on stems and undersides of leaves). Plants may exhibit rossetting.
What is Phosphorous (P)?
Cause: <20-30 ppm, Low rootzone temperatures, pH too high or too low, irrigation strategy, nutrient solution composition (too much Fe).
May be confused with potassium deficiency; or in extreme cases with excessive nitrogen, which also turns leaves dark green however, there will be no purpling and plants will not be stunted.
The corresponding temperature with the 100% saturation line for a known absolute humidity, the point in which atmospheric water vapor condenses to form liquid.
What is dew point temperature? 12g/kg has a dew point temperature of 16.7C, condensation will start to form on canopies, structural surfaces, and equipment inside the Growzone.
Variable of control we can change to decrease stretching in the lettuce leaves.
What is changing the density of plants per sqft, increasing the light intensity, and adding more blue light to the spectrum.
Accidentally dosing too much zinc sulfate in the nutrient mix and causing a zinc toxicity in the plants is covered by which corner(s) of the disease triangle?
Vulnerable host, especially for root pathogens
Scattered necrotic spots on young leaves and marginal necrosis and distortion of the youngest leaves. In severe cases roots will be brown with stubby laterals.
What is Calcium (Ca)?
Causes: irrigation strategy, nutrient composition (<180-240 ppm, K/Ca 1-2, Ca/Mg 4-8), pH too low or too high
AKA Tipburn
FYI may be confused with Boron deficiency.
The difference between the amount of moisture in the air and how much moisture the air can hold when it is saturated.
What is vapor pressure deficit (VPD)? A major tool for steering the crop and allowing for transpiration. Lower VPDs can cause crop defects that present as nutritional deficiencies, even if nutrients are balanced and abundant in the fertigate. High VPDs can cause plants to close stomata reducing photosynthesis and growth.
The method to increase the maximum capacity for Dissolved Oxygen in water that is 23C.
What is reduce the temperature to 18-21C. Alternatively we can add ozone, or bubbles to the water.
Which corner(s) of the disease triangle discourage us from propagating all of our plants from cuttings?
1) Pest presence: One sick plant can spread its disease over a large area through cuttings.
2) Vulnerable host: The cutting has an open wound and no roots yet.
3) Conducive environment: High humidity, low airflow, and high media saturation is favorable for many pathogens.
Mature leaves will exhibit light interveinal chlorosis and marginal necrosis becomes visible later.
What is Magnesium (Mg)?
Causes: Irrigation strategy, nutrient solution composition (K or Ca/Mg 4-8), pH too low or too high
FYI Iron (Fe): Interveinal chlorosis of new growth.