Though our crop plants need adequate sunlight, they can only take so much heat. The plant tissues die normally around 115°F. The plant temperature is just usually above air temperature. But in certain conditions, plant temperature can rise to the critical level.
Plants, in general, have three major ways to remove excess heat.
1. Through long wave radiation
2. Through heat convection into the air
3. Through transpiration
If either any of these major ways are interrupted, plant temperature can rise above the normal.
For instance, transpiration can be interrupted by inadequate water, injury, vascular plugging, and stomatal closure. When that happens, the major cooling mechanism of the plant is lost.
Take note that dry soil conditions can also lead to excess plant heating. When the soils are dry, roots produce ABA or Abscisic Acid. This acid is transported to leaves which signals stomatal closure.
How to protect your crops from heat damage:
- Overhead watering is the major method to reduce plant heat stress. Always make sure that you have sprinklers set up and you provide adequate water supply.
- Misting also helps in improving your plant’s temperature. It helps in lessening water vapor pressure deficit.
- You can also increase dissipation and reflection of radiative heat using reflective mulches.
- Low density and organic mulches like straw can also be used to conserve moisture and reduce surface radiation.
- If you are located in very hot areas, use shade cloth for partial shading. This will help in reducing heat and radiation.