Photosynthesis and respiration are two main processes that sustain plant life, including almond trees.
Photosynthesis is the process by which plants convert light energy into chemical energy, storing it as glucose (Carbohydrate). This process occurs primarily in the chloroplasts of plant cells, which contain chlorophyll, the pigment responsible for absorbing light. During photosynthesis, carbon dioxide (CO2) is absorbed from the atmosphere through the plant's leaves, and water (H2O) is taken up by the roots from the soil. Light energy, typically from the sun, drives the conversion of these inputs into glucose (C6H12O6), which serves as an energy source for the plant, and oxygen (O2), which is released as a byproduct.
Respiration is the process by which plants and other organisms convert glucose into usable energy. During respiration, glucose and oxygen are broken down to produce carbon dioxide, water, and energy. This energy is used to fuel various cellular activities, including growth, Reproduction or Crop and environmental protection (Heat stress). While photosynthesis primarily occurs during the day when light is available, respiration occurs continuously, both day and night.
The interplay between photosynthesis and respiration is crucial for the health and productivity of almond trees, enabling them to grow, produce almonds, and sustain their life cycle. We have only 30 weeks of a growing season to capture all the energy for the year to produce that big crop the following year.
There are many things that we can do to maximize our trees to capture the maximum amount of light energy every day. Number one is Irrigation needs of the tree. Almond trees use very little water in March through part of April then it ramps up very quickly and peaks in the first and second week of July then starts going down until October November where it's using very little again.
Photosynthesis increases when the sun comes up, peaks out in the middle of the day and gradually decreases as the sun sets in the west. Respiration occurs at night and more in the day. When the day gets warmer, and we have above average temperatures the tree requires more energy or respiration to cool itself. When we have a heat wave and temperatures stay above average, photosynthesis goes down and the tree goes into a negative state, which is using more energy than it’s making from photosynthesis.
See the graph below showing photosynthesis and respiration during the day when temperatures increase. You can see when temperatures get above 90 degrees Photosynthesis starts to go down and respiration continues to go up to the point where respiration is higher than photosynthesis. This is where the tree is in its negative energy state. This is not good and the more time the tree is in this negative area the less total carbohydrates that it makes and stores to produce these large crops year after year. Last year we had over 55 days over 100 degrees.
This is absolutely the most important thing that we can do as almond producers, is to keep out of that negative area as much as we possibly can. There are many cultural practices that we can do to lessen the time our trees are in this negative state. Like I said earlier, watering your orchard perfectly is the most important. There are lots of aspects to irrigation that make this difficult or easier. This seems simple to give the tree the exact amount of water that it needs. However, it can get very complicated depending on how your irrigation system performs, or your soil quality, the depth, your slope, water infiltration rate, water quality, organic matter and biodiversity of your soil.
All of these play a factor in how fast you and your plants can react when abnormal heat stress is in the weather forecast. The second, most important factor is soil nutrition. We monitor soil and tissue by sampling to keep these levels in their optimum nutrition levels. Maybe being tied with soil nutrition is the levels of Microbes and biodiversity in our soils. In the last 10 years we’re finding that it is very important to have your soil high in organic matter with high biodiversity. Plants have evolved with microbial activity in the soil to release nutrition to the roots at the precise timing of the plant’s needs. This is also related to keeping the tree stress free during heat in the summer. 3rd most important is Diseases and other pests. 4th is foliar nutrition.
Just remember we have about 30 weeks per year to get as much light energy out of the sun as we can.
We don’t want to miss any of those days because of excess stress that we could have mitigated with optimum irrigation.
Dirk Ulrich - 209-531-6662 - dirkulrich55@gmail.com
Jesse Penick - 209- 678-8887 - jesse@ulrichag.com
Daniel Vann - 209-617-3879 – daniel@ulrichag.com
Nicole Groathouse – 209-646-4818 – nicole@ulrichag.com
Emmanuel Moreno – 209-408-3542 – emmanuel@ulrichag.com