Olive Lights

In one of the gatherings of knowledge, after the evening (Isha) prayer at the Al-Suyuf Mosque in Alexandria, the mosque's sheikh sat to contemplate the verses of the Holy Quran with the worshippers, and a part of verse 35 in Surat An-Nur caught our attention: (from a blessed olive tree, neither of the east nor of the west, whose oil would almost glow even if untouched by fire).

The discussion revolved around the magnificence of the metaphor in this verse. As I advanced in my professional career and specialization in vegetable oils, and olive oil specifically, I tried to connect the noble verse with the scientific interpretation of olive trees. The discussion was about how the olive tree, located in an ideal place between East and West, is reached by the sun wherever it is planted, and its oil increases in purity and clarity until "its oil would almost glow," meaning that the oil of this tree is blessed and very pure, almost glowing from the intensity of its purity even before fire touches it. It is worth noting that the flash point of olive oil is (190 – 207) degrees Celsius.

Looking into scientific research, we noticed the existence of a natural physiological phenomenon in plants, including olive trees, which is the phenomenon of chlorophyll fluorescence.

So what is this phenomenon?

The basis of this phenomenon is that the chlorophyll present in the plant's foliage does not convert all the absorbed light energy into chemical energy during the process of photosynthesis; part of this energy is lost in the form of heat, and another part is re-emitted in the form of a weak red light called "chlorophyll fluorescence."

And what is its importance for olive trees?

• It can be monitored with special devices that measure fluorescence emission when leaves are exposed to light.
• The intensity of fluorescence changes according to the state of the photosynthesis apparatus, especially the activity of Photosystem II.
• When olive trees are exposed to stress (such as drought, salinity, high heat, or disease infections), this is reflected in the patterns of chlorophyll fluorescence; the efficiency of light conversion decreases and the proportion of lost energy increases.

What is Photosystem II?

During the process of photosynthesis in the plant, part of the light interacts with a complex protein compound in the plant membranes known as Photosystem II. This system converts light energy to split water molecules, producing electrons used in the process of photosynthesis, protons that contribute to producing energy (ATP), and oxygen that is released into the atmosphere. We mentioned in a previous article that olive trees are considered a carbon sink, preserve the environment, and are resistant to climate change. (You can refer to the previous article here: Olives and the Carbon Footprint)

Why is measuring chlorophyll fluorescence an important indicator in olives?

The importance of measuring this phenomenon in olive trees lies in the following purposes:

• Assessing the tolerance of olive trees to drought or salinity.
• Monitoring the effect of agricultural treatments (fertilization, irrigation, pruning) on the efficiency of photosynthesis.
• Early detection of infections or environmental stresses before clear visual symptoms appear.
• Comparing different olive varieties in their ability to tolerate stress, or evaluating the success of a particular agricultural treatment for one variety over another.

In short: chlorophyll fluorescence is a general phenomenon in plants, but the olive tree has become a model plant in research related to it due to its economic importance and its exceptional ability to withstand difficult conditions.

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