Factors affecting plant perception include light, sound, touch, moisture, temperature, and magnetism. Plants recognize and adapt to changes in the environment on a cellular level via complex interactions of genes and receptors that identify external stimuli. The study of plant perception has gained international interest to address population growth and climate change affecting food production.
Scientists have discovered that epidermal cells in plants perceive disturbances in the air from sound, light, and moisture. These cells communicate on a molecular level through genes, which react independently or in tandem to adapt and permit survival. Researchers successfully isolated specific receptors that regulate certain stimuli, but the complicated process is not fully understood.
Plant perception includes light sensors to determine day from night and identify harmful ultraviolet rays. Three photo receptors work together and adapt to environmental light at different stages of growth, including germination, flowering, and the dormant stage. Molecular adaptations also produce pigments to filter out ultraviolet rays, essentially creating a natural sunscreen.
Biocommunication in plant cells fosters plant perception when insects, bacteria, or fungi pose a threat. Some plants produce a toxin that kills infected cells to prevent the spread of damage. They might create an odor that alerts nearby plants of the threat, enabling them to begin producing toxins. A similar process increases certain acids to ward off parasitic plants that invade the environment.
Plant perception also triggers a response to touch, sound and magnetic fields. A hormone called gibberellic acid might affect growth rates in plants exposed to certain wavelengths, frequencies, or vibrations. Plants also adapt to wind by growing stronger or more flexible. In one study on magnetism, the roots of plants grew toward the source, while stems grew in the opposite direction.
Studies on plant perception related to drought show that a network of genes interact to use water more efficiently when water is scarce. One of these genes reduces the rate of transpiration of water into the air through leaves and stems. This same process might allow plants to resist salinity in water and use nutrients more effectively. Researchers believe these defense mechanisms reduce crop yields because of the energy required to produce short-term adaptations or molecular changes.
Plant perception differs from sentience, the belief that plants have emotions capable of registering fear, pleasure, and pain. These concepts became popular in the 1960s when the U.S. researcher Cleve Backster attached lie detector devices to house plants. He claimed paranormal biocommunication possible between plants and humans. This theory is not recognized as scientifically valid because plants lack a central nervous system, and Backster’s results could not be replicated.