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The Role of Biostimulants in Enhancing Crop Resilience under Global Warming

global warming

Agriculture is intrinsically linked to environmental temperatures, and the recent trend of global warming has introduced a new set of challenges. Extreme heatwaves have become more frequent, leading to reduced crop yields and posing a significant threat to food security and agricultural sustainability.

 

Global temperatures have risen by 1.25°C due to intensified human activities, with estimates suggesting a further increase beyond 1.5°C within a decade. For every 1°C increase, the production of major crops like wheat, rice, corn, and soybean decreases by approximately 6.0%, 3.2%, 7.4%, and 3.1%, respectively. Understanding how plants adapt to and tolerate high temperatures is crucial for addressing the global food security issues exacerbated by global warming.

Plants have an optimal temperature range for growth, and thermal morphogenesis occurs under mild conditions, such as elongation of the hypocotyl and earlier flowering. Heat stress is defined not by an absolute temperature but by exceeding the plant’s optimal growth temperature by 5°C-10°C. The exact temperature receptors in plants have not yet been identified, but research has pieced together several clues:

1. Changes in membrane fluidity and protein conformation due to temperature shifts may be the first event in temperature perception.

2. Intracellular signals activate second messengers like calcium ions (Ca2+) and reactive oxygen species (ROS), transmitting heat signals to downstream responses.

3. Changes in intracellular proteins, such as the formation of heat stress granules that enhance thermotolerance, are part of the plant’s response.

4. Heat signals are further transmitted to the nucleus, regulating the expression of heat stress-related genes and synthesizing heat shock proteins and ubiquitins, which participate in key enzymatic stabilization and physiological activities under heat stress.

2. How Do Plants Cope with High-Temperature Stress?

Terrestrial plants are stationary and must contend with temperature fluctuations in their environment. They have evolved comprehensive mechanisms to combat heat damage:

1. Stomata as Thermoregulatory Windows:Stomata are the primary sites for photosynthesis, respiration, and transpiration, and they are among the first organs to respond to heat stress. Increased stomatal conductance and enhanced transpiration help cool the plant but can lead to excessive water loss and wilting.

2. Plant Hormone Regulation:  Various plant hormones, including abscisic acid (ABA), salicylic acid (SA), ethylene (ETH), and brassinolides (BR), are involved in the plant’s heat stress response. ABA accumulation during recovery from heat stress helps plants gain thermotolerance, while SA plays a crucial role in systemic acquired thermotolerance and hypersensitive response signaling.

3. Activation of Antioxidant Systems: High temperatures cause an explosion of ROS, leading to irreversible oxidative damage. Plants produce antioxidant enzymes like superoxide dismutase (SOD), ascorbate peroxidase (APX), ascorbate (AsA), and dehydroascorbate reductase (DHAR) to mitigate ROS damage and enhance thermotolerance.

4. Accumulation of Osmotic Regulators: Under high-temperature stress, plants accumulate osmotic regulators to enhance stress resistance. Exogenous application of substances like spermine, flavonoids, gamma-aminobutyric acid (GABA), proline, trehalose, sorbitol, glycine betaine, and polyamines can stabilize antioxidant enzymes and participate in ROS scavenging.

Other materials like S-ABA, alginate oligosaccharide, seaweed extract and brassinolide can also be used in crops’ stress tolerance.

3. The Role of Stress-Tolerant Biostimulants in Plant Thermal Stress

STB (Stress Tolerance Biostimulants) are a class of biostimulants that promote plant stress resistance. STB can activate the synthesis and accumulation of ABA in plants, enhancing their tolerance to high-temperature stress through stomatal regulation, ion regulation, osmotic adjustment, and reactive oxygen species modulation, facilitating post-stress recovery growth.

 

 

Global warming has become a major threat to food security and human development. STB, as an environmentally friendly and efficient biostimulant, plays a significant role in combating global warming, ensuring food security, and promoting sustainable agricultural development.

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