Plant Growth Regulators for Growth Promotion and Stress Resistance: Functions and Mechanisms

Plant growth regulators (PGRs) that promote growth and enhance stress resistance are a class of highly active, low-dosage substances that serve a dual purpose: they stimulate crop growth and development while bolstering the plant's ability to withstand environmental stress. By regulating the balance of endogenous plant hormones, these agents help crops establish strong, healthy growth while enabling them to cope with adverse conditions—such as low temperatures, drought, or phytotoxicity—making them essential tools for ensuring stable yields and high-quality produce in modern agriculture.

Core Mechanisms of Growth-Promoting and Stress-Resistant PGRs

Growth-Promoting Mechanisms: These regulators modulate cell division and elongation, increase chlorophyll content, and enhance photosynthetic efficiency. They can break seed dormancy, stimulate root system development, and accelerate nutrient uptake and utilization, effectively addressing issues such as stunted growth, weak seedlings, or slow recovery after transplanting.

Stress-Resistance Mechanisms: These regulators induce the production of stress-response proteins and optimize cellular osmotic pressure and hormonal balance. This allows crops to maintain normal metabolic functions under adverse conditions—such as cold, drought, or high soil salinity—while also helping to mitigate damage caused by external factors like herbicide exposure or excessive fertilizer application.

Key Types of Growth-Promoting and Stress-Resistant PGRs and Their Specific Functions

14-Hydroxylated Brassinosteroid
Growth-Promoting Effects: A naturally derived, broad-spectrum regulator that promotes cell elongation and division, boosts photosynthetic efficiency by over 20%, supports flower and fruit retention, and encourages uniform fruit enlargement. In field trials, it has been shown to increase the yield of winter jujube by 15% per plant.
Stress-Resistance Effects: It triggers the production of stress-response proteins, helping crops withstand extreme weather events such as cold snaps or "hot, dry winds" (desiccating winds), thereby significantly reducing the risk of yield loss. It also facilitates rapid recovery from various forms of phytotoxicity.

Diethyl Aminoethyl Hexanoate (DA-6)
Growth-Promoting Effects: Increases chlorophyll content and accelerates the sprouting of new shoots. When applied during the seedling stage, it helps weak plants recover quickly; it can also be combined with foliar fertilizers to significantly improve nutrient utilization efficiency.
Stress-Resistance Effects: Enhances the crop's tolerance to low temperatures and drought. It helps maintain cellular activity even in cold environments, preventing the growth stagnation that typically occurs when temperatures drop. S-Abscisic Acid (S-ABA)
Growth-promoting effects: Regulates nutrient distribution within crops, promotes uniform fruit coloration, improves quality, and increases the proportion of marketable produce.
Stress-resistance effects: Acts as a natural stress-response hormone that rapidly induces stomatal closure, reducing water transpiration. It significantly enhances tolerance to drought, cold, and saline-alkali conditions, serving as a key stress-regulation agent for crops in arid regions.


Sodium Nitrophenolates (Atonik)
Growth-promoting effects: Breaks seed dormancy; soaking seeds can accelerate germination by 2–3 days. Root irrigation after transplanting significantly shortens the recovery period, helping to revive stunted, yellowed, or weak seedlings.
Stress-resistance effects: Stimulates cellular vitality, maintaining root activity even in low-temperature, low-light environments. It reduces the incidence of root rot and seedling mortality, while bolstering the crop's overall resilience to stress.

Gibberellic Acid (GA3)
Growth-promoting effects: Breaks dormancy in seeds and tubers, promotes stem and leaf elongation, and induces parthenocarpy (fruit development without fertilization). When used on grapes, it can produce seedless fruit and improve fruit-set rates.
Stress-resistance effects: Can delay flowering, helping crops avoid early-spring frost damage. This reduces flower and fruit drop caused by cold weather during the flowering stage and enhances the crop's adaptability to adverse environmental conditions.

Chlormequat Chloride (CCC) / Paclobutrazol (Paclo)
Growth-promoting effects: Inhibits excessive vegetative growth (leggy stems) and shortens internodes, resulting in sturdier, thicker stems. It facilitates the translocation of nutrients toward the fruit, thereby increasing fruit-set rates and the thousand-grain weight.
Stress-resistance effects: Increases cell wall thickness, significantly improving lodging resistance (resistance to falling over). It also enhances tolerance to drought and cold while reducing water loss, making these agents well-suited for improving stress resilience in field crops such as wheat and rice.