GA3 (gibberellin) and GA4+7 (a mixture of gibberellin A4 and A7) are the two most widely used gibberellins in agricultural production. Although both are plant growth regulators, they differ significantly in their core efficacy and applicable scenarios. Based on current research, I will explain their differences in detail from three dimensions: mechanism of action, differentiated effects on fruit quality, and specific applications on major crops.
Mechanism of Action: Differences Starting at the Molecular Level
The most fundamental difference between the two stems from their different molecular mechanisms of inducing specific physiological responses in plants.
GA3: A Broad-Spectrum and Highly Effective “Universal Key”
GA3 is the oldest and most technologically mature gibberellin. Like a “universal key,” it can broadly activate various physiological processes in plants, showing significant effects in inducing seedless grape production, elongating bunches, promoting cell division, and conventional fruit retention. For example, using 50 mg/L of GA3 on Red Globe grapes increased the average single-berry weight by 18.1% and the soluble solids content by 7.5% compared to the control group.
GA4+7: A “Smart Key” for Precise Regulation
GA4+7 acts more like a “smart key,” precisely activating specific signaling pathways. Recent molecular research shows that GA4+7 specifically regulates the PbDELLA-PbMYB56-PbCYP78A6 gene module, inducing ovule development into “false embryos” without pollination, thereby promoting ovary enlargement and achieving parthenocarpy (seedless fruit). This explains why GA4+7 is more effective in inducing the development of specific fruits (such as pears and mangoes).
Differentiated Impact on Fruit Quality
This is the most crucial difference between the two in production, directly determining the market value and flavor of the fruit.
| Comparison Dimensions | Effects of GA3 | Effects of GA4+7 |
| Fruit Size and Shape | Strongly promotes fruit enlargement: Significantly increases berry weight, as seen in grapes where it has a clear effect on yield increase. Causes fruits to tend to become longer. | Promotes longitudinal elongation and overall size: Studies on mangoes show that GA4+7 is superior to GA3 in promoting longitudinal elongation and overall size of the fruit. Causes fruits to tend to become rounder. |
| Internal Quality (Sugar and Acid) | Primarily increases acidity: Experiments on pears have confirmed that GA3 treatment significantly increases the titratable acid content (i.e., acidity) of the fruit, but has little effect on soluble sugar content. | Significantly improves sugar-acid ratio: GA4+7 significantly increases the soluble sugar content of the fruit while tending to decrease titratable acid, thereby improving the taste and flavor of the fruit. |
| Fruit Firmness and Coloring | Treatment of sour cherries shows that GA3 has no significant effect on improving fruit firmness. In rice, it is used to improve seed vigor. | It can increase fruit firmness (such as in sour cherries), and when combined with other regulators, it can enhance the color and aroma content of apples. |
Specific Applications in Major Crops
Understanding the essential differences between the two allows us to better understand their different applications in the field.
| Crops | Core Applications of GA3 | Core Applications of GA4+7 |
| Grapes | Seedlessness induction, flower and fruit retention, bunch elongation, and promotion of fruit enlargement. This is a classic application area for GA3, with mature technology and high cost-effectiveness. | It can also be used as an auxiliary or alternative choice to control fruit shape (making the fruit more rounded) and improve the internal quality of the fruit. |
| Pears | Significantly improves fruit set rate, promotes fruit enlargement and earlier ripening, but increases acidity, affecting flavor. | GA4+7 improves fruit set rate, increases fruit sugar content, and reduces acidity, making it an ideal choice for producing high-quality pears. |
| Mangoes | Promotes the growth of embryoless fruits, reduces fruit drop, and promotes fruit elongation. | Superior to GA3 in promoting longitudinal fruit elongation and overall fruit enlargement, especially suitable for targeted supplementation of endogenous hormones needed for embryoless fruit development. |
| Stone fruits (cherries, etc.) | Significantly increases fruit size, delays leaf senescence, and improves the frost resistance of flower buds in spring. | Increases fruit firmness and delays leaf senescence. |
| Pome fruits (apples, etc.) | Relatively little research has been conducted. | Improves fruit appearance and internal quality, and when combined with other regulators, significantly increases the content of aroma compounds. |
| Others (guava, etc.) | Reduces seed number and increases fruit set rate. | Also reduces seed number, but high concentrations may cause phytotoxicity. |
Core Summary and Selection Recommendations
In actual production, the choice of which gibberellin to use fundamentally depends on your planting goals:
1.If your goal is to achieve efficient seedless grape cultivation, perform routine flower and fruit retention operations, or quickly elongate the fruit bunches: GA3 is the reliable and cost-effective first choice, proven through long-term practice.
2.If your goal is to produce high-quality fruit, hoping to increase fruit sugar content, improve flavor, optimize fruit shape (e.g., make mangoes longer, pears rounder), or to perform precise regulation for specific fruit trees such as pears and mangoes: GA4+7 is a better choice. It can help you produce fruit with better flavor and appearance, establishing competitiveness in the high-end market.
3.The two are not entirely mutually exclusive: in some cases, they can be used in combination to combine the powerful growth-promoting effect of GA3 with the quality-improving effect of GA4+7. For example, studies on pears have used a mixture of GA3 and GA4+7 with good results.