S-abscisic Acid can significantly enhance wheat's resistance to drought, disease, and cold, while also promoting secondary root development and increasing the number of effective tillers.
Acting as a plant "stress-resistance inducer," this substance rapidly activates the expression of endogenous stress-resistance genes when wheat encounters drought, low temperatures, or disease stress. Under drought conditions, abscisic acid induces the rapid closure of stomata to reduce water transpiration; simultaneously, it upregulates the expression of genes such as P5CS to promote proline accumulation and maintain cellular osmotic balance. Studies have shown that exogenous application of S-abscisic Acid enables wheat to maintain a higher leaf water potential under drought stress, boosting photosynthetic efficiency by over 26.9%.
Foliar application of 50–100 ppm S-abscisic Acid prior to exposure to low-temperature stress can induce the synthesis of cold-resistance proteins and enhance membrane lipid stability, thereby significantly reducing the rates of chlorosis and seedling mortality caused by freezing damage. Furthermore, by activating the signaling pathways of salicylic acid (SA) and jasmonic acid (JA), abscisic acid bolsters wheat's systemic immunity, enhancing its defensive capabilities against diseases such as blight and root rot.
In terms of growth regulation, low concentrations of abscisic acid (1–2 mg·kg⁻¹) can promote the formation of secondary roots in wheat, thereby enhancing its capacity for water and nutrient uptake. Foliar application of 1–2 ppm S-abscisic Acid during the green-up stage effectively promotes tiller conversion, increases the number of effective tillers, and optimizes the plant population structure, ultimately leading to higher ear-formation rates and increased yields.
In practical application, it is recommended to foliar spray 1–2 ppm S-abscisic Acid on winter wheat either before the green-up stage or during the early tillering stage, applying it twice at 7-day intervals; alternatively, a preemptive treatment with 50–100 ppm can be applied prior to the arrival of a cold wave to enhance stress resistance.
