The Regulatory Roles of Phytohormones in the Wheat Grain-Filling Process

In cereal crops such as wheat, the grain-filling process is governed by various endogenous factors, with phytohormones playing a pivotal role in grain development. Key factors influencing grain weight include the efficient translocation of photosynthetic carbohydrates to developing grains, sink strength, and the sustained continuation of current photosynthesis. Following anthesis, pre-anthesis reserves and current photosynthates are mobilized to the grains to support their development. Auxin, cytokinin, and abscisic acid are the primary phytohormones involved in facilitating the translocation of photosynthates to developing grains. The rate and duration of grain filling, spanning from anthesis to maturity, are critical determinants of wheat grain growth. This review focuses on elucidating the role of these three phytohormones, i.e., auxin, cytokinin, and abscisic acid, in the grain-filling process. It provides a concise critique of their application in enhancing grain filling, examines the mechanisms by which these growth regulators influence grain weight, and offers recommendations for future research.