Objective Effects of application timing of ethephon (ETH) and/or jasmonic acid (JA) in regulating the growth, yield, and quality of sugar beets were studied.

Method A field experiment was conducted in Shihezi, Xinjian in 2025 on sugar beet KWS7748 . The plants were foliar-sprayed with water as control (CK), ETH at early, rapid leaf growth stage (T1), JA at mid-late, root bulking stage (T2), ETH and JA at early stage (T3) or ETH and JA at mid-late stage (T4). Agronomic traits, photosynthetic characteristics, antioxidant enzyme activities, and beet yield and quality indicators were monitored throughout the plant growth periods.

Result T1 significantly increased the beet yield over CK to 148.05 t·hm⁻². However, the sugar content in the beets was the lowest among the plants under the various treatments. In contrast, T2 also significantly elevated the yield but maintained a constant sugar content. Between T3 and T4, T3 produced plants with greater leaf area index (LAI), total chlorophyll content at late stage, and antioxidant activity, resulting in higher beet yield of 143.16 t·hm⁻² with the highest sugar content of 11.51% and crop yield of 16.46 t·hm⁻². The principal component analysis indicated that T3 simultaneously optimized the cultivation on source-sink relationship, stress resistance, yield as well as beet quality.

Conclusion The foliar application of 900 g·hm⁻² ethephon with 225 g·hm⁻² jasmonic acid at the rapid leaf growth and root bulking stages was effective in increasing the yield and sugar content in the beets.