Effects of exogenous 2,4-epibrassinolide and its inhibitors on the seed setting and yield of Tartary buckwheat

The aim of this study was to evaluate the effects of exogenous 2,4-epibrassinolide (EBR) on the yield of Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.). A 2-year field experiment was conducted on Tartary buckwheat (cv. Jinqiao 2) with different concentrations (0, 0.1, 0.5, 1.0, and 2.0 mg/L) of EBR and brassinolide (BRZ, inhibitor of brassinolide synthesis). The seed setting rate, agronomic traits, and yield initially increased and then decreased with an increase in the EBR application rate. The seed setting rate, agronomic traits, and yield decreased gradually with an increase in BRZ concentration, and yield was the lowest at 2.0 mg/L. The appropriate application of exogenous EBR could promote the increase of Tartary buckwheat yield. Compared with 0 mg/L (control), the 0.1, 0.5, and 1.0 mg/L treatments increased yield by 13.53, 32.73, and 7.08%, respectively, while the high-concentration treatment (2.0 mg/L) decreased by 4.13%. In conclusion, the appropriate concentration of EBR treatment (0.5 mg/L) delayed the senescence of Tartary buckwheat by increasing its root activity and the activity of antioxidant enzymes in leaves. Simultaneously, it increased the chlorophyll content of Tartary buckwheat leaves, enhanced photosynthesis, increased nonstructural carbohydrate content, and augmented the "source," increasing the seed setting rate and yield of Tartary buckwheat. This concentration is recommended for use in the production of Tartary buckwheat.