Role of 24‐Epibrassinolide in Wheat Production: Physiological Effects and Uptake

Abstract Brassinosteroids are plant steroid hormones important for plant growth and development. They include more then 70 compounds. Their physiological effect and possibilities of practical use are still being investigated. In this study, we evaluated the effects of exogenously applied 24‐epibrassinolide, one of the brassinosteroids, on the grain yield and grain chemical composition (carbohydrates, proteins, fats and minerals) of wheat. Moreover, we analysed the presence of brassinosteroids in newly formed wheat grains after exogenous plant treatment with 24‐epibrassinolide. Experiments were performed in a vegetation hall (plants cultivated in pots) and in the field. The tested regulator was applied via 48 h seed soaking (1 mg·dm −3 ) or spraying plants at the heading stage (0.25 mg·dm −3 ). 24‐epibrassinolide increased grain yield in plants growing in the field (by about 20 %), but not in plants cultivated in vegetation hall. Grain chemical composition was altered by 24‐epibrassinolide in wheat growing in the vegetation hall; the content of soluble sugars was higher while that of total fats and calcium was lowered, whereas the starch and soluble protein content was not affected. The effect of the hormone was in these cases dependent on the method of its application. As for plants cultivated in the field, the hormone impact on the amount of carbohydrates, proteins, fats and minerals contained in the grains was rather negligible. In wheat grains, the presence of brassinolide, castasterone and 24‐epicastasterone was found. 24‐Epibrassinolide applied exogenously to plants was not accumulated in newly formed grains. Additionally, significance of ethanol as a hormone solvent is discussed.