Effect of 14-Hydroxylated Brassinosteroids Growth Regulator on Growth and Yield of Rapeseed

As a new Plant growth regulator, 14-hydroxylated brassinosteroids (14-HBR) increase biological activity by 50% than the traditional Brassicin sterols, while the relation effect of 14-HBR on rapeseed growth, yield and seed coating pesticide were not clear.

In this study, 14-HBR regulator and pesticide are used to treat the seeds in mid-duration winter rapeseed variety (Yangguang 2009) and early-duration variety (Yangguang 131), investigated germination, seedling growth, insect resistance, and yield, to reveal the interaction effects of environment, variety genotype and 14-HBR.

0.0075 and 0.015 mg·L^-1 14-HBR treated seed increased significantly germination potential in medium duration rapeseed, but decreased germination potential and germination rate significantly as mixed with pesticide. 14-HBR treated seed had no significant effect on germination rate and germination potential in short duration rapeseed. The 14-HBR showed better biological activity in seedling growth and yield than that of Brassinolide, 0.0075 and 0.015 mg·L^-1Brassinolide increased by an average of 5.19% and 8.15%, 0.0075 and 0.015 mg·L^-1 14-HBR increased by an average of 11.98% and 5.50%, respectively. 14-HBR mixed with seed pesticide of Clothianidin and Thiamethoxam, also increased seedlings weight and yield. The yield of Thiamethoxam and Clothianidin seed treatments increased by 4.7% and 4.6% independently. The yield of mixed with 0.0075 and 0.015 mg·L^-1 14-HBR to Clothianidin increased 6.8% and 3.3%, mixed to Thiamethoxam increased by 3.5% and 8.2%, respectively. 14-HBR did not affect insecticidal activity of Thiamethoxam and Clothianidin to peach bud nymphs and phyllotreta striolata fabricius.

The study revealed seed treatment with 14-HBR regulator has a positive effect on early growth of rapeseed and increased yield of rapeseed significantly, interacted with planting environment, pesticide type and varieties genotype as traditional regulators, it is necessary to optimize seed treatment technology of 14-HBR regulator to obtain higher harvest yield.