Determination of Brassinolide on Radish Hypocotyl Elongation Activity



At present, there are many kinds of brassinolides, such as 24-epibrassinolide, 28-homobrassinolide, 28-epihomobrassinolide, 14-hydroxybrassinolide, etc. But their activities are quite different. How to determine the activity of brassinolide? There are 6 common methods for measuring the bioactivity of brassinolide, such as wheat coleoptile unfolding test, bean second internode elongation test, cucumber hypocotyl elongation test, radish hypocotyl elongation test, etc.

Radish hypocotyl elongation bioassay method is short cycle, small footprint and relatively simple operation. In order to clarify the activity difference between 24-epibrassinolide and competitive products, radish seeds were sown on vermiculite for 4-6 days, and taking out the seedlings. The hypocotyl length was selected to be 2-3cm, and the segments were soaked in the culture dish solution (10ml), cultured at room temperature and light for 24-48h, and the hypocotyl length was investigated.              

Brassinolide Activity test on Radish Hypocotyl Elongation

Test Site: Henan Crop Chemical Control Engineering Technology Center, Zhengzhou 

Test time: October 23, 2020, application Date: October 26, 2020

Test variety: Weifang radish 

Test Methods: The hypocotyls were cut 2.5cm and immersed in different types and doses of brassinolide. The length was observed and measured after three days.

Experimental result: After 3 days of observation 0.1-1mg/L brassinolide, the average length of radish hypocotyl was 4.7-4.8cm, which was 1.7-1.8cm higher than that of 0 days; the average length of sterol and water control was 3.4-3.5cm, increased by 0.4-0.5cm. The length of 24-epibrassine was 1.2-1.4cm longer than that of control and sterol treated radish hypocotyl, and the activity was significantly better than that of sterol and control.


0D radish hypocotyl dissection

1mg/L effect in 3 days                                              


                  CK                                      zs-chem product                     other product

1mg/L effect in 3 days


               CK                                   zs-chem product                          other product

Effect of each treatment at a dose of 0.1mg/L for 3 days

Table 1 Changes of hypocotyl length of radish under different treatments in 3 days

hypocotyl length (cm)


24-epibrassinolide 0.1mg/L

Epocholeone 0.1mg/L

24-epibrassinolide 1mg/L

Epocholeone 1mg/L


3.53±0.05 b

4.80±0.12 a

3.47±0.08 b

4.68±0.20 a

3.38±0.08 b

In this concentration range, the activity of Epocholeone was not significantly different from that of water control, while 24-epibrassinolide activity was very high, and hypocotyl elongation was significantly greater than that of water control and Epocholeone, The average length is 1.2cm longer than Epocholeone. It can be seen that the activity of different brassinolide is directly different. The common 24-epibrassinolide has the characteristics of low dosage, high activity, obvious effect, and high safety. It is widely used in many crops at all over the world.