Forming Female Flowers on Male Cannabis Plants

Forming Female Flowers on Male Cannabis Plants

Research Article
Moon, Y.-H., Lee, Y. J., Koo, S. C., Hur, M., Huh, Y. C., Chang, J.-K., & Park, W. T. (2020). Effect of Timing of Ethephon Treatment on the Formation of Female Flowers and Seeds from Male Plant of Hemp (Cannabis sativa L.). 한국자원식물학회지, 33(6), 682–688.
https://doi.org/10.7732/KJPR.2020.33....

Self Fertilizing
While self fertilizing a plant can help retain certain genetic traits this can be quite a challenge with dioecious plants such as cannabis that produces distinctive male and female plants.
Since each plant only produces one type of flower this creates an inherent problem with self fertilizing.
Some growers may just decide to clone the plant, but this does not allow for the production of seeds which may be desired.



Determine Male Plant Primordia
Determine when primordia (early flower development) formation occurs
Male primordia can be identified by their curved claw shape which will be followed by the differentiation of round pointed flower buds.
At the time of primordia formation, primordia were formed between stipule and petiole under shoot tip.
As time goes on, leaves became smaller, decreased and more flowers were formed.



Plant Treatment
7-14 days after the primordia formation plants male plants should be treated with 500 ㎎ L-1 of ethephon to induce female flower formation.
Dilution rates provided at end

Male plants at the time of ethephon treatment
A: Male plants at the time of ethephon treatment after male primordia formation
B: 7 days later
C: 14 Days later



Female Flowers of Male Plants…
Have 5 stigmas in contrast to the dual stigma of female plants.
Male plant seeds were lighter and smaller than those from female plants.
Although the germination rate was lower (compared to normal seeds from female plants) the seeds from male plants germinated to grow seedlings.



Ethephon Treatment Conclusion
Treating ethephon to male plants at soon after primordia formation will be good strategy in breeding program to breed inbred lines of hemp by self-fertilization.



Calculating 500mg per Liter of Ethephon Part 1
Note: Goal is 500mg/L = 0.05%
21.7% Ethephon
Same as 217,000 mg per liter

C1 is the concentration of the stock solution.
V1 is the volume to be removed (i.e., aliquoted) from the concentrated stock solution.
C2 is the final concentration of the diluted solution.
V2 is the final volume of the diluted solution. This is the volume that results after V1 from the stock solution has been diluted with diluent to achieve a total diluted volume of V2.
An alternative and commonly-used notation for this equation is M1V1 = M2V2, where M is used in place of C.

Calculating 500mg per Liter of Ethephon Part 2
Note: Goal is 500mg/L = 0.05%
21.7% Ethephon
Same as 217,000 mg per liter

Calculating 500mg per Liter of Ethephon Part 3
Note: 0.002304 L = 2.304 mL
Take L and divide by 1000 to get mL

Aliquot exactly 2.304 mL of the 217000 mg/L stock solution and dilute with water to a final volume of exactly 1 L.

This will yield 1 L of a diluted solution with a final solute concentration of 500 mg/L.


Note that the final volume refers to the total solution volume, which is the combined volume of the stock solution and the volume of water used for dilution.




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