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Feminizing your crop - In Depth

Discussion in 'Advanced Growing Techniques' started by stewie21, Apr 18, 2009.

  1. Feminizing: All You Ever Wanted to Know About Sexual Expression, and changing it

    [This is from rexresearch.com, an excellent site for anything to do with growing cannabis. I bolded the stuff i found more applicable. Feel free to +rep if you learn something, i definitely did]

    The sexual expression of cannabis is determined by its genetic makeup, and by its metabolic temper, which is regulated by the male enzyme andrase and the female enzyme gynase. Environmental conditions (light, nutrients, soil and water) may suppress the formation of the dominant enzyme, and allow the opposite sex to express itself partially (hermaphroditism) or completely (sex reversal). (71, 72)

    [About this next paragraph: I thought that normal levels of N with lowered levels of K were ideal for producing fems in early veg...]

    Nitrogen fertilizers masculinize the phenotype by stimulating the formation of male flowers. The proportion, number and degree of monoecious plants increases with increasing N, and the total N content is always higher in monoecious individuals than it is in females. (79)

    Treatment of hempseed with ethylene gas will increase the resulting number of female plants by about 50%. Ethylene is produced by certain plants (i.e., bananas, cucumbers and melons), and these can be used to treat hempseed in a simple manner. About two weeks before you plan to sprout the seeds, place them in a paper bag or envelope and put that in a plastic bag with the peels of a ripening banana or cucumber. Replace the peels after a couple of days, and change the bags to prevent mold.

    Hempseed can be feminized while they are forming on the plant. Fruit peels are spread around the area for two weeks before the plants enter the flowering phase. Remove the skins when the plants begin to flower. Otherwise, treatment with Etephon will accomplish the same effect.

    When hempseed is treated with the female hormone estrogen, percentage of females that are produced will increase by about 10%. Dissolve a birth control pill in water and soak the seeds overnight in the solution. After the initial soaking, continue to treat the seeds by sprouting them on a paper towel soaked in the solution. (80)

    A.I. Zhatov tested the effects of ethrel on hemp:
    "Treatment of hemp plants with an aqueous solution of ethrel changed the ratio of male to female flowers. The greatest effect was observed when plants were treated during flowering of male flowers." (81)

    Electricity also can change the sexual expression of cannabis; B.R. Lazarenko and I.B. Gorbatovskaya reported:

    "Under the influence of the electrical current, the numerical proportions between hemp plants of different sexes was changed by comparison with the control to give an increase of female plants by 20-25%... The characteristics acquired by the plants in electrically treated soils are transmitted by inheritance to the third generation..." [emphasis added] (82)

    Photoperiodism is a most useful tool with which to control the sexual expression of cannabis. For example, J. Limberk made a careful study of lighttime on the sexual index of hemp, and reported thus:
    "Male plants usually flowered earlier than female. Female plants flowered only when the period of daylight was shorter than 14 hours; male plants flowered even when the day was longer than 14 hours. Reduction of light intensity in the first stages of plant development lead to increases of female plants by 4.3%. Intersexual plants (22-30% of the total) were present in conditions of 11-13 hours light per day. Grafting of plants did not change sex."

    The probable future sex of a pre-floral hemp plant can be guessed at by calculating the Leaf-Mass Index (LMI): Count the points (3, 5, 7) on 3 leaves in the center of a cluster. Divide that number by 3 to determine the average number of points. Repeat the process several times, and figure that average also. Multiply the two averages to determine the LMI. A high LMI indicates that the plant will be female.

    The phyllotaxy changes to alternate just before the onset of flowering. Then the sex of the plant can be determined by making a close examination of the upper nodes of the main stem. The onset of flowering is indicated by the appearance of undifferentiated primordial buds behind the stipules at the nodes of the petioles (along the stem at the base of branches). Within a few days they differentiate. The male pistils are flat or knobby with a curved shape and 5 open petals about 5 mm. long; they have a single tiny stalk. Overlapping vegetation often disguises their appearance.

    The female develops pairs of flowers surrounded by pointed bracts of protective leaves that will enclose the seed. The female stigma usually appear as 2 fuzzy white hairs forming a "V" that protrudes from a bract. Resinous hairs (glandular trichromes) cover the calyx (2-6 mm long).

    Gibberellin will inhibit the formation of flowers on cannabis, but sometimes it will otherwise cause the growth of fertile female flowers on genetically male plants. Silver nitrate or cobalt chloride causes masculinization of flowers of female hemp, possibly due to blockage of ethylene synthesis. High levels of N salts --- and long photoperiods --- have a masculinizing effect on hemp.(74-76)

    "Dioecious hemp plants were grown to an age of 20 days in a day-length of 21-22 hours, then given an inductive treatment of ten 8-hour days to initiate flowering. After return to long days and during the period of differentiation of flower buds, a total of 0.5 gr lanolin paste containing 0.5% NapthaleneAcetic Acid (NAA) was applied to leaves at the 3rd and 4th nodes. In genetically male plants, female plants were subsequently formed in sites which would normally be occupied by males, a result which appears to be regulated by the level of native auxin in the vicinity of meristems during the period of differentiation of flower primordia. Secondary effect of auxin treatment were evident in an over-all reduction in intensity of heteroblastic development, the trend towards a reduction of leaf lobing and serration which normally accompanies plants passing through a period of flowering than in untreated controls." (78)
  2. Goood Post!

    But now im torn,
    If I scoop a few of my wifes birth control pills
    I might have another "little accident" running around!
    But I could also have a ton of some what feminized seeds!
  3. has any tried the method where you put the seeds in a bag with bananas or cucumbers. it doesnt seem like that would work but i don't know.

    would it be more likely to work when you start the paper towel germination, or is that what they meant?
  4. i herd the birth control pill method causes hermies
  5. Now that was a great post. I have always wondered how seed companies 'feminized' seeds. But isn't the gender of any living organism determined in it's DNA coding? I always believed that altering DNA caused reversion mutations? Or does the seed itself have an undefined gender to begin with? I can grasp the concept of creating a hermaphrodite, it's the same reason why 'women who are pregnant or are planning to become pregnant should not touch certain medications' because certain anti-androgenic hormones can actually be absorbed through the skin leaving a fetus' gender incomplete and/or mutated. But they can't actually change gender as much as they can hinder it's completion.
    Wow, now I'm more intrigued than ever. Thanks for the brain food. Now I have something to research in my off time.
  6. #6 breedtheweed, Apr 23, 2009
    Last edited by a moderator: Apr 23, 2009
    incredible info there.Thanks for such a great read.I have tried the silver nitrate to fertilize a great female I have just to save the line.I have got 20 seed put back from her now.But I will be using the ethlene method to heart from now on too having been in the nursery trade most of my life,ethylene gas and its affects are well known methods of inducing flowering in many plants,But I did not relize it could alter the seedlings sex.
  7. lol do it for the seeds bro!

    A bunch of us on GC and elsewhere use this method and end up getting 70-80% females, but you can get ratios this high with just enviromental factors like more N, less K, ambient temps around 70deg, humidity around 70%, light cycles at or below 18/6, and keeping the roots warm.

    From what I've read, the sex is genetically determined to be 20% true males, 20% true females, and 60% that can go either way or hermie. Ideal conditions can turn the 60% into females, but the 20% males are always that.

    Seed companies have a much more complicated process to feminize seeds to 99%, involving a couple years of breeding, stressing, and forcing male flowers on the strongest females.
  8. thank you for the answer, and all the great info,
    but someone asked if the birth control pill method caused hermies, is this true?
  9. I'm not sure. I know that the estrogen has a slight feminizing effect.
  10. Interesting read, I found this and figured we could add it in here

    Grasscity » How to grow marijuana?
  11. #11 stewie21, Apr 23, 2009
    Last edited by a moderator: Apr 24, 2009
    Interrupting the night cycle with an hour of light increases the amount of hermies considerably. It's a way to stress plants to show hermie genetics, so it is used primarily for breeding.

    Unless you want to destroy your sensimilla crop with seeds, don't interrupt the light cycle.
  12. amazing, i thank you so very much as i have always searched and wondered how to do so. Thanks so much!
  13. #13 Liz_Lemon, May 5, 2009
    Last edited by a moderator: May 5, 2009
    Great post, I was searching "estrogen" to see if I should pop a birth control pill in when I soak my seeds.
    Ya know, the more I try to read and learn, the more questions I end up having.
    Fuck stressing the plants, I'm a stressed grower.
    I need to just relax and enjoy growing my plants...

    Oh and dude with the wife on the pill, EVERY chick on the pill has an extra pack or two, it's the only way to adjust your cycle to line up with your vacations and stuff.

    Edit: This guy...
  14. Birth control is not estrogen, but a relative or mimic. Usually, progesterone. It would be advisable to use a plant estrogen that will not result in some nice lady missing her nobabies pill. By the way, birth control may be a problem for many women later in life.

    The sex of the plant is determined by diffuse genetic markers (probably spread across the genome) not x and y chromosomes. This is why there is so much sexshifting with the Cannabis.

    Doesnt a good 100-300 ppm GA3 spray give you localized (to the area of applicaiton) pollen production? You can get GA3 cheap from supergrow.biz

    I dont believe it is possible to get 100% true fems, just 100% fem expression with a higher then normal percentage of true fems. This is because a true fem cant produce pollen and cannot be selfed. Fem seeds seem a waste to me, but if people want em. This is becasue Im pretty sure one could get consistantly 75% fem expressing plants from normal seed with a proper production schedule which includes ethylene and auxin treatments.

    Also, if one wants to weed out fem expressing plants with male markers one might try giving male treatments to the seedlings and keeping the resulting female plants. They will most likely be heavy or true fems. I think BAP works good cause it tends to produce healthy, bushy plants but mostly male.
  15. Does anyone have a source for Ethephon Growth Regulator?? I have found much info on the web but none for U.S. sources. Apparently this stuff is 'dangerous' and controlled by EPA. It also works to feminize many commercial crops. Easy to find in China and Australia. Not so much in U.S.! Thanks:smoke:
  16. Good post Stewie21 and I came across Robert A Nortons Hemp Husbandry only yesterday as I was looking to find the genetic mechanism by which 2 Exodus Cheese clones of mine grew out as perfect males (no, not herms ) when they were put into flower and reading his stuff has given me a clue:

    The sexual expression of cannabis is determined by its genetic makeup, and by its metabolic temper, which is regulated by the male enzyme andrase and the female enzyme gynase. Environmental conditions (light, nutrients, soil and water) may suppress the formation of the dominant enzyme, and allow the opposite sex to express itself partially (hermaphroditism) or completely (sex reversal). (71, 72)

    " or completely"

    I'm currently trying to source andrase and gynase or a chemical that mimics their action.

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