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CROSS-HYBRIDIZATION OF DISTINCT HOMOZYGOUS CANNABIS PLANTS TO PRODUCE CONSISTENT EARLY FLOWERING SEEDS
United States Patent Application 20190297821
Abstract:
A method for developing seeds for consistent early flowering short-day Cannabis plants, the method including crossbreeding a short-day Cannabis plant with a day-neutral Cannabis plant, and collecting the seeds produced through crossbreeding.
Inventors:
Crawford, Seth S. (Albany, OR, US)
Crawford, Eric B. (Corvallis, OR, US)
Application Number:
16/364715
Publication Date:
10/03/2019
Filing Date:
03/26/2019
Claims:
What is claimed is:
1. A method of developing seeds for consistent early flowering short-day Cannabis plants, the method comprising: crossbreeding a short-day Cannabis plant with a day-neutral Cannabis plant; and collecting the seeds produced through crossbreeding.
2. The method as claimed in of claim 1, wherein the short-day Cannabis plant is Cannabis sativa.
3. The method as claimed in claim 1, wherein the day-neutral Cannabis plant is Cannabis ruderalis.
4. The method as claimed in claim 1, further comprising selecting the short-day Cannabis plant based on at least one of resin levels, terpine profile, cannabinoid levels, and structure.
5. The method as claimed in claim 1, further comprising selecting the day-neutral Cannabis plant based on at least one of resin levels, terpine profile, cannabinoid levels, and structure.
6. The method as claimed in claim 1, further comprising inbreeding the short-day Cannabis plant prior to the crossbreeding.
7. The method as claimed in claim 6, wherein inbreeding includes: inducing staminate flowers on a pistillate plant; and pollinating pistillate flowers on the pistillate plant with pollen from the induced staminate flowers.
8. The method as claimed in claim 6, further comprising selecting the short-day Cannabis plant for inbreeding based on at least one of resin levels, terpine profile, cannabinoid levels, and structure.
9. The method as claimed in claim 6, wherein inbreeding the short-day Cannabis plant includes homogenizing the initial Cannabis plant for at least 3 generations.
10. The method as claimed in claim 1, further comprising inbreeding the day-neutral Cannabis plant prior to the crossbreeding.
11. The method as claimed in claim 10, wherein inbreeding includes: inducing staminate flowers on a pistillate plant; and pollinating pistillate flowers on the pistillate plant with pollen from the induced staminate flowers.
12. The method as claimed in claim 10, further comprising selecting the day-neutral Cannabis plant for inbreeding based on at least one of resin levels, terpine profile, cannabinoid levels, and structure.
13. The method as claimed in claim 10, wherein inbreeding the day-neutral Cannabis plant includes homogenizing the initial Cannabis plant for at least 3 generations.
14. The method as claimed in claim 1, wherein crossbreeding includes: inducing staminate flowers on a pistillate plant; and pollinating a second pistillate plant with pollen from the induced staminate flowers.
15. A Cannabis seed, developed from the crossbreeding of a short-day and a day-neutral Cannabis plant, comprising: early flowering characteristics, wherein the Cannabis plant grown from the seed will flower when exposed to a critical photoperiod that includes about 540 minutes of uninterrupted darkness.
16. The Cannabis seed as claimed in claim 15, wherein the short-day Cannabis plant is Cannabis sativa.
17. The Cannabis seed as claimed in claim 15, wherein the day-neutral Cannabis plant is Cannabis ruderalis.
18. A Cannabis seed obtained by crossing: a first Cannabis plant that is transformed preferentially to have a first homozygosity level and to express short-day characteristics, whereby flowering depends on a change in photoperiod; and a second Cannabis plant that is transformed preferentially to have a second homozygosity level and to express day-neutral characteristics, whereby flowering does not depend on a change in photoperiod.
19. The Cannabis seed as claimed in claim 18, wherein the first and second homozygosity levels are measured by genetic testing.
20. A method of producing an early flowering Cannabis plant, the method comprising: crossing a day-neutral Cannabis ruderalis plant with a short-day Cannabis sativa plant; recovering the resultant F1 hybrid Cannabis seed; planting the resultant F1 hybrid Cannabis seed and growing into plants; and selecting resultant Cannabis plant from the planting having a desired trait.
Description:
CROSS REFERENCE TO RELATED APPLICATION
This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/649,424 filed Mar. 28, 2018, which is incorporated herein by reference in its entirety.
TECHNICAL FIELD
This disclosure is directed to the production of seeds for early flowering Cannabis plants, and, more particularly, to a method of crossbreeding distinct homogenous species of photosensitive short-day Cannabis plants with day-neutral Cannabis plants to achieve a first generation of consistent early flowering Cannabis plants for optimizing field use and harvest yields.
BACKGROUND
Cannabis is a genus of plants useful in the industrial or artisanal production of oil, fiber, food, fragrance, and medicine. The various parts of Cannabis plants may be used in a near infinite number of products, such as fiber, oils, and medicines, for example.
As the number of indoor Cannabis growing operations expands, increasing amounts of energy and electricity are required for the lighting needs of the plants. With further legalization, it is expected that prices for Cannabis products will lower, making it harder for indoor operations to afford the overhead for their power costs and further incentivizing the switch to natural, outdoor growing. However, in contrast to the continuously controlled lighting cycles of indoor operations, outdoor growing is subject to the seasonal timing of natural sunlight cycles. Typically, sun-grown Cannabis is planted in spring, flowers when nighttime exceeds about 10-12 hours, and is ready to harvest in late autumn. Additionally, there has been significant variation in flower induction timing across and within Cannabis cultivars.
Accordingly, there exists a need to consistently shorten the time to harvest for sun-grown Cannabis crops while maintaining any desired traits and yield.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of example breeding results for day-neutral and short-day Cannabis plants, in accordance with the present disclosure.
DETAILED DESCRIPTION
Disclosed herein are systems and methods for producing complex hybrids of Cannabis plants that begin flowering when exposed to a light cycle including about 540 minutes (9 hours) of uninterrupted darkness. As explained in detail below, it has been found that crossing homozygous varieties of short-day Cannabis sativa with homozygous varieties of day-neutral Cannabis ruderalis results in consistent early flowering short-day Cannabis hybrid progenies.
This type of crossbreeding of Cannabis plants has not been found to work with varieties of mulberry and hops plants, which are the closest relatives to Cannabis plants, found within the Moraceae and Cannabaceae families.
Plant species in the genus, Cannabis, are annual plants that are wind-pollinated to produce seeds that germinate the following year. Cannabis plants are dicotyledons that bear fruit in the form of achenes, which consist of one seed protected by two cotyledons or bracts (i.e., embryonic leaves) as well as energy rich nutritional proteins with all the essential amino acids.
Cannabis plant species are dioecious, meaning that staminate plants with a male sex chromosome (i.e., XY) have male flowers containing microgametophytes within the pollen, and pistillate plants with only female sex chromosomes (i.e., XX) have female flowers containing megagametophytes within the ovules. Hermaphroditic plants and flowers are also possible in monoecious phenotypes, although they are generally sterile. Morphological differences for visually distinguishing between male and female plants develop during the reproductive stage.
The diurnal light cycle and/or exposure to low levels of carbon monoxide may change the gender expression of a plant. Feminized seeds may also be produced by treating isolated portions of female plants with hormones or silver thiosulphate to induce pollen formation.
The life cycle of Cannabis plants includes germination/emergence, vegetative growth, reproductive stages, in which flowers and seeds are formed, and finally, senescence. The time for maturation may vary from about 2 to 10 months, but naturally, the time from seed to harvest is about 8 months. However, artificial indoor growing operations can speed the life cycle of Cannabis plants to just 90 days by boosting light exposure and tightly controlling the timing of the required photoperiods (discussed in detail below).
Cannabis seeds mostly lack dormancy mechanisms and germinate without requiring any pre-treating or winterizing. Weights range from about 2 to 70 grams per 1,000 seeds. When placed in viable growth conditions, Cannabis seeds germinate in about 1-19 days.
The stages of vegetative growth include time as a juvenile (basic vegetative phase) and a photosensitive phase, lasting until the development of flowers. Vegetative growth may last for about 2-20 weeks, during which growth increases in response to temperature and increasing light exposure, and plants may be grown to their desired size. After the juvenile stage of about 1-8 weeks, plants require at least 12 hours of light before flowering may begin about 1-12 weeks later. Exposing the plants in the photosensitive phase to a critical photoperiod (e.g., about 14-16 hours of light) begins flower development. In general, about 18-20 hours of light per day during the vegetative growth stage has been shown to produce the highest yields for some Cannabis plant varieties. Interrupting the continuity of just one night or darkness period during the photosensitive phase of the plant can delay or disrupt flower maturation. Whereas exposure to just one or two periods of short days (long nights) may induce flowering. In day-neutral (autoflowering) plants, entering the flowering stage may be irreversible.
Typically, sun-grown Cannabis plants flower between June and September, depending on the latitude. The flowering stage may range from about 5 to 16 weeks, depending on the genetics and environment. After the initially developed flowers that have been pollinated produce their fruit and seeds, pistillate plants may continue to produce additional flowers while staminate plants die. Colder weather eventually kills pistillate plants unless they are grown indoors or artificially induced into a vegetative state.
After being grown, Cannabis plants may be harvested at full flowering or at the end of flowering for their fiber, seeds, or cannabinoids. Indicators that plant flowers are ready for harvest may include stigmas changing color or disappearing.
Photoperiod refers to a plant's response to the amount of light and darkness, to which it is exposed. Depending on the genetics, light exposure events will trigger transcription factors, which activate flowering genes within plants. Without being bound to theory, it is thought that light-sensitive chromophore moieties within a Cannabis plant's cytochrome protein molecules change form or state depending on the energy or wavelength of the light absorbed. The changed form of the cytochrome protein may then signal the relay pathways or initiate the biochemical reactions for the activation of flowering genes. Additionally, genetically determined biochemical oscillators responsible for the circadian rhythms within a plant may dictate the entrainment or synchronization of the plant's internal clock with its environmental light-dark cycle. Phosphorylation or other reactions affecting the regulation of gene expression through the binding rates of pseudo-response regulators may peak at different times throughout the day (i.e., 24-hour period), such as at night or during an interval of uninterrupted darkness, in accordance with the negative feedback loop of the plant's biological clock.
For example, short-day or long-night plants, as obligate photoperiodic plants, will only begin flowering once the sunlight hours are reduced to a certain number, based on the seasonal changes of the earth's orbit or artificial replication thereof. Typically, short-day plants will flower when the day is less than 12 hours (i.e., the night is longer than 12 hours) regardless of plant age or size. In indoor growing operations, this photosensitivity allows for a precisely tailored plant cycle for continuous growing seasons with the stages of development being artificially controlled. Additionally, when outdoors, short-day plants can be fooled into flowering early (i.e., outside of the natural seasonal schedule) by being covered for at least 12 hours in a 24-hour period. Similarly, if exposed to more than 12 hours of light in a 24-hour period, short-day plants will not flower, so flowering may be delayed and/or a plant may be kept in a perpetual vegetative state (e.g., as a mother plant for clones and/or seeds).
Autoflowering or day-neutral plants, by contrast, will flower regardless of day or night length, based on various factors including plant maturity, total amount of light exposure, angle of the sun, degree-days, and root system containment. Indoor growing operations can therefore cause day-neutral plants to flower quickly or early based on the amount of light exposure, even running grow lights constantly. Conversely, this means that day-neutral plants may not be preserved in a vegetative state and will flower no matter if placed in perpetual darkness or light.
All plants within the genus, Cannabis, are obligate photoperiodic plants, and more specifically, short-day plants, except for Cannabis ruderalis, which is day-neutral. The variety Cannabis ruderalis Janischewsky may be synonymous with C. sativa var. ruderalis Janisch, C. sativa subsp. sativa var. spontanea Vavilov, C. sativa var. spontanea Czernj., and C. sativa subsp. spontanea Serebr. Most Cannabis sativa plants flower when the length of continuous darkness exceeds about 10-12 hours per 24-hour period or when daylight lengths only last about 12-14 hours. Cannabis sativa seeds are generally planted between March and May and harvested about 6-8 months later, between September and November. Short-day Cannabis sativa plants may be induced into a vegetative state using a 16- to 24-hour lighting cycle. Day-neutral Cannabis plants will flower based on the maturity of the plant after germination and do not depend on a change in photoperiod, however, they tend to flower earlier with longer days.
Despite the autoflowering property of day-neutral Cannabis ruderalis plants, it tends to be a less desired variety of Cannabis plant due to its small yield and low cannabinoid content. Some breeders have produced autoflowering hybrids of Cannabis ruderalis and Cannabis sativa or Cannabis indica with a vegetative growth stage of only 6 weeks or about 45 days—e.g., strains such as Low Ryder and Auto AK-47. However, unlike the carefully selected clone mother plants of sativa or indica strains, autoflowering hybrids may not be kept in a vegetative state so that its desirable properties may be cloned from clippings. Further, within industrial fiber hemp growing, early flowering is considered undesirable due to its effect of halting stalk growth, thus limiting yield.
Cannabis ruderalis may be further differentiated from other Cannabis varieties by the morphological differences in its smaller achenes—formed with a constricted base, swollen abscission zone (eliosome), and mottled perianth, adherent to the achene—that separate from the plant after flowering and have a wider distribution in terms of germination. Cannabis ruderalis plants are shorter (typically less than 2 feet tall) and unbranched, but boast a higher resistance to cold and a faster maturation. For example, Finola is a strain of Finnish seed hemp that is early maturing (i.e., has a relatively short juvenile phase of about 13 days). The seeds of Cannabis ruderalis can survive freezing and in just 10 weeks, can complete their entire life cycle.
Cannabis plants uniquely contain C21 or C22 terpenophenolic chemical compounds known as cannabinoids—specifically, phytocannabinoids that naturally occur within the plant itself. Many Cannabis crops are harvested specifically to collect these cannabinoids for various downstream uses, so often plant varieties are bred to maximize their total cannabinoid yield. The phytocannabinoids within a Cannabis plant are secondary metabolites synthesized within glandular trichome cells and may include cannabigerolic acid (CBGA), which can be converted into cannabichromenic acid (CBCA), cannabidiolic acid (CBDA), and/or tetrahydrocannabinolic acid (THCA) depending on the type of enzymes present in the plant according to its genetics. Specifically, the oxidoreduction and cyclization of CBGA catalyzed by THCA and CBDA synthases provides the synthesis of THCA and CBDA. The phytocannabinoid content (e.g., THCA/CBDA ratio) resulting from the plant's genetics allow for classification of Cannabis plant types by discrete chemical phenotype or chemotype, as shown in Table A below.
TABLE A
CANNABIS PLANT TYPE CATEGORIZATION
Cannabis
Chemotype Phytocannabinoid Content Description
Type I THCA dominant
Type II Substantially equal parts CBDA and THCA
Type III CBDA dominant
Type IV CBGA dominant
Type V Cannabinoid free (i.e., containing terpenes but no
cannabinoids)
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CROSS-HYBRIDIZATION OF DISTINCT HOMOZYGOUS CANNABIS PLANTS TO PRODUCE CONSISTENT EARLY FLOWERING SEEDS
United States Patent Application 20190297821
Abstract:
A method for developing seeds for consistent early flowering short-day Cannabis plants, the method including crossbreeding a short-day Cannabis plant with a day-neutral Cannabis plant, and collecting the seeds produced through crossbreeding.
Inventors:
Crawford, Seth S. (Albany, OR, US)
Crawford, Eric B. (Corvallis, OR, US)
Application Number:
16/364715
Publication Date:
10/03/2019
Filing Date:
03/26/2019
Claims:
What is claimed is:
1. A method of developing seeds for consistent early flowering short-day Cannabis plants, the method comprising: crossbreeding a short-day Cannabis plant with a day-neutral Cannabis plant; and collecting the seeds produced through crossbreeding.
2. The method as claimed in of claim 1, wherein the short-day Cannabis plant is Cannabis sativa.
3. The method as claimed in claim 1, wherein the day-neutral Cannabis plant is Cannabis ruderalis.
4. The method as claimed in claim 1, further comprising selecting the short-day Cannabis plant based on at least one of resin levels, terpine profile, cannabinoid levels, and structure.
5. The method as claimed in claim 1, further comprising selecting the day-neutral Cannabis plant based on at least one of resin levels, terpine profile, cannabinoid levels, and structure.
6. The method as claimed in claim 1, further comprising inbreeding the short-day Cannabis plant prior to the crossbreeding.
7. The method as claimed in claim 6, wherein inbreeding includes: inducing staminate flowers on a pistillate plant; and pollinating pistillate flowers on the pistillate plant with pollen from the induced staminate flowers.
8. The method as claimed in claim 6, further comprising selecting the short-day Cannabis plant for inbreeding based on at least one of resin levels, terpine profile, cannabinoid levels, and structure.
9. The method as claimed in claim 6, wherein inbreeding the short-day Cannabis plant includes homogenizing the initial Cannabis plant for at least 3 generations.
10. The method as claimed in claim 1, further comprising inbreeding the day-neutral Cannabis plant prior to the crossbreeding.
11. The method as claimed in claim 10, wherein inbreeding includes: inducing staminate flowers on a pistillate plant; and pollinating pistillate flowers on the pistillate plant with pollen from the induced staminate flowers.
12. The method as claimed in claim 10, further comprising selecting the day-neutral Cannabis plant for inbreeding based on at least one of resin levels, terpine profile, cannabinoid levels, and structure.
13. The method as claimed in claim 10, wherein inbreeding the day-neutral Cannabis plant includes homogenizing the initial Cannabis plant for at least 3 generations.
14. The method as claimed in claim 1, wherein crossbreeding includes: inducing staminate flowers on a pistillate plant; and pollinating a second pistillate plant with pollen from the induced staminate flowers.
15. A Cannabis seed, developed from the crossbreeding of a short-day and a day-neutral Cannabis plant, comprising: early flowering characteristics, wherein the Cannabis plant grown from the seed will flower when exposed to a critical photoperiod that includes about 540 minutes of uninterrupted darkness.
16. The Cannabis seed as claimed in claim 15, wherein the short-day Cannabis plant is Cannabis sativa.
17. The Cannabis seed as claimed in claim 15, wherein the day-neutral Cannabis plant is Cannabis ruderalis.
18. A Cannabis seed obtained by crossing: a first Cannabis plant that is transformed preferentially to have a first homozygosity level and to express short-day characteristics, whereby flowering depends on a change in photoperiod; and a second Cannabis plant that is transformed preferentially to have a second homozygosity level and to express day-neutral characteristics, whereby flowering does not depend on a change in photoperiod.
19. The Cannabis seed as claimed in claim 18, wherein the first and second homozygosity levels are measured by genetic testing.
20. A method of producing an early flowering Cannabis plant, the method comprising: crossing a day-neutral Cannabis ruderalis plant with a short-day Cannabis sativa plant; recovering the resultant F1 hybrid Cannabis seed; planting the resultant F1 hybrid Cannabis seed and growing into plants; and selecting resultant Cannabis plant from the planting having a desired trait.
Description:
CROSS REFERENCE TO RELATED APPLICATION
This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/649,424 filed Mar. 28, 2018, which is incorporated herein by reference in its entirety.
TECHNICAL FIELD
This disclosure is directed to the production of seeds for early flowering Cannabis plants, and, more particularly, to a method of crossbreeding distinct homogenous species of photosensitive short-day Cannabis plants with day-neutral Cannabis plants to achieve a first generation of consistent early flowering Cannabis plants for optimizing field use and harvest yields.
BACKGROUND
Cannabis is a genus of plants useful in the industrial or artisanal production of oil, fiber, food, fragrance, and medicine. The various parts of Cannabis plants may be used in a near infinite number of products, such as fiber, oils, and medicines, for example.
As the number of indoor Cannabis growing operations expands, increasing amounts of energy and electricity are required for the lighting needs of the plants. With further legalization, it is expected that prices for Cannabis products will lower, making it harder for indoor operations to afford the overhead for their power costs and further incentivizing the switch to natural, outdoor growing. However, in contrast to the continuously controlled lighting cycles of indoor operations, outdoor growing is subject to the seasonal timing of natural sunlight cycles. Typically, sun-grown Cannabis is planted in spring, flowers when nighttime exceeds about 10-12 hours, and is ready to harvest in late autumn. Additionally, there has been significant variation in flower induction timing across and within Cannabis cultivars.
Accordingly, there exists a need to consistently shorten the time to harvest for sun-grown Cannabis crops while maintaining any desired traits and yield.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of example breeding results for day-neutral and short-day Cannabis plants, in accordance with the present disclosure.
DETAILED DESCRIPTION
Disclosed herein are systems and methods for producing complex hybrids of Cannabis plants that begin flowering when exposed to a light cycle including about 540 minutes (9 hours) of uninterrupted darkness. As explained in detail below, it has been found that crossing homozygous varieties of short-day Cannabis sativa with homozygous varieties of day-neutral Cannabis ruderalis results in consistent early flowering short-day Cannabis hybrid progenies.
This type of crossbreeding of Cannabis plants has not been found to work with varieties of mulberry and hops plants, which are the closest relatives to Cannabis plants, found within the Moraceae and Cannabaceae families.
Plant species in the genus, Cannabis, are annual plants that are wind-pollinated to produce seeds that germinate the following year. Cannabis plants are dicotyledons that bear fruit in the form of achenes, which consist of one seed protected by two cotyledons or bracts (i.e., embryonic leaves) as well as energy rich nutritional proteins with all the essential amino acids.
Cannabis plant species are dioecious, meaning that staminate plants with a male sex chromosome (i.e., XY) have male flowers containing microgametophytes within the pollen, and pistillate plants with only female sex chromosomes (i.e., XX) have female flowers containing megagametophytes within the ovules. Hermaphroditic plants and flowers are also possible in monoecious phenotypes, although they are generally sterile. Morphological differences for visually distinguishing between male and female plants develop during the reproductive stage.
The diurnal light cycle and/or exposure to low levels of carbon monoxide may change the gender expression of a plant. Feminized seeds may also be produced by treating isolated portions of female plants with hormones or silver thiosulphate to induce pollen formation.
The life cycle of Cannabis plants includes germination/emergence, vegetative growth, reproductive stages, in which flowers and seeds are formed, and finally, senescence. The time for maturation may vary from about 2 to 10 months, but naturally, the time from seed to harvest is about 8 months. However, artificial indoor growing operations can speed the life cycle of Cannabis plants to just 90 days by boosting light exposure and tightly controlling the timing of the required photoperiods (discussed in detail below).
Cannabis seeds mostly lack dormancy mechanisms and germinate without requiring any pre-treating or winterizing. Weights range from about 2 to 70 grams per 1,000 seeds. When placed in viable growth conditions, Cannabis seeds germinate in about 1-19 days.
The stages of vegetative growth include time as a juvenile (basic vegetative phase) and a photosensitive phase, lasting until the development of flowers. Vegetative growth may last for about 2-20 weeks, during which growth increases in response to temperature and increasing light exposure, and plants may be grown to their desired size. After the juvenile stage of about 1-8 weeks, plants require at least 12 hours of light before flowering may begin about 1-12 weeks later. Exposing the plants in the photosensitive phase to a critical photoperiod (e.g., about 14-16 hours of light) begins flower development. In general, about 18-20 hours of light per day during the vegetative growth stage has been shown to produce the highest yields for some Cannabis plant varieties. Interrupting the continuity of just one night or darkness period during the photosensitive phase of the plant can delay or disrupt flower maturation. Whereas exposure to just one or two periods of short days (long nights) may induce flowering. In day-neutral (autoflowering) plants, entering the flowering stage may be irreversible.
Typically, sun-grown Cannabis plants flower between June and September, depending on the latitude. The flowering stage may range from about 5 to 16 weeks, depending on the genetics and environment. After the initially developed flowers that have been pollinated produce their fruit and seeds, pistillate plants may continue to produce additional flowers while staminate plants die. Colder weather eventually kills pistillate plants unless they are grown indoors or artificially induced into a vegetative state.
After being grown, Cannabis plants may be harvested at full flowering or at the end of flowering for their fiber, seeds, or cannabinoids. Indicators that plant flowers are ready for harvest may include stigmas changing color or disappearing.
Photoperiod refers to a plant's response to the amount of light and darkness, to which it is exposed. Depending on the genetics, light exposure events will trigger transcription factors, which activate flowering genes within plants. Without being bound to theory, it is thought that light-sensitive chromophore moieties within a Cannabis plant's cytochrome protein molecules change form or state depending on the energy or wavelength of the light absorbed. The changed form of the cytochrome protein may then signal the relay pathways or initiate the biochemical reactions for the activation of flowering genes. Additionally, genetically determined biochemical oscillators responsible for the circadian rhythms within a plant may dictate the entrainment or synchronization of the plant's internal clock with its environmental light-dark cycle. Phosphorylation or other reactions affecting the regulation of gene expression through the binding rates of pseudo-response regulators may peak at different times throughout the day (i.e., 24-hour period), such as at night or during an interval of uninterrupted darkness, in accordance with the negative feedback loop of the plant's biological clock.
For example, short-day or long-night plants, as obligate photoperiodic plants, will only begin flowering once the sunlight hours are reduced to a certain number, based on the seasonal changes of the earth's orbit or artificial replication thereof. Typically, short-day plants will flower when the day is less than 12 hours (i.e., the night is longer than 12 hours) regardless of plant age or size. In indoor growing operations, this photosensitivity allows for a precisely tailored plant cycle for continuous growing seasons with the stages of development being artificially controlled. Additionally, when outdoors, short-day plants can be fooled into flowering early (i.e., outside of the natural seasonal schedule) by being covered for at least 12 hours in a 24-hour period. Similarly, if exposed to more than 12 hours of light in a 24-hour period, short-day plants will not flower, so flowering may be delayed and/or a plant may be kept in a perpetual vegetative state (e.g., as a mother plant for clones and/or seeds).
Autoflowering or day-neutral plants, by contrast, will flower regardless of day or night length, based on various factors including plant maturity, total amount of light exposure, angle of the sun, degree-days, and root system containment. Indoor growing operations can therefore cause day-neutral plants to flower quickly or early based on the amount of light exposure, even running grow lights constantly. Conversely, this means that day-neutral plants may not be preserved in a vegetative state and will flower no matter if placed in perpetual darkness or light.
All plants within the genus, Cannabis, are obligate photoperiodic plants, and more specifically, short-day plants, except for Cannabis ruderalis, which is day-neutral. The variety Cannabis ruderalis Janischewsky may be synonymous with C. sativa var. ruderalis Janisch, C. sativa subsp. sativa var. spontanea Vavilov, C. sativa var. spontanea Czernj., and C. sativa subsp. spontanea Serebr. Most Cannabis sativa plants flower when the length of continuous darkness exceeds about 10-12 hours per 24-hour period or when daylight lengths only last about 12-14 hours. Cannabis sativa seeds are generally planted between March and May and harvested about 6-8 months later, between September and November. Short-day Cannabis sativa plants may be induced into a vegetative state using a 16- to 24-hour lighting cycle. Day-neutral Cannabis plants will flower based on the maturity of the plant after germination and do not depend on a change in photoperiod, however, they tend to flower earlier with longer days.
Despite the autoflowering property of day-neutral Cannabis ruderalis plants, it tends to be a less desired variety of Cannabis plant due to its small yield and low cannabinoid content. Some breeders have produced autoflowering hybrids of Cannabis ruderalis and Cannabis sativa or Cannabis indica with a vegetative growth stage of only 6 weeks or about 45 days—e.g., strains such as Low Ryder and Auto AK-47. However, unlike the carefully selected clone mother plants of sativa or indica strains, autoflowering hybrids may not be kept in a vegetative state so that its desirable properties may be cloned from clippings. Further, within industrial fiber hemp growing, early flowering is considered undesirable due to its effect of halting stalk growth, thus limiting yield.
Cannabis ruderalis may be further differentiated from other Cannabis varieties by the morphological differences in its smaller achenes—formed with a constricted base, swollen abscission zone (eliosome), and mottled perianth, adherent to the achene—that separate from the plant after flowering and have a wider distribution in terms of germination. Cannabis ruderalis plants are shorter (typically less than 2 feet tall) and unbranched, but boast a higher resistance to cold and a faster maturation. For example, Finola is a strain of Finnish seed hemp that is early maturing (i.e., has a relatively short juvenile phase of about 13 days). The seeds of Cannabis ruderalis can survive freezing and in just 10 weeks, can complete their entire life cycle.
Cannabis plants uniquely contain C21 or C22 terpenophenolic chemical compounds known as cannabinoids—specifically, phytocannabinoids that naturally occur within the plant itself. Many Cannabis crops are harvested specifically to collect these cannabinoids for various downstream uses, so often plant varieties are bred to maximize their total cannabinoid yield. The phytocannabinoids within a Cannabis plant are secondary metabolites synthesized within glandular trichome cells and may include cannabigerolic acid (CBGA), which can be converted into cannabichromenic acid (CBCA), cannabidiolic acid (CBDA), and/or tetrahydrocannabinolic acid (THCA) depending on the type of enzymes present in the plant according to its genetics. Specifically, the oxidoreduction and cyclization of CBGA catalyzed by THCA and CBDA synthases provides the synthesis of THCA and CBDA. The phytocannabinoid content (e.g., THCA/CBDA ratio) resulting from the plant's genetics allow for classification of Cannabis plant types by discrete chemical phenotype or chemotype, as shown in Table A below.
TABLE A
CANNABIS PLANT TYPE CATEGORIZATION
Cannabis
Chemotype Phytocannabinoid Content Description
Type I THCA dominant
Type II Substantially equal parts CBDA and THCA
Type III CBDA dominant
Type IV CBGA dominant
Type V Cannabinoid free (i.e., containing terpenes but no
cannabinoids)