Well this leads me to ask this as it is a theory in MMJ growing as well is that if you have light leak in a your dark period you will have a herm how is that when in nature there is a moon which provides light during this natural dark period I believe it is a genetic issue Cannabis has been described as having one of the most complicated mechanisms of sex determination among the dioecious plants.Many models have been proposed to explain sex determination in Cannabis. Based on studies of sex reversal in hemp, it was first reported by K. Hirata in 1924 that an XY sex-determination system is present.At the time, the XY system was the only known system of sex determination. The X:A system was first described in Drosophila spp in 1925.Soon thereafter, Schaffner disputed Hirata's interpretation,and published results from his own studies of sex reversal in hemp, concluding that an X:A system was in use and that furthermore sex was strongly influenced by environmental conditions. Breeding systems
Cannabis sativa fruits (achenes) that contain the seeds.
Cannabis is predominantly dioecious,although many monoecious varieties have been described.Subdioecy (the occurrence of monoecious individuals and dioecious individuals within the same population) is widespread.Many populations have been described as sexually labile.
As a result of intensive selection in cultivation, Cannabis exhibits many sexual phenotypes that can be described in terms of the ratio of female to male flowers occurring in the individual, or typical in the cultivar.Dioecious varieties are preferred for drug production, where typically the female flowers are used. Dioecious varieties are also preferred for textile fiber production, whereas monoecious varieties are preferred for pulp and paper production. It has been suggested that the presence of monoecy can be used to differentiate licit crops of monoecious hemp from illicit drug crops.However, sativa strains often produce monoecious individuals, Cannabis has been described as having one of the most complicated mechanisms of sex determination among the dioecious plants.Many models have been proposed to explain sex determination in Cannabis.
Based on studies of sex reversal in hemp, it was first reported by K. Hirata in 1924 that an XY sex-determination system is present.At the time, the XY system was the only known system of sex determination. The X:A system was first described in Drosophila spp in 1925.Soon thereafter, Schaffner disputed Hirata's interpretation,and published results from his own studies of sex reversal in hemp, concluding that an X:A system was in use and that furthermore sex was strongly influenced by environmental conditions.
Since then, many different types of sex determination systems have been discovered, particularly in plants.Dioecy is relatively uncommon in the plant kingdom, and a very low percentage of dioecious plant species have been determined to use the XY system. In most cases where the XY system is found it is believed to have evolved recently and independently.
Since the 1920s, a number of sex determination models have been proposed for Cannabis. Ainsworth describes sex determination in the genus as using "an X/autosome dosage type".
Dense raceme of carpellate flowers typical of drug-type varieties of Cannabis.
The question of whether heteromorphic sex chromosomes are indeed present is most conveniently answered if such chromosomes were clearly visible in a karyotype. Cannabis was one of the first plant species to be karyotyped; however, this was in a period when karyotype preparation was primitive by modern standards. Heteromorphic sex chromosomes were reported to occur in staminate individuals of dioecious "Kentucky" hemp, but were not found in pistillate individuals of the same variety. Dioecious "Kentucky" hemp was assumed to use an XY mechanism. Heterosomes were not observed in analyzed individuals of monoecious "Kentucky" hemp, nor in an unidentified German cultivar. These varieties were assumed to have sex chromosome composition XX.[70] According to other researchers, no modern karyotype of Cannabis had been published as of 1996.Proponents of the XY system state that Y chromosome is slightly larger than the X, but difficult to differentiate cytologically.
More recently, Sakamoto and various co-authors have used RAPD to isolate several genetic marker sequences that they name Male-Associated DNA in Cannabis (MADC), and which they interpret as indirect evidence of a male chromosome. Several other research groups have reported identification of male-associated markers using RAPD and AFLP.Ainsworth commented on these findings, stating,
"It is not surprising that male-associated markers are relatively abundant. In dioecious plants where sex chromosomes have not been identified, markers for maleness indicate either the presence of sex chromosomes which have not been distinguished by cytological methods or that the marker is tightly linked to a gene involved in sex determination.
Environmental sex determination is known to occur in a variety of species.Many researchers have suggested that sex in Cannabis is determined or strongly influenced by environmental factors.Ainsworth reviews that treatment with auxin and ethylene have feminizing effects, and that treatment with cytokinins and gibberellins have masculinizing effects.It has been reported that sex can be reversed in Cannabis using chemical treatment.A PCR-based method for the detection of female-associated DNA polymorphisms by genotyping has been developed.
, but you won't find cannnabis growing 'naturally' out on the tundra.) )