Growing your own is legal in the Golden State, but it remains illegal under federal law. I planted my first seed on Oct. Based on the grow guide included in my kit, my plant would be ready to harvest just before Christmas. Fast-forward two months and, instead of the towering THC-laced tannenbaum I was hoping for, I was headed into Christmas week with a seedling — all of 5 inches tall — curving out of its pot at a degree angle.
Since A Pot for Pot purchases include growing consults via email, I sent off a few photos and a plea for help. What a cute little plant! But the silver lining, as Taylor pointed out, was that because of her stunted size, there would be more than enough nutrients in the soil mix to support a second attempt in that same pot. So after a few weeks of mourning, I decided to give pot-plant parenting a second try.
And this time around, I was determined to spare no expense — potential tax savings be damned. I invested in a bathroom scale so I could weigh the plant between waterings, and when Taylor offhandedly suggested an LED grow light so I could raise my little green girl indoors, I immediately ordered one and cleared a spot in my garage, not far from where my hard-partying friends used to routinely smoke plants like her in the pre-pandemic days.
And that six-plant limit? She made the velour tracksuit an L. Now she reveals her second act. Mother-son pot entrepreneurs? Vape pens that match your track pants? We have questions. Taken altogether that means your ability to become a legal pot-plant parent in L.
In mid-January, I planted my second seed. When she burst forth from the soil Jan. Eager to avoid my earlier mistake, Diana Prince was transplanted to her forever home just five days later and then locked safely in my garage under the new grow light 20 hours on, 4 hours off. I visited my baby daily, watering her just enough to keep her healthy and thriving.
By late March, Diana Prince was stretching skyward and entering her flowering stage. Two months later, she was nearly as tall as me and appeared ready to harvest. Even the most established labs, located in California, have only been around since the mids — despite the state legalizing the medical use of cannabis in That led to labs being set up quickly with old equipment in unsuitable spaces, and with minimal quality control. James says that, in the past, it was not uncommon to meet people at trade shows who had bought analytical kits on the online auction site eBay and were running testing labs from their bedrooms.
Cannabis analytical labs are becoming more professional. Such labs are beginning to adopt standardized tests for potency and purity using gas chromatography and high-performance liquid chromatography.
They are also developing methods to identify and measure levels of THC and other cannabinoids, as well as contaminants such as heavy metals and pesticide residues. It covers all phases of lab operation, including staff training, data protection and dealing with conflicts of interest.
More from Nature Outlooks. Although many small-scale cannabis growers at first questioned the need for intensive product testing, most can now appreciate the benefits that the rules bring to the market.
And as testing becomes more widespread, its importance is also reaching users, says Marcu. One sign of progress is that cannabis products can be recalled when they fail testing, just like other medical or consumer items.
In December and January , Organigram had to recall some of its products when residues from pesticides not approved for use in cannabis were detected.
As the cannabis industry expands, the role of good science within it will also expand, and there will be further opportunities for collaboration. This article is part of Nature Outlook: Cannabis , an editorially independent supplement produced with the financial support of third parties.
About this content. Article 10 NOV Article 03 NOV News 30 SEP Correspondence 06 SEP News Explainer 10 NOV World View 09 NOV Outlook 27 OCT Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily. Advanced search. Skip to main content Thank you for visiting nature. Seedlings from hermaphroditic seeds, and anther tissues, showed a female genetic composition while seedlings derived from cross-fertilized seeds showed a male:female sex expression ratio.
Uniquely, hermaphroditic inflorescences produced seeds which gave rise only to genetically female plants. In PCR assays, a bp size fragment was present in male and female plants, while a bp band was uniquely associated with male plants. Sequence analysis of these fragments revealed the presence of Copia -like retrotransposons within the C.
The extent of genetic variation after one generation of selfing in the progeny from hermaphroditic seed is similar to that in progeny from cross-fertilized seeds.
It has been proposed that dioecy is a basic evolutionary mechanism to ensure cross-fertilization and, as a consequence, results in maintenance of high genetic diversity and heterozygosity Dellaporta and Calderon-Urrea, ; Hamrick and Godt, ; Ainsworth, Sexual dimorphism is expressed at very early stages of organ initiation or specification, with differential expression of genes in male and female tissues Moliterni et al.
Sex determining chromosomes have been reported in 40 angiosperm species, with 34 species having the XY system which includes C. In this species, the karyotype consists of nine autosomes and a pair of sex chromosomes X and Y Sakamoto et al.
Female plants are homogametic XX and males are heterogametic XY , with sex determination controlled by an X-to-autosome balance system Ming et al. The estimated size of the haploid genome of C. The development of molecular markers linked with sex expression in hemp was described in earlier work by Sakamoto et al. Similar studies on marijuana are described in Punja et al. Marijuana plants are grown commercially for their psychoactive compounds, which are produced in the trichomes that develop on flower bracts in female inflorescences Andre et al.
On occasion, it has been observed that hermaphroditic inflorescences can develop spontaneously Small, These plants produce predominantly female inflorescences, but anthers ranging from a few to many may develop within the leaf axils or in pistillate flower buds.
These hermaphroditic inflorescences can be induced by exogenous applications of different chemicals Ram and Jaiswal, , ; Ram and Sett, , and by environmental stresses Rosenthal, ; Kaushal, , suggesting that external triggers and epigenetic factors may play a role.
The hermaphrodite plants are functionally monoecious due to their ability to undergo self-pollination, but the impact of self-fertilization on progeny sex ratios and on genetic variation in the subsequent progeny has not been previously studied.
There are no previously published reports which describe the morphology of hermaphroditic inflorescences in marijuana plants. In the present study, we describe the morphological features of this unique phenotype. Anther formation, pollen production and germination were studied using light and scanning electron microscopy. We also describe for the first time the effect of hermaphroditic seed formation on the resulting female:male sex ratio using a PCR-based gender identification method.
We assessed the extent of genetic variation in the progeny from self-fertilized seeds and compared that to seed derived from cross-fertilization using inter-simple sequence repeats or microsatellites ISSR markers. This study is the first to characterize the outcome of hermaphroditism in C.
The results have an important bearing on the utility of hermaphrodites for the production of feminized selfed seed in the cannabis industry. The plants were initiated from rooted cuttings and provided with the nutrient regime for hydroponic culture as described elsewhere Punja and Rodriguez, Lighting, temperature and growth conditions were provided in accordance with industry production standards to ensure pistillate inflorescence development Small, Figure 1.
The production system for marijuana plants based on vegetatively propagated plants that are first grown under a 24 h photoperiod for 4 weeks and then switched to a 12 h dark h light regime. C—K Sequential progression of development of pistillate inflorescences on female plants of marijuana grown under indoor conditions.
C Young terminal inflorescence with white hair-like stigmas. D More advanced inflorescence with yellowish-white clusters of stigmas. The stigmas are bifurcate at the tips. E Fully developed inflorescence. F Young terminal inflorescence with developing hair-like stigmas.
G More advanced inflorescence with yellowish-white clusters of stigmas. Subtending bracts have accumulated a purple pigment. H Fully developed inflorescence. I—K Show stages of maturation of inflorescence. I Early. J Mid. K Late. This flower bud is close to harvest and the carpels have swollen. The sequential development of the female inflorescence in marijuana strains is illustrated in Figure 1. At the early stages of development, the clusters of pistils with protruding stigmas on terminal inflorescences were yellowish-white in color Figures 1C—E.
In some strains where pigmentation was a characteristic feature, the pistils and surrounding bract tissues developed a red or purple pigmentation Figures 1F—H. With further maturation of the inflorescence, the stigmas shriveled and developed a brown-red color, while the ovules and surrounding bracts swelled and were covered by glandular trichomes that imparted a silvery-white appearance Figures 1I—K.
During the 6—7 weeks flowering period of strains grown under commercial conditions, female inflorescences were examined at weekly intervals visually with the aid of a hand lens for the development of male anthers within the inflorescence Figure 2. Around 1, plants in total were examined over the course of two repeated cycles of plant production in the study. Individual clusters of anthers appeared bright yellow and measured 2—3 mm in length Figures 2A—D and were formed within the bract tissues and surrounded by stigmas.
In some cases, the entire female inflorescence was converted to a mass of anthers which emerged through the bracts Figure 3. They were carefully removed with a pair of forceps, placed inside plastic petri dishes lined with moistened filter paper, and transported to the laboratory for microscopic examination. Scanning electron microscopic observations of anthers and pollen grains were made following preparation of the samples according to the procedure described by Punja et al.
Percent emergence of pollen tubes was rated from grains examined under an inverted compound light microscope Zeiss. The experiment was conducted twice. In instances where seed formation was observed in the inflorescences of the three strains, they were collected at fruit maturity, counted, and set aside.
The seedling tissues young leaves , as well as anther tissues from hermaphroditic flowers, were used for DNA extraction minimum of 15 seedlings per strain as described below. Figure 2. Male anthers and pollen production in hermaphroditic inflorescences of Cannabis sativa.
B,C Close-up of clusters of anthers formed within the calyx tissues adjacent to the brown stigmas. D Pollen production and release from anthers along the line of dehiscence that appears as a longitudinal groove stomium. Figure 3. The spontaneous conversion of a female inflorescence to produce anthers. A Initial clusters of anthers forming within the calyx that normally surrounds the ovary.
B Advanced stage of development of anthers in large clusters on the same plant shown in A,C,D Close-up of masses of anthers replacing the female inflorescence. E,F Mature anthers that have become dried. The transition from A—F occurs over 3 weeks. At least 20 seeds were germinated and 15 seedlings were obtained for each strain. The seedling tissues were used for DNA extraction as described below.
These appeared as characteristic clusters of anthers followed by release of pollen Figure 6. Individual clusters of anthers were carefully removed with a pair of forceps and brought to the laboratory for microscopic examination for the presence of pollen grains and for DNA extraction.
In addition, scanning electron microscopic observations of anther and pollen morphology were made following preparation of the samples according to the procedure described above. A minimum of five replicate samples were included. The primers amplified a bp sized DNA fragment in female plants, while in male plants, either two bands of and bp in size were produced, or just the bp band was amplified Punja et al.
The purified DNA was sent to Eurofins Genomics for sequencing in both the sense and antisense directions. Sequence files were processed and aligned, and the consensus sequences were extracted using Geneious Prime software by Biomatters Ltd. Geneious Prime All sequences from the different strains representing female and male plants were aligned using the Geneious Prime multiple alignment function.
To compare the genetic variation among bands represented by the bp size following PCR, an additional 10 strains of marijuana were chosen. All of the strains were genetically female, i. The plants were initiated from vegetative cuttings and were grown under hydroponic conditions or in the cocofibre:vermiculite mix and provided with the nutrient and lighting conditions for commercial production by a licensed producer as described above.
Each PCR reaction contained 0. After amplification, each PCR reaction was subjected to electrophoresis on a 1. Only well-separated bands of 0. Each set of experiments was repeated to ensure consistency of results. A total of 25 loci were analyzed. These statistics were calculated between groups strains and between populations hermaphroditic and cross-fertilized. Hardy-Weinberg equilibrium and random mating were assumed for both hermaphroditic and cross-fertilized populations.
All C. The production system for marijuana plants is based on vegetatively propagated plants that are first grown under a 24 h photoperiod for 4 weeks and then switched to a 12—14 h dark—12 h light regime. Figure 1B shows development of large terminal inflorescence clusters in some strains, e. The sequential development of the female inflorescence in several marijuana strains is shown in Figures 1C—K.
At the early onset of flower development weeks 1—2 of the flowering period , young terminal inflorescences developed white hair-like stigmas Figure 1C. In subsequent weeks 3—4, development of yellowish-white clusters of stigmas which were bifurcate at the tips can be seen Figures 1D,E.
This stage was the most receptive to pollination authors, unpublished observations. In red and anthocyanin-accumulating strains, stigma development was similar over this time period, and at advanced stages of inflorescence development, the yellowish-white clusters of stigmas were accompanied by red or purple pigmentation in the style tissues or subtending bracts Figures 1F—H. The mature inflorescence close to harvest weeks 7—8 with collapsed stigmas and swollen carpels is shown in Figure 1K.
Female inflorescences of three marijuana strains grown under commercial conditions were visually examined at weekly intervals. The anthers were visible in weeks 4—7 of the flowering period and were present until harvest. In rare instances, the entire female inflorescence was converted to large numbers of clusters of anthers Figure 3.
Scanning electron microscopic examination of the stigmas that were present in hermaphroditic flowers showed the papillae stigmatic hairs Figure 4A , which in mature inflorescences originated from a central core Figure 4B. Individual anthers that were produced in hermaphroditic inflorescences were shown to consist of an outer wall epidermis and endothecium with a longitudinal groove stomium Figure 4C which, upon maturity, expanded and dehisced to release pollen grains Figure 4D.
Bulbous structures presumed to be trichomes were also observed forming along the stomium of the anther Figure 4E. When viewed under the light microscope, the anther wall and stomium could be seen and pollen grains were released into the water used to mount the sample Figures 5A—C.
Some pollen grains had collapsed when viewed under the scanning electron microscope Figure 5D. Figure 4. Scanning electron microscopy of the stigmas and anthers in hermaphroditic flowers of Cannabis sativa. A Young developing stigma with receptive papillae or stigmatic hairs arrow. B Older stigma in which the stigmatic hairs are coiled and collapsed around a central core. C Individual anther prior to dehiscence showing an outer epidermis with the beginning of a longitudinal groove stomium arrow.
D Mature anther that has dehisced and revealing pollen grain release arrow. E Enlarged view of the stomium showing formation of bulbous trichomes arrow forming in the groove. Figure 5. Light and scanning electron microscopic observations of anthers and pollen grains in hermaphroditic flowers of Cannabis sativa. A The anther wall and groove are visible and pollen grains can be seen packed within the anther pollen sacs arrow. B Release of pollen grains into water used to mount the sample.
C,D Intact and collapsed pollen grains as viewed in the light microscope C and the scanning electron microscope D. Figure 6. Flower and pollen development in genetically male plants of Cannabis sativa. A—C Male flowers formed in clusters at leaf axils. Each flower is pedicillate, with individual stalks. D—F Opening of male flowers to reveal 5 green-white tepals which expose 5 stamens each attached to a filament that dangles the anther.
G Large amounts of pollen arrow being released through the longitudinal groove stomium of the anther. H Enlarged view of the stomium showing formation of bulbous trichomes arrow forming in the groove of the anther. I Close-up of a trichome with a short stalk arrow. Pollen grains can be seen in the foreground. In genetically male plants, anthers were produced within clusters of staminate flowers that developed at leaf axils Figures 6A—C at around 4 weeks of age. At flower maturity in weeks 4—6, anthers dangled from individual flowers and were observed to release large amounts of pollen grains, which were deposited in yellow masses on the leaves below Figures 6D—F , 7.
Such prolific release of pollen was not observed from the hermaphrodite flowers. Scanning electron microscopic examination of the anthers produced on staminate plants showed the release of pollen grains Figure 6G. Along the longitudinal groove or stomium, the formation of a line of bulbous trichomes Figure 6H that developed on a short pedicel Figure 6I was observed, similar to that seen in hermaphroditic flowers.
When pollen from male plants was deposited onto female inflorescences Figure 8B and viewed at 72—96 h, various stages of pollen germination and germ tube development were observed Figures 8C—F. Figure 7. Comparative growth of male M and female F plants of C. Plants originated from one seed batch produced from cross-fertilization that yielded male and female plants in approximately equal ratios. Seeds were planted at the same time and grown under a 24 h photoperiod for 4 weeks.
Figure 8. Light and scanning electron micrographs of pollen germination in Cannabis sativa. B Female inflorescence showing protruding receptive stigmas. The flower heads were excised and pollinated in vitro using pollen collected from a male flower.
C—F Pollen germination and germ tube development on stigmatic papillae in situ. Arrows show pollen grains in C,D and germ tube growth in E,F.
Within the hermaphroditic inflorescences in which anthers were found, seed set was initiated, and mature seeds were observed prior to the harvest period Figures 9A,B. From each of 3 inflorescences bearing seeds, a total of 34, 48, and 22 seeds were obtained.
Figure 9. Seed formation within hermaphroditic inflorescences of Cannabis sativa. A Longitudinal section cut through the female inflorescence showing outer protruding stigmas and unfertilized ovules. B Seed formation within a hermaphroditic inflorescence after 3—4 weeks.
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