We’ve got another interesting study for cultivators. In 2023, researchers at the University of Connecticut tested how gene dosage at the autoflowering locus impacts flowering time and plant height in diploid and triploid cannabis. The headline for growers: triploid plants with one photoperiod allele and two autoflower alleles (Aaa) finished 15–40 days earlier than standard photoperiod types, without getting shorter. That means August harvests and fewer botrytis headaches, while preserving yield potential.

Why this matters in the field

Outdoor photoperiod crops in northern regions typically harvest late September to late October, right as frost, rain, and humidity push disease pressure (Fusarium, Botrytis) into the red. Autoflower strains can finish fast, but often at the cost of stature and yield. The Connecticut team set out to find a middle path: earlier finish times with photoperiod-like plant size.

The quick study recap (in grower terms)

  • Where & how: Greenhouse and field trials with thoughtfully structured crosses among autoflower and photoperiod parents; they confirmed ploidy with flow cytometry and tracked days to terminal flowering and plant height.
  • Genotypes compared:
    • AAA (triploid, all photoperiod alleles)
    • AAa (triploid, 2 photoperiod + 1 autoflower)
    • Aaa (triploid, 1 photoperiod + 2 autoflower)
    • Aa (diploid hybrid)
    • aa/aaa (diploid/triploid full autoflower)
  • Main finding: As the share of the autoflower allele increased, flowering happened sooner. The photoperiod allele shows incomplete dominance, which is why “in-between” dosages create “in-between” timing.

The grower-relevant numbers

  • Triploid Aaa initiated flowering 32–40 days earlier than standard photoperiod diploids (AA) in the field, and 15 days earlier than the diploid hybrid (Aa).
  • In Connecticut, Aaa peaked and was harvest-ready by the second week of August, well ahead of September rains.
  • Height: Aaa plants were as tall as diploid/triploid photoperiod-sensitives tested, pointing to comparable yield potential rather than classic auto-size reductions.
  • Greenhouse timelines echoed the field trend: as daylength stepped down (18 → 12 h), genotype order stacked from earliest (aaa/aa, then Aaa) to latest (AA/AAA).

What to do with this as a grower

  1. Target earlier, safer harvest windows. If your site historically battles late-season botrytis, Aaa triploids provide a path to August harvests, you’re pulling plants before nights cool and humidity spikes.
  2. Preserve canopy and yield potential. Unlike many fast autos, Aaa didn’t lose height in this research set, making it a better fit for existing trellis, spacing, and IPM routines designed around photoperiod vigor.
  3. Reduce seed risk with triploids. Triploid flower crops are often functionally seedless because odd chromosome sets create inviable gametes, insurance against pollen drift from neighboring fields.
  4. Plan labor and post-harvest earlier. Shift dry room capacity and trimming labor forward 3–6 weeks. Aaa genotypes showed uniform timing (all plants initiating on the same day in one cross), which simplifies scheduling.
  5. Mind your latitude and daylength. The field win was in Connecticut; your exact calendar will shift by location. But the relative order, Aaa < Aa < AA/AAA, should hold, giving you a reliable way to stagger finish times across blocks.

Buying & trialing: how to integrate Aaa triploids

Ask suppliers specifically about triploid Aaa genetics derived from a tetraploid autoflower × diploid photoperiod cross. That’s the recipe the study validated for early, tall plants. Start with side-by-side strips against your standard photoperiod cultivar to benchmark timing, canopy, and dry yield per square meter under your fertility and irrigation program.

Small-plot trial plan (practical and quick)

  • Design: 3 narrow beds or 3 greenhouse rows:
    • Row 1: your current photoperiod (AA)
    • Row 2: your best hybrid (Aa, if available)
    • Row 3: candidate triploid (Aaa)
  • Metrics to capture: calendar dates for first pistils on apical tips (terminal flowering), peak flower, plant height at peak bulking, percent incidence of Botrytis at harvest, wet and dry weight, and labor hours for harvest per row.
  • Decision rule: If Aaa gives you ≥ 2–3 weeks earlier harvest and similar dry weight per m² with lower mold culls, scale up next season.

Crop steering & IPM pointers for earlier finishers

  • Veg duration: With earlier transition to reproductive growth, watch for shorter veg. Ensure root zone vigor is established quickly (warm media, adequate VPD, and early balanced nutrition). Triploids in this work didn’t trade height, but fast early growth still matters.
  • Nutrition: Pull your bloom transition feed curve forward 1–2 weeks. Earlier K and micronutrient availability can support resin and calyx development on the accelerated timeline.
  • Defoliation timing: Move your structural strip/leaf thinning earlier to keep airflow high during the compressed bulking window. You’re harvesting sooner, don’t invite microclimates.
  • IPM: Because you finish before peak pathogen season, you may be able to reduce fungicide intensity late cycle; still, keep canopy VPD and night temps in check to lock in the advantage.

Breeder’s note (for those making the seed you buy)

The most actionable pathway from this study for creating market-ready early finishers is tetraploid autoflower (aaaa) mother × diploid photoperiod (AA) pollen → triploid Aaa seed. It consistently produced earlier flowering while matching height of photoperiod genotypes, an attractive foundation for commercial flower programs.

What this does not change (manage expectations)

  • Autos vs. Aaa triploids: Full autos (aa/aaa) still flower the earliest but tend to be smaller and can trigger too fast under stress. Aaa offers a middle lane: early and tall.
  • Quality specifics: This paper focused on timing and height. Cannabinoid/terpene data were not the endpoint here; run your own QC to lock in potency and terpene targets under your environment.
  • Site dependence: The field success was in New England. Expect similar ordering across genotypes, but adjust calendar dates to your latitude and season length.

Fast FAQ for growers

Will Aaa triploids hurt my yield?
In this research set, Aaa plants were as tall as the diploid and triploid photoperiod-sensitives, which suggests comparable yield potential, while finishing weeks earlier.

How much earlier can I harvest?
Field Aaa plants initiated flowering 15 days earlier than Aa and 32–40 days earlier than AA, finishing by mid-August in Connecticut.

Do triploids really help with seedlessness?
Triploids often show dramatically reduced seed set due to meiotic imbalance, useful insurance where pollen drift is a risk.

What’s the exact buying cue?
Look for triploid (Aaa) early-flowering lines produced from a tetraploid autoflower × diploid photoperiod cross; ask vendors to confirm genotype strategy and field timing data.

Bottom line for this season

If late-season disease has been taxing your outdoor or hybrid greenhouse flower runs, trial a triploid Aaa line next to your standard photoperiod cultivar. You’re aiming to move harvest up by 3–6 weeks, maintain plant size, and drop mold losses, all without overhauling your entire program. That’s the practical promise of gene-dosage steering at the autoflowering locus for working growers.

Source: Kurtz, Brand, & Lubell-Brand, “Gene Dosage at the Autoflowering Locus Effects Flowering Timing and Plant Height in Triploid Cannabis,”J. Amer. Soc. Hort. Sci. 148(2):83–88 (2023). Field and greenhouse results summarized above, including genotype ordering, August harvest readiness for Aaa in Connecticut, and height comparisons, are drawn directly from the study’s figures and tables.