I am posting a side project into the feasibility of “microbreeding,” with (relatively) large populations of plants, during which I am playing with the development of a heterogeneous autoflowering hemp population on a micro (2x4 grow tent) scale.
Cycle 1: initial cross
I began with 18 CBD-1 females (autoflowering, CBD dominant (type 3) plant) crossed to 3 males (photoperiod, THC dominant (type 1) plants):
-THSeeds Heavy Duty Fruity (true male)
-DNA genetics Golden Lemons x unknown male (true male)
-Grandaddy Purple Candyland reversed female clone
Cycle 2: F2 seed production
I then grew out (to completion) this F1 seed in 4, 72 cell trays(288 seeds) and switched to 12/12 at week 2 from emergence. Plants were allowed to open pollinate with natural males present. Seed was retained separately from individual female plants.
Cycle 3: Selection for autoflower
F2 seed was grown in 4, 72 cell trays again (288 seeds planted), representing 6 seeds from each of 48 female lines from cycle 2 (48 of the 288 cycle 2 seeds planted were females that made seed). the light cycle was left as 18/6 throughout. Photoperiod plants were culled. Autoflowering plants were again allowed to open pollinate with natural males. Seed was retained separately from each female plant.
Cycle 4: CURRENT CYCLE; feminization of population
F3 seed is currently being grown out in 4, 72 cell trays again. 288 seeds were planted, representing 2 to 30 seeds from each of 21 F2 plants (21 of 288 F2 seeds planted were autoflowering females that produced seed). Males are rouged upon sexing. Once all plants are sexed and only females remain, all will be reveresed and allowed to open pollinate.
Cycle 5: FUTURE. No longer micro?
A few hundred F4 seed will be grown in a greenhouse in 1 to 3 gallon pots and resulting plants tested for CBD/THC content. At this point all plants should be autoflowering, but will hopefully be segregating for THC and CBD content. High CBD plants will be selected for selfing and all others destroyed.
Cycle 6: FUTURE
S1 seed (from selfed F4 plants) can be grown out and evaluated for superior lines.