My bud are too small. Which parameters are related to that ? Yes or no for each question and elaborate if possible. Have other ideas ? Thx !

these look like they have a lot of time left -- at least the ones i saw with long white hairs still portruding from calyxes... so don't judge yet. light will control excessive stretching. more intense light will reduce resulting internode length (internode - space between nodes) as far as what we can control, light is the single most important factor to yield. As far as quality, you just need some minimum to avoid larfy/poor growth/stagnating etc. (greater than 21 DLI is suggested... up to 40ish DLI w/ambient co2 and 55ish DLI with co2+controlled temps/rh) DLI is a more apples to apples comparison -- regardless of size and hours of use, it is simply comparing the amount of energy given to the plant in a highly resolved way relative to photosynthesis per 24 hour cycle. this powers production of sugas, which in turn releas energy when broken down to power production building blocks of cell growth. pot size is a bit small but you are hydro so frequent irrigations could mitigate that issue quite a bit. plants don't normally gow 70cm tall in 0.7gal pots. lil stretchy but doesn't sound severely stunted by the pot size, either. A little larger might do you good, reduce effort maintaining water levels later on etc... hydro doesn't need as large of a pot. defo doesn't do as much as we thinkg... probably end up with a slightlay smaller harvest but greater proportion of non-larfy buds... just a guess.. i'd love to see some proper statistical analysis on this because it's going to be fairly consistent and straight-forward once someone does it with a suitable sample size and employing the scientific method. i still liike to defo because i don't cook or do anythign with larf.. i don't want it around. don't want to be bothered by it. others see great value in it. so, personal preference will matter here as far as what you want to do... if you want to try it... the week leading up to flip or even a few days after, keep 2-3+ nodes up top (the later you do this, the more nodes you leave). be systematic and it's easy to adjust next time based on results. can be less extreme too.. remove any lanky stuff below some depth on plant etc etc... you can see on your plant right now... there's a virtual horizontal line where things get a bit too larfy below that line... that's the stuff i want to eliminate before it grows out. it's not easy guesstimating stretch on a plant you've never grown before, though... this won't be the reason your yield is low... that will be the light, if it ends up true (again, lots of ripening left.. the "fast" plants aren't always fast) ignore breeder guesstimate on flower time. use density, pistils and trichomes to determine it... if you look at trichomes too early, you will find amber on older growth, which is then covered up by more plumping calyxes with less mature trichomes that you can see. topping -- just make sure you give time before flip with photos.. with autos, i'd be hesitant to top after 3-4 weeks but some contine with strong vege growth for up to 7. you want enough days after topping of vege growth or it'll probably hurt yield more than help it. 14 days? with photos i top in the week leading up to flip. i've done it after, too, but i usually have 3-4 more weeks of good vege growth when i do top. pk at wrong time... if it burns the plant it's not timing. if you want to boost it, slowly ramp up as vege growth ceases... that's the supposed logic behind it... though i have severe doubts about how drasticalyl the needs of a plant change from vege to bloom... cell organelles do not change their stripes. the components of cells are still significantly the same. so, i don't think someone with a biology degree theorized this one..rather someone guessing with no clue whatsoever.. this common belief wreaks of the stench as "end of harvest flushing" has. i am a minority on this... so do as you choose.. but proof is in pudding.. if you boost pk and the canopy burns, that can't be good. so, if you do do it, be willing to adjust so that you have minimum leaf damage. a little tip bun is fine... losing large chunks of canopy's ability to photosynthesize can't be a net positve... no fucking way. LOL again, unsubstantiate opinion, but educated guess as i have take a fair amount of undergrad biology (tho, 25 years ago). google dli... figure out umol/s your equipment provides... do the math, if concerned about how much light you provide per day... when you drop to 12/12 from 18/6, you need 150% more to match what you provided over 18 hours in just 12 hours. (proportional to hours of use, so if oyu use different cycles, u have to do the math) from 20/4 to 12/12 it'll need 167% to give same DLI. this is the only way to talk apples to apples in this regard... otheriwise area of coverage and hours of use muddy the picture. photons per second per area and how many hours of day adds up to the energy provided. 1m^2 / 'your area in m^2' then multiply that by your umol/s produced = PPFD .. after that it's just referencing a DLI table. crossreference hours and PPFD to see resulting DLI -- still have to raise/lowe to match area of coverage in an optimal way... expect a little lower DLI tan what ayou calculate because not all photons produced by yourlights will hit the plant... some miss, some get absorbed by walls etc etc. so, good to shoot a bit over 5-10%. 40-42 DLI is usually a bit more than most can give relative to environmental factors.

1. The size of the pots (3L but plants are 70cm). Yes: 3L is a very small pot size unless your trying to do SOG, I like to place any plant in min 3gal or 11L ideally 5-7gal in the end for photoperiods. Bigger medium/roots equals bigger plants 2. They streched too much during veg & I have to many plants (12 in 40x90cm) yes/no: stretching is normal and it does not create more plants but does take up more canopy room. This will be hard for some of the plants to get all the lights to photosynthesize but is not the sole reason. 4. I didn't prune & defoliate enough at the base of the plants no: you can do that right now. thent he plants will put that energy into the remaining top buds but if it to far into flower it might stress it to much. 5. I pruned too much on top no: topping autos is not ideal in most cases but given you are doing photoperiods this should only help create a large more lush canopy that will be density packed. given the small pot size though that means they will be drying out fast and need lots of water/feed in lower doses. 6. Pk at the wrong time maybe? I don't use a PK booster so cant say. One thing that is missing though is your lights and how big of a role it plays. 205w for multiple plants is a but under spec for them. Ideally 100w per plant when growing them out. If you train your plants well you can get 2 big ones in a 2x4 tent or a bunch of smaller ones. I would aim to use bigger pots in the next grow and try and focus on one to three plants and use the SCROG method to fill your canopy. I think you will like the results, you can also combine that with some LST or HST to get some interesting effects like mainlining. I did this exact thing in my blue cindy journal and it would out very nice for me. I vegged it to long but in the end it was great. Good Luck & Happy Growing. **disclaimer, multiple people are answering all questions as there is a contest called GOTM, when a user is selected as the answer they get a point. Please see the contest page for information regarding the details:** growdiaries.com/giveaways/GotM-August-2022

There's no way to adequately answer this as genetics plays a vital role. You've got a lot of ideas as to how to increase your bud size so do an experiement... plant six of the same seeds (at the same time or at different times) and test out each one of your hypotheses to see what the difference is for YOU. I've grown two seeds together, one in a 3 gallon, one in a 5 gallon... made absolutely no difference to MY grow... the plants essentially yielded the same for ME... All that being said, you'll find increased light will give you increased yield most all the time... but increasing by 40w isn't going to do much... Good luck

And as it's environmental conditions answer week, I'll throw in a did you monitor VPD day and night cycle during the grow? For free.

You forgot not enough light for all them plants from a feeble centre tent LED and all above 👍 Next grow will be the one 😉 Be lucky

I'm confused as to what the question is? It seems you have answered it yourself. Big plants in small pots that haven't been lollipopped will give your plant the least chance of having big main colas, but as always genetics plays a big role in the size and shape of flower too.