It's far from ideal working with a small number of plants. Only way to really test a male is to grow, flower, dry and test the product of its offspring and compare that to the results with other males, but yeah space limits. The male I used I picked solely because it has plenty of red streaks, opposed to the other two I flowered. Not even sure I will grow the offspring, I’ll probably pop more of the ones I got going now, knowing now there will be plants from which I want to take clones (good bud structure and size and frosty but still at least pink).
With limited plants "How to pick a good male" becomes more an exercise of trying to avoid picking bad males and use the last man or men standing.
I normally go by structure, squat bushy, or tall lass branch depending on what female I’m going with.
That right there. It becomes easier when you're familiar with the parents of the plants you're selecting from. I've done so many runs and generations of my P cross I even looked at stipules eventually. The better more vigorous ones with great calyx to leave ratio usually had longer vigorous frosty uhm… ‘fully erect’ stipules. So in next or previous generations I preferred male plants that had that too. Same with leaf serrations. Some have double, some are more pointy or curvy. Especially when there’s clear difference in the parents it can help to recognize and select males that in that regard look most like their most desirable sister (the female in your quote).
Rubbing the males was far more useful for my P cross to exclude males than selecting the best. All the males smelled like strong pine in veg already, but some had this dank darker pine smell. Which later on seemed to be linked to a similar unpleasant dark taste/smell in buds, so it became an easy way to exclude at least a couple of the males.
It depends a lot on your goals and personal preferences but in addition to what you mentioned already:
- The firsts ones I cull are the 1-2 that haven’t shown its sex while the rest has. (when I still have a roughly equal amount of females and males). If there’s one or two clearly ahead of the rest I might cull those too. Basically when it comes to time to mature and transition (and in case of females flower duration) I avoid extremes. 44 days flower period is fun, but it comes at a cost in yield and probably potency too.
- Hollow vs non hollow stems in combination with wall thickness. I don't mind hollow stems but if I bend and pinch during veg/transition and they don't stand up again the next day but fold like a plastic straw instead, they're definitely out.
- I like some stretch during veg but especially those that clearly stretch more than others during transitioning I tend to remove, again selecting against extremes rather than the ideal plant.
- In addition to stretch of plant stems, the length of petioles (leaf stalks). I tend to push my males in the corner so they stretch even more on top of already being larger than females. Just leaves looking for more space/light, by itself a good thing if the neighboring plants were not cannabis. The way I crowd my plants, especially males, tends to enhance the extremes and there's always one or two that gets too lanky, not just stems but petioles too.
- Frost. Not always a great available option but sometimes I get males with trichomes all over, sometimes just looking at stipules of otherwise similar males can help at least (whether it’s effective in the offspring is another thing). Taking macro pics helps.
- Roots. Often easier on hydro or even mediumless or transparent containers my lazy ass uses. Usually the males that seem less vigorous on top also have less roots but sometimes, everything else being more or less equal, it’s another influential trait to compare.
Just some things to consider when you're in a luxury position where multiple males stand out overall or need to cull some males earlier on.