In grain or pseudo-grain landraces, how would one go about selecting for uniform ripening? I’m particularly interested in quinoa; I’m starting out with a half-dozen different varieties, which may have different harvest dates. (I can’t find much firm information.) Due to the hectic nature of life and the variability of the weather, I’m sure I won’t end up harvesting the population at the same number of days after planting each year, so just harvesting won’t work to stabilize this trait. If it doesn’t become more or less uniform, I would lose a lot of the harvest each year, either due to shattering before harvest or lack of maturity in some of the plants.
I suppose I could let it stand as long as possible and select for durability in the field, but with our frequent summer thunderstorms that would be a risk. Or I suppose I could just select as early as possible each year, and so select out the later-growing populations—but in some cases, that would select for plants that yielded less overall.
In the book Shattering, they talk about how our ancestors determined maturity dates of grains by harvesting all at once. Over the years of harvesting around the same time of year, they selected for plants that were relatively uniform in maturity.
Initially if you’re starting out with a diverse mix, this can result in hard selection since you will be cutting out all genetics from plants that mature later, but it is what you want. If you want to keep the diversity, it’s best to make hybrids and save all the seed until you grow out the f2. Then select for maturity dates from that population.
The shattering trait will loose out simply because you are not saving for the shattering trait. If they shatter, they do not get collected and either must become weedy or will show up less and less. You get what you select for.