Grain Amaranth

[S.Simonsen]

This is one of the few grain crops that performs fairly consistently in my humid subtropical zone with high bird pressure. My main productive strain is the orange Hartman giant, which I like because it is tall enough to canopy over our weeds. I did get exceptional yields from Oscar Blanco many years ago but remember it being quite short and requiring more vigilant weeding (not to mention awkward harvesting).

A couple of questions for those who might know more:
1. How does one go about encouraging hybridisation between different amaranth strains (short of extremely fiddly hand pollination)?
2. I have noticed inconsistent germination of seed, with them coming up more readily on soil that is either fertilised with aged manure or burnt, so I suspect the seed might respond to nitrate levels (and wild amaranth are nitrate accumulators I believe). Has anyone experienced the same?
3. Do people have other recommended varieties that they might be interested in swapping? Maybe we could set up a seed exchange like the kenosha potato project. If people want to send seed samples to me I could repackage and split each strain to redistribute a wider variety back to each participant.

[Ryan M Miller]

Answer to original questions:
1. If an amaranth species is monoecious (both male and female flowers on the same plant) as well as self-fertile, then it will be impractical to emasculate the flowers on each plant. You could try using the cytoplasmic male sterility (CMS) trait to control pollination, but this same trait could also reduce potential grain yields. One trick Joseph Lofthouse uses to encourage cross-pollination among self-fertile plants is to plant two or varieties of the same species as close to each other as possible to encourage cross pollination. There will still be a high rate of self-pollination, but the likelihood of a cross-pollination will still be higher than if the two varieties were grown in separate beds or isolated rows.
2. I have noticed similarly inconsistent germination of amaranth seeds when I attempt to sow them in unimproved soil. Many wild species of amaranth are originally native to disturbed river floodplains so they are adapted to the rich soil of riverbanks and agricultural fields. Because amaranth is said to accumulate nitrates in its leaves (according to PFAF), it would not be a good idea to use extra nitrogen fertilizer on amaranth plants.
3. From my experience, I get the highest grain yields by mass and the largest seeds from amaranth cultivars from the species, Amaranthus hypochondriacus. In 2019, I got an estimated yield of 3,607 lbs of seed based on my harvest of 5.3 ounces of seed from 16 plants. I am currently trying to see if I can select wild redroot amaranth (Amaranthus retroflexus) for improved seed production since this plant is such a common weed in my growing region, but I got poor seed yields when I tried to grow it in 2019 at only 2.3 ounces of seed from 32 plants giving only 895 lbs of seed per acre.

[S.Simonsen]

Thanks for that Ryan. I also suspected I would just need to interplant my best varieties and grow out a lot of seed. Hand pollination with bagging and emasculation might be worth doing on a very small scale for wide outcrosses to generate a tiny amount of founding hybrid seed.

Soil that was waterlogged and accumulated organic matter, then dried out allowing the formation of nitrate sounds like an ideal habitat for wild amaranth. I will have to see how I can scale that up in the future. One way I like to grow amaranth is as a gap filler in corn crops. I hand sow the corn, then put a pinch of amaranth on top of each position. That way if the corn fails to grow in any spot the amaranth can grow there instead. I am looking into using a controlled application of heat/fire during my bed preparation and roasting the surface organic matter might be able to reproduce a similar effect.

On the same topic, have you ever considered Celosia spicata as a grain crop? It is incredibly productive and hardy for me. I can find records of the seed being pressed for oil, but the cake being presumably discarded, and whole seed doesnt seem to be eaten. Analysis found a toxic peptide (moroicin, the same one found in the horrible sting of the gympie gympie tree that grows near me) so that might explain it, but that is an injected toxin so it might not be effective when consumed. Because it is perennial I plan on establishing stands where my chickens free range since I often see pigeons feasting on the fallen seed.

[S.Simonsen]

Just an update. I had some self sown seedlings come up through our subtropical winter from a reclaimed Oscar Blanco seed stock that had been in storage for years. That unusual variety showed the non-shattering trait which makes harvest timing easier and the final yield a lot higher than any other strain I have trialled. They also werent as short as I remembered, topping out around 1.2 m.
Among the self sown seedlings is one with a mixture of pink and white flowering heads, while the original strain was all pure white. It might be a hybrid or a just a sport, but it gives me hope that there must be some way to do genetic  mixing and selection on grain amaranth. I will store the mixed colour seed separately and see what I get growing it out.