Our Community Sweetcorn Landrace Initiative Season 1:
36 participants in 4 Australian states: NSW, QLD, VIC & SA
9 Varieties of sweetcorn, some from commercial suppliers, some from seed saving groups. Sourced from 13 locations that were selected to be as diverse as possible. We obtained seeds adapted to subtropical, warm temperate and cool temperate climates and from soils that ranged from high clay/poorly drained through to rich, well-drained soils.
All the seeds were brought to a small gathering of the some participants, each was weighed and counted so we could obtain test weights. We made up 50 packets each containing 149 kernels, each packet an exact replica, because we counted out an even number of all the donor kernels and distributed them equally.
Some participants received more than one packet and some received replacements when they experienced a total loss of their crop. Most participants grew the whole packet, some one;y grew half followed by the other half some weeks later.
Mixed results!!
I’m curious to know what’s going on and would greatly appreciate some help explaining what we’re seeing?
Poor pollination - we each had plants flowering at wildly different times and growing to very different heights before flowering. 50cm right through to 220cm! The poor pollination was not a surprise, we could see it happening with the out of time flowering!
Contamination with Non-Sweetcorn- We have a large amount of individual kernels presenting with no shrivelling when dry, we suspect one or more of the seed donors was carrying non-sweet genetics. These we intend to manually select out & hope that a season or two continuing to do so may easily eliminate them- any advice most welcome:)
Some kernels have a whitish look the them - we’ve no idea why?
There appear to be many malformed kernels, bulbous shapes and erratic growth expressions. I’m curious whether it’s just poor pollination or could there be other contributing factors.
We’d love to know more if anyone has any wisdom of this subject to share!
Warmly, Ian Epic Earth
www.thegourmetgarden.school
Hello and welcome @TheGourmetGardener .
Getting some non-sweet kernels suggests to me that there were both sugary and supersweet types in the mix. Is that a possibility or did you ensure only one type of sweet corn was used?
Edit: I checked out the two corns I didn’t know on your list - Who Gets Kissed and Daughter of the Sun.
The first is a sugary enhanced corn that will blend well with all the other corns on the list, except Daughter of the Sun. Although it doesn’t specifically call it a supersweet its description fits a supersweet and that would explain the occasional non-shrinking kernels you’re finding. If it were me, I’d scrap that corn and work with the others. Mixing sugary and supersweet isn’t a great idea for amateur breeders.
To carry on from here, I would ensure no more Daughter of the Sun is planted and continue to eliminate the non-shrinking kernels. All the other corns should get along just fine.
PS I’m in NSW too, just west of Armidale, attempting to reveg 16 bare hectares and growing as much of my own food as I can reasonably manage.
Hello Ray, thanks for your comment! I’m in Bellingen, not far from you! Your project sounds very interesting! And BIG!! . Thanks for your suggestions. Interesting!! Please excuse my lack of breeding knowledge, so why would crossing sugary and superset varieties result in a carbohydrate profile that doesn’t shrink? So am I gathering that these hard kernels could literally because of the superset DoTS inclusion and not some rogue flour corn genetics that I originally assumed? I’m feeling the same as you suggest about selecting them out! You’re most welcome to some of our seeds if you’d like?
Hello Ian,
There are two genes that either of which in their fully recessive form result in sweet corn. These are the sugary gene and the shrunken gene. Each corn plant has two copies of every gene and both copies of either gene must be the recessive form to result in sweet corn.
A straight sugary corn, the majority in your list of cultivars, has two copies of the recessive form of the sugary gene but dominant forms of the shrunken gene. The supersweet Daughter of the Sun has two copies of the recessive form of the shrunken gene but probably has dominant forms of the sugary gene. Since the offspring of any cross inherits one copy of each gene from each parent when a sugary and a supersweet cross the offspring will get one dominant form of each of the genes in question and the result is a non-shrinking kernel.
Thanks for the offer of seeds but I’m developing a landrace of polenta type corn so I would prefer not to include the sweet varieties.
I recommend that the shrunken gene be eliminated from the genepool. It produces very weak kernels that struggle to germinate when grown in organic conditions. I also recommend eliminating synergistic, since it contains shrunken.
As already mentioned, the shrunken gene (sh2) and the sugary (su) gene are on different chromosomes, so if they cross, then you get a flour/flint corn.
The sugary enhanced gene (se) works in cooperation with the su gene to add extra sugar to a kernel. Kernels that are homozygous for su and se also tend to germinate poorly, therefore for organic production, I recommend growing only sugary (se) corn. Or in special cases, su pollinated by homozygous su/se as an F1 hybrid only. In that case, the homozygous su/se pollen donor may need to be started in a greenhouse, and transplanted out after germination.
And then in subsequent years, cull the entire cob of anything that has about 50% flour/dent kernels on it. And cull any flour/dent kernels on cobs with predominantly sweet kernels.
Now that sh2 has been introduced, it can’t be eliminated by selection alone, without meticulous selfing, and planting out of sibling groups, to figure out which groups contain the sh2 gene. But the prevalence can be greatly reduced by selection-only from mass pollinated plantings.
An alternate culling technique would be to plant these out, and detassel them. Then pollinate them with pure su or su/se lines, and then cull any cobs with flour kernels. Tassels are sneaky, and some always tend to escape notice, so it’s not perfect, but it could help a lot.
what do the milky kernels indicate about their genetics, Joseph?
I’ve just harvested 5 kilos of AD, and 3 kg of my diversity mix that might have some in it.
gm
Thanks Ray, I appreciate your succinct explanation for what may have happened here. I feel disappointed that I’ve blindly stumbled into this complexity so early as it’s thrown me/us a significant challenge just when our fledgling group of enthusiasts could probably have benefitted from an easy win! An interesting exercise nevertheless… Thanks for sharing your knowledge
Thanks Joseph, I really appreciate your guidance here! I see we’re in for a long journey to eliminate the shrunken gene from our pool. What a challenge to be dealing with for complete novices! This is certainly a big hurdle for our group of fledgling enthusiasts and I can’t help but see it as a sort of selection process for our group! Oh the irony!!
Thanks for circling the milky kernels- this picture was of the original grex, so it’s clear we had several milky kernels right from the start. Like Gregg, I’m curious what the milkiness indicates and why they might be a problem/worth removing?
Yeah fair enough. So you didn’t eat any this year? I’m wondering if when the corn is picked they might not be noticeably different in flavour or texture in amongst a mouthful of the normal glassy kernels?
Brill thanks Joseph, I didn’t realise I did start with any dent corn, is that what you’re thinking the milky/opaque kernels that your circled might have been? I grew a crop of Jolly Roger sweet last year and they had an opaque look to the kernels, but shrivelled well, just like we’d expect for a sweetcorn. I’m still undecided whether to continue working with this mix and select for the glassy, shrivelled kernels + work at removing the flour corn arising from the sh2 inclusion, or whether to put this down to experience and start over… There’s a group of us too, so I’ll present my new understanding of our situation to them and leave it up to them to individually decide too. Thanks for your help with this:)
I found photos of seeds called “Jolly Roger Sweet Corn”. Looks like a dent corn to me, not a sweet corn. Some dent corns can be eaten as corn on the cob, but they are definitely not sweet, and their tenderness flits away in a moment.
I munched on the tops of a few cobs just to check for sweetness, but i was mostly focused on seed increase. And i agree, i doubt you would notice a few different kernels unless there was some really weird taste or texture.
WOW, thanks, that’s really interesting!! That’s exactly what I noticed, but having been sold it as a sweetcorn I had no idea!!! I’m in the UK at the mo, but am eager to take a closer look at the JR seeds I have left over. What a journey
thank you everybody for this interesting conversation. I have been reading you since the beginning and learned a lot ! I just decided I am going to have a second look at my jar of sweet corn seeds before sowing.
. Thanks for your suggestions. Interesting!! Please excuse my lack of breeding knowledge, so why would crossing sugary and superset varieties result in a carbohydrate profile that doesn’t shrink? So am I gathering that these hard kernels could literally because of the superset DoTS inclusion and not some rogue flour corn genetics that I originally assumed? I’m feeling the same as you suggest about selecting them out! You’re most welcome to some of our seeds if you’d like? 
