Looking into Cucumis crosses, I learned a way to break down crossing barriers I had never heard of–growing the seed parent in a pot. Seems to me this probably be more relevant in the Cucurbitaceae as they naturally want to spread. I’m guessing the pot stresses them which makes them less picky about pollen donors.
“Crosses between C. metuliferus and C. zeyheri 2x succeeded well if the maternal plants were grown in containers of 10 or 25 1 instead of in open soil. This treatment also improved crossability in the cross C. metuliferus x C. melo. It strongly enhanced the number of female flowers per plant in C. metuliferus.”
Would be interesting to take a look the full study.
Thanks for sharing this. I am contemplating working on interspecies crosses of C. metuliferus soon and this was just what I needed. Growing in pots could have so many potential impacts it is hard to guess what the “cause” is. Just a good reminder that compatibility between species is not a black and white situation at all.
I found the full paper on scihub so PM me if you want a copy.
Shane, that would be really great to get more diversity into C. metuliferus. I was thinking about trying the white round kiwano this year. Never grown kiwano before, but have tasted the fruit from the store which I wasn’t crazy about. I heard if you grow them yourself and pick them at the right stage they’re better than the store ones. I would love to see that paper I’ll pm you.
Its a good point about a single cause, there are so many developmental changes that alter crossing ability, definitely not black and white. I mean, even the relationship between genotyp and phenotype is just way more wide open with possibilities than most people realize.
I ran into that paper looking into wide crossing the burr gherkin, since like kiwano its a very strong and resilient species. Next season I’m going to grow (edible) Cucumis ficifolius and cross it with a spineless burr gherkin, to try to get the long 6 month fruit storage quality into the burr gherkin, and provide even extra vigor and disease resistance. Regarding kiwano, I read that while most of the kiwano x melon crosses were done with kiwano as the seed parent, one was done successfully with a wild melon as the seed parent which was also the only F1 not to have needed embryo culture.
There at least five native Cucumis species here in Australia. I wonder if anyone has tried domesticating any of them. The fruits tend to be small, about the size of a round grape, and quite unpleasant on the tongue so there’d be a fair bit of work involved I imagine.
On the subject of kiwano crossing, it looks like C. metuliferus can make viable F1s using C. africanus pollen. Its worth noting that less bitter forms of africanus and zeyheri as used as food. I might see if I can cross it with C. ficifolius or anguria, but these are less likely to succeed.