Wow, you'd think some University Ag student or professor would have done some research / written a paper on that by now... But, I, also, searched online and found nothing.*
Unfortunately, by now I'd be running a very uncontrolled experiment, as multiple other factors we've discussed here (thanks to Diana too) are in play: Fertilization (I am quite convinced the Super-Phosphate helped quite a bit, sunlight (seems iffy by now, tho' the plants generally look healthy where not self-shaded, even keeping track of which flowers are from which plant at this point, as some have sort of grown together as I routed the fast growing vines around the supports, and added support, and definitely slight to moderate damage was incurred on some vines as I did that. (A couple bent stalks within 1-4 ft. of the growing tip would be the moderate damage, damaged leaf stems and damaged or cut tendrils would typically be the minor damage.)
Still, I can give a general "report" here. At present, flowering is going well (esp. if most of the female flowers get successfully pollinated). If (IF!) we get 10 or more Opo fruits to 2' or more length by the 1st frost, and the 1st one fully mature in a straight shape** (for seed for next year), I'll consider the project a big success.
Overall plant growth seems unabated. The supports I'd put up (and added to twice) were getting so overgrown / overwhelmed that yesterday I hauled a rusty old ~10' long swing set that we inherited with the property from "way out back" to the garden area. I placed it in an open spot adjoining the tomato garden and about another 10' from the Opo. Then I ran a couple long straight dead branches from the closest Opo support to the top of the swing set, and ran 2 Opo vines a bit onto the branches. A 3rd can be added when it grows a bit more. (As if there's any doubt!) The idea is to head further growth into a sunnier, more open spot, and keep it off the ground. (I can walk or mow under it!) Whether there is time left to get any harvest there is dubious, but, at least part of those plants will be in more sun. This rig looks, well, "hillbilly" engineered in the extreme, but, I don't care at this point. (Funny, isn't it, that I can say that, but not, you know...!)
Also, soon after you suggested the idea of slightly damaging the plants, on maybe 3 of them I bruised / scratched about 1' below a growing tip and~ 1/32" deep, a 2" x 1/4"(?) area of the vine with a fingernail. I no longer can see that damage (the plant healed) and I did not mark / tag the damaged spots, so that trial is even more uncontrolled, now. :-(
That said, I think one of the scratched plants is the one that fired off 4 more male flowers in a group a couple days ago, but in this case those shot up above everything else. Go figure. If they open again tonight I'll take a step ladder out there and attempt hand pollination. I'll likely rig up a LED flashlight*** as earlier mentioned to try to attract more moths.
*The local University has a large AG school with a sizeable Graduate School. Maybe I ought to contact and suggest to the Dean a research paper. (My Dad, who was a Research (and teaching) Forestry Prof there, and did a lot of research on maximizing tree propagation and production, would smile!!) (If only I'd thought to ask him for copies of all those papers!)
**That's something else I learned - yesterday. If the Opo fruit (and, surely, cucumber fruit too) is hanging free and still curved, it was poorly pollinated. So far, the oldest one is now 6" long and growing straight.
***OT: The smaller 5000K Led light on our back porch attracted 3 katydids (that I could reach) last night. I'll fire up the bigger light tonight, too!) Katydids are GREAT bait and the weather tomorrow looks very good to be out. Oh, please let me get enough time...!
Big bummer. The stray Black Lab that “adopted us” some months ago is MIA. 3-1/2 days now. Too long a story to go into now (I’ve been on here too much today already!) But, he had calmed down and was our chickens’ protector. Now we’re gonna have to be doubly diligent...
On the good side of it, once past the Spring tribulations (documented in past threads here), our 12 chicks (1/2 to 3/4 grown pullets, now) are all doing well. The 6 ISA Browns are almost too friendly! So far, no major pullet / older birds problems out in the yard. (They are separated when in the coops, although the older pullets now roost with a rooster - hoping to make them a sort of separate little independent flock.
Will document progress on the waterers, soon. I may even have an idea that would sell commercially, if any small chain might distribute it and not steal it / send the design to China! Unfortunately, I don’t know if patenting it would be worth the trouble. (Getting a patent that will hold up, these days, is a serious & costly undertaking.)
It’s application time for SARE research grants.
I had been trying to think of what project I could use to apply for grant money. D’oh!
Thank you for reminding me. “Using minor bruising to stimulate flowering on plants that are day-length sensitive, as well as common vegetable species in which the specific variety is shy to flower”! That’s perfect!