The Tropical Fruit Forum

How do your seedlings and the original fruit compare to this Amalfi Citron from Italy ?
https://agrumilenzi.it/en/negozio/citrusen/citrons/amalfi-citron-citrus-medica/

The leaves of your seedlings look closer to this than Citron leaves ??

Also, the seed in the fruit you uploaded don't really look like Citron seed to me. They seem rather big, more like Sour Orange seed ?

Thinking that the Amalfi Citron is possibly a Citron / Sour Orange hybrid ?

The seedlings look pretty good. The odd one looks pretty interesting. Also looks bit lime like to me. It could depend on if the Amalfi Citron is a 'pure Citron' or a Hybrid. It is possible to get unusual seedlings from genetic re shuffles, without X pollination. ( recombination ). Citrons do not normally produce foliage variants, but I did get slight fruit shape + size variants from seedlings. Lemons seedlings are often slight foliage variants. Can't quite see, but does the odd seedling have red growth tips like other Citrons. ?

Citrus in space
https://www.facebook.com/photo/?fbid=955031949345446&set=a.305197420995572

This came up on my FB feed, I thought it was impressive.

A rare opportunity to see the work of this significant member of the Madrid Realists, Isabella Qunitanilla. Featuring 100 works spanning the artist’s entire career and including her most important paintings and drawings, I'll be travelling to see this one and look forward to sharing more images with you. 'Isabel Quintanilla's Intimate Realism'
Thyssen-Bornemisza National Museum, Madrid. 27 February to 2 June 2024. Pictured: 'Garden' 1966.
https://www.facebook.com/photo/?fbid=894385026022226&set=a.518347880292611

I wen't down the non hazardous / non toxic route for plant pest control. Still noticed minor effects from many " natural " control agents, biological control agents. If you have safety equipment, I would be using it. If a spray tank line nozzle gets blocked or pops off, you can get drenched or hit in the face. It is probably pretty safe, but you don't need canola and pyrethrum in your eye or up your nose. Yes it probably takes longer to suit up than spray, but might be worth the hassle. On of my friends who worked long term in a fried food shop developed a lung disorder from the oil vapour, not uncommon it seems. You won't get that from occasionally spraying, but your being exposed to tiny atomised droplets, which is different to what the rats were tested on. I would go safety where possible.

The scent of Bergamia is pretty distinct. If yours match that scent, it is going to be very similar. If the scent is only somewhat the same ( weaker ), that is another clue.
If your seedlings are either  identical, or quite different that will tell your more.
You could have variable seedlings from self pollination, or from crossing to another Citrus.
Since Bergamia are mainly grown as ornamentals or for perfumery, not edible fruit, you could get something interesting.

Syzygium glenum from the Daintree FNQ, not edible but very rare.....on 17 trees ever found in the wild.rare.....
https://www.facebook.com/photo/?fbid=639499711622660&set=a.619248743647757

There is a big leap from grabbing a few fruit to eat or grow seed, to ripping off trees full of fruit to sell.
Most often I will ask first, and rarely get knocked back. If a tree looks neglected or fruit falling unpicked, I may not ask first.
I must admit to collecting a fair few seed in this way, so find it hard to get too mad when people do the same to me.

“He" that is without sin among you, let him cast the first stone fruit''

Sorry I missed that from your earlier post.
I enjoyed racemosa cluster fig, faint strawberry flavour, like a strawberry cookie. I thought NSW sandpaper figs are nice. If I remember, Deciduous Fig was ok, Moreton Bay was ok, but a few are enough. Not sure any come near Ficus carica in flavour.

"A large clean tree with fruit of fine delicate sweet flavor and size of a black Smyrna fig, only more rounded and dark crimson when ripe."

Interesting that this doesn't clearly ring bells.
Cluster Fig sounds pretty close by size and colour. Flavour is OK too.
Sandpaper Fig seem closer to domestic figs, but I have never seen red fruit, and they are smaller fruited than carica.
Going by the above description, you could eliminate a good 35 to 40 of the 45 Australian Ficus.
That leaves the most likely candidates for you to experiment with.

I believe it is used in the Phillipines as a rootstock, along with Calamandarin. Maybe try researching that. From what I recall, it was used as rootstock for Pummelo.
It should be OK for related things, like Fortunella and Mandarin, maybe Limes ?

Greensand is a rock dust source of Potassium, basically very fine granite dust. You can get it from the places that make cemetery headstones by cutting granite.
Potassium citrate is another source I have seen. Potassium is common in rock minerals, so there should be other sources.