PH of substrate and seed germination

[ralphrmartin]

One anecdotal data point for you Dave. I once produced my own "Epiphyllum" crosses, and harvested the seed. When I sowed it, nothing happened. I then reasoned that the juicy fruit were mean to pass through a digestive system, and sprinkled some vinegar on the pot, waited a while, and then sprayed the seeds to wash it off somewhat. They came up like cress after that.

[SteveJones]

Hi everybody. I suppose this is a closely related topic I'm about to sow some Uebelmannia seed and am wondering if I need an ericaceous compost as I know that the adult plants prefer an acid substrate or will a seed and cutting compost do?

Steve

[DaveW]

Yes Ralph some seed can depend on being ingested to break down the germination inhibitors. Also some seeds (not cacti) need to be sown in the fruit and not allowed to dry out. I remember reading some years ago Kew could not germinate some conventionally dried plant seeds, therefore as they obviously germinated quite well in habitat they asked for them to be sent still in the rotting fruit and alerted the Customs not to throw away the stinking mass and when sown in the fruit germinated quite freely.

Strange to say Epiphyllum along with some Eriosyce are species that can exhibit endogenous vivipary with the seed germinating whilst still in the fruit.

https://academic.oup.com/jxb/article/58/14/3865/458849

Not sure how many cactus seeds pass through animal or bird guts, but found this one regarding other seeds:-

http://trace.tennessee.edu/cgi/viewcont ... anhonoproj

However it seems acid rain can even inhibit the germination in some seeds:-

http://www.fofweb.com/Electronic_Images ... Fv2-09.pdf

It seems however these things can depend on plant families and be both generic and specific, so one set of pretreatment conditions may improve one species germination, but inhibit another's.

I would think Uebelmannia's would need a compost on the slightly acid side of neutral to let the seedlings grow on when they germinate. Graham Charles always recommends a slightly acid compost for Uebelmannia's and he grew quite a few from seed.

[esp]

It would seem odd if a large proportion of cactus seeds aren't ingested, since the typical cactus fruit seems to involve small seeds in an edble pulp. A vinegar wash may be worth a try for other reluctant germinators..

There do seem to be a huge amount of parameters associated with seed germination, with relatively ad-hoc research available on only a small number of cactus.

As I side issue, I picked a fruit off a Christmas cactus the other day, (from winter 2015, it had been on the plan 2 years) and there were a few viviparous seedlings, this answering my question about whether it had set viable seed.