Re: [CH] self-incompatibility with C. pubescens

Brent Thompson (brent@hplbct.hpl.hp.com)
Wed, 13 Oct 1999 09:06:48 -0700 

> But after the latter flowered like hell with no yield whatsoever I had to
> learn about self-incompatibility in C. pubescens. Too bad!

First off, C. pubescens usually does not exhibit self-incompatibility.
Occasionally, though, some plants are self-incompatible -- it's not rare,
just uncommon; so, you may have just been unlucky.  Better luck next time;
the odds are in your favor.

But, beyond this unlikely possibility, if you look through the chile-heads
archives for the numerous and lengthy past discussions about fertilization
of C. pubescens, you will find discussed many instances of rocoto
reluctance to get fertilized, for any number of minor or unknown
environmental/cultural reasons, by plants that later proved to be perfectly
self-compatible.  It might be worth your time to look through those
archives (though I confess I don't actually know how much time it would
take to find what you want, to reasonably accurately gauge the value of the
exercise).

Of course, the first most important thing is, if you didn't attempt manual
pollenization of your flowering-like-hell rocoto (you didn't specify), then
you must do so before zero yield holds any particular significance.
Sometimes suitable natural vectors just aren't available for rocotos
situated far from their native homes.  At my home, ants are the major
pollenization vector of rocoto (while they're carrying around and
protecting their mealybug, scale, and aphid buddies) -- if I were to
properly control the ants, I imagine I wouldn't have anywhere close to the
well over 300 fruits I've collected so far off my largest rocoto plant this
summer.

If a plant really is self-incompatible, however:

> A) identical twins: suppose an asexual clone (cutting)
> B) fraternal twins: suppose seedlings grown from two seeds 
>                     taken from the same parent pod
> C) siblings       : suppose seedlings grown from two seeds
>                     taken from different pods of the same parent
> D) strangers      : suppose seedlings grown from two seeds 
>                     taken from genetically different parents

then your choices B, C, or D would be necessary (and these three are all
totally equivalent, since each presents pairs with different sets of
genes).

Choice A, two plants grown from cuttings off same plant, genetically ARE
the same plant, hence of course remain self-incompatible if the rootstock
is self-incompatible.
 ---   Brent