North American Fruit Explorers mailing list at ibiblio

["Lon J. Rombough" <lonrom@hevanet.com>]

Title: Re: [NAFEX]  pears set fruit without pollen

The misshapen apple, as you note, has seeds on one side.   The embryo of the seed produces hormones that cause the ovary in the vicinity to grow, so the apple or pear is larger on that side, smaller on the side with no seeds, making the fruit lopsided.  But with NO seeds, the fruit is generally normal shape, just small since there are no seeds producing hormones to stimulate the growth of the ovarian tissue.  Same thing in other fruits.  There is a mutation of the old grape Emperor called "Jelly Bean" because it regularly aborts the seed on one side, making the berry misshapen with a sort of "jelly bean" shape.   
    Probably a treatment with hormone such as gibberellic acid would make a seedless apple get as large as a seeded one.
=Lon Rombough
>

> It is my experience that a misshapen apple usually has unfertilized seeds in the area of the depression.  Apples of the proper shape have all of their seeds pollinated..  If a pome fruit was seedless, wouldn't it be misshapen all over, and not a full sized fruit?
>
> It would seem to be a function of nature not to put a lot of plant resources into a fruit, or portion of a fruit, where the seeds are not pollinated (let the runts die off).  I have no explanation for seedless oranges, other than if it wasn't for man, they would have died out too.
>
> My guess would be that a fertilized seed gives off hormones in the growing fruit, that stimulates fruit flesh development around it.  An unfertilized seed  would not inspire fruit flesh growth and the fruit would be misshapen (or abort).
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