If you look inside a seedless grape you�re likely to find a couple of tiny soft seeds. A seed is actually the embryo of a new plant, but in seedless grapes the embryos stop growing before they are fully formed.
Youcan trick a plant into producing fruit without seeds by pollinating the plant with pollen that isn�t entirely compatible. Although fertilisation occurs, the cell division needed to produce the new seed stops after a short time. However, the fruit surrounding it carries on developing.
The plant can also be fooled into thinking fertilisation has occurred by spraying it with the hormone, gibberellic acid. Gibberellic acid is normally produced by the seeds to make the fruit develop, so spraying with the hormone means the fruit can develop without the need for the seeds.
To encourage big juicy grapes, growers place a jacket of steam around the plant to kill the cells that transport the sugars and hormones down the plant to the root. This leads to a build up of sugars and hormones at the top of the plant with nowhere to go but into the fruit. The grapes use this bounty to swell and grow.
There remains one problem of course. How do you get a new plant from these grapes, if they don�t have any seeds? Easy - take cuttings and grow these into new plants.
From the food technology website.
Kind of puts one off grapes ever so slightly !!!