Stenospermocarpy

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Stenospermocarpy is the biological mechanism that produces seedlessness in some fruits, notably many table grapes. Normal pollination and fertilization are required to set fruit in stenospermocarpic fruits. The near seedless condition results from subsequent abortion of the embryo that began growing following fertilization. The remains of the undeveloped seed are visible in the fruit.

The fruit of seedless grapes is smaller than normal because the seeds produce the plant hormone gibberellin, which causes fruit enlargement. Most commercial seedless grapes are sprayed with gibberellin to increase the size of the fruit and also to make the fruit clusters less tightly packed. A new cultivar, 'Melissa', has naturally larger fruit so does not require gibberellin sprays.[1]

Grape breeders have developed some new seedless grape cultivars by using the embryo rescue technique.[2] Before the tiny embryo aborts, it is removed from the developing fruit and grown in tissue culture until it large enough to survive on its own. Embryo rescue allows the crossing of two seedless grape cultivars.

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[edit] Seedless grape cultivars

Seedless grapes are divided into white, red and black types based roughly on fruit color. The most popular seedless grape is known in the United States as 'Thompson Seedless', but was originally known as 'Sultana'. It is believed to be of ancient origin. It is considered a white grape, but is actually a pale green. Other white cultivars are 'Perlette', 'Menindee Seedless', 'Interlaken', 'Himrod', 'Romulanus', 'Lakemont', 'Fayez', and 'Remailey Seedless.' The most popular red seedless in the U.S. is 'Flame Seedless'. Other red cultivars are 'Crimson Seedless', 'Ruby Seedless', 'Suffolk Red', 'Saturn' and 'Pink Reliance'. Some black cultivars are 'Black Beauty', 'Black Monukka', 'Concord Seedless', 'Glenora' and 'Thomcord.'

[edit] References

  1. ^ Ramming, D.W. 1999. New grape trio. Agricultural Research 47(10): 23. [1]
  2. ^ Wood, M. 1997. Mouth-watering new fruits Agricultural Research 45(8): 9-10.[2]

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