Stenospermocarpy is the biological mechanism that produces
parthenocarpy
In botany and horticulture, parthenocarpy is the natural or artificially induced production of fruit without fertilisation of ovules, which makes the fruit seedless. Stenospermocarpy may also produce apparently seedless fruit, but the seeds are ac ...
(seedlessness) in some fruits, notably many
table grapes
Table grapes are grapes intended for consumption while fresh, as opposed to grapes grown for wine production, juice production, or for drying into raisins.
''Vitis vinifera'' table grapes can be in the form of either seeded or non-seeded varieta ...
.
In stenospermocarpic fruits, normal
pollination
Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents can be animals such as insects, birds ...
and
fertilization
Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Proce ...
are still required to ensure that the fruit 'sets', i.e. continues to develop on the plant; however subsequent abortion of the
embryo
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
that began growing following fertilization leads to a near seedless condition. The remains of the undeveloped seed are visible in the fruit.
Most commercial seedless grapes are sprayed with
gibberellin
Gibberellins (GAs) are plant hormones that regulate various developmental processes, including stem elongation, germination, dormancy, flowering, flower development, and leaf and fruit senescence. GAs are one of the longest-known classes of p ...
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.
Grape breeders have developed some new seedless grape
cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...
s by using the embryo rescue technique.
Wood, M. 1997. Mouth-watering new fruits ''Agricultural Research'' 45(8): 9-10.
/ref> Before the tiny embryo aborts, it is removed from the developing fruit and grown in tissue culture
Tissue culture is the growth of tissues or cells in an artificial medium separate from the parent organism. This technique is also called micropropagation. This is typically facilitated via use of a liquid, semi-solid, or solid growth medium, su ...
until it is large enough to survive on its own. Embryo rescue allows the crossing of two seedless grape cultivars.
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
The sultana is a "white" (pale green), oval seedless grape variety also called the sultanina, Thompson Seedless (United States), Lady de Coverly (England), and oval-fruited Kishmish (Iraq, Iran, Israel, Palestine, Pakistan, Afghanistan, India) ...
', 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 'Remaily 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.'
See also
* List of grape varieties
This list of grape varieties includes cultivated grapes, whether used for wine, or eating as a table grape, fresh or dried (raisin, currant, sultana). For a complete list of all grape species including those unimportant to agriculture, see Viti ...
* Seedless fruit
A seedless fruit is a fruit developed to possess no mature seeds. Since eating seedless fruits is generally easier and more convenient, they are considered commercially valuable.
Most commercially produced seedless fruits have been developed from ...
References
{{reflist, 30em
External links
Herrera, E. 2002. Improving size and quality of seedless grapes. Guide H-311. New Mexico State University
Plant reproduction