PPDL Picture of the Week

April 17, 2017

Seedless fruit production

Wenjing Guan, Assistant Professor, Department of Horticulture and Landscape Architecture, Purdue University, Southwest Purdude Agricutural Center

A plant is considered to be seedless if it is able to produce a fruit either without seed or a much-reduced number of seeds. In some cases, seedless fruit may possess traces of aborted seeds. Seedlessness is a desirable fruit character because seeds are often hard, have a bad taste and produce hormones that lead to fruit deterioration. As a result, seedless fruit often has better quality and longer shelf lives.

Seedless watermelons that were introduced in the 1990s have become the main type of watermelons grown in the U.S.  Besides seedless watermelons, breeders have developed seedless varieties for other fruiting vegetables. This article briefly introduces the different types of seedless fruit and discusses potential opportunities for growing theses varieties.

Seedlessness exists in two forms. In the case of seedless watermelons, the fruit contains partially formed seeds that are aborted after fertilization. Seedless watermelon plants are self-infertile. They must be pollinated by a seeded watermelon plant (diploid) in order to produce a seedless fruit. Another form of seedlessness is called parthenocarpy, for which fruit are seedless because the ovary is able to develop without fertilization, therefore they do not need pollination. The parthenocarpic character can be found in most of the common cucumber types, i.e. picking, slicer, long and mini cucumbers. It also exists in summer squashes. Green zucchinis are more likely to carry the parthenocarpic character; varieties include Partenon, Dunja etc. A yellow summer squash Golden Glory has also been found can set fruit without pollination.

Without the need for pollination, parthenocarpic cucumbers and summer squashes are ideal for high tunnel and greenhouse production. In addition, these varieties work well with insect netting, as the nettings do not need to be removed at flowering stage as required by varieties that need pollination.  Parthenocarpic tomato and eggplant varieties are also available. One of the advantages of growing parthenocarpic tomatoes is that they can set fruit when environmental conditions are undesirable. This is particularly true in the early season that low temperature prevents fertilization.   


Reference:

Producing summer squash without pollination – ranking varieties

Less is better: new approaches for seedless fruit production

These varieties are ideally to grow in high tunnels are where keeping bees in the tunnel is always a challenge. We have seen more growers, especially organic growers start to use row covers to exclude pests. However, these row covers must be removed once female flowers are produced in order to allow for pollination. Parthenocarpic cucumbers and summer squashes

Some varieties of cucumbers and summer squashes are parthenocarpic. They can set fruit without pollination.

Parthenocarpic characters are present in pickling, long and slicer cucumbers, are available in and summer squashes are becoming popular.

However, fertilization is required to produce seedless watermelon. As a matter of fact, grow seedless watermelons require planting pollienier plants nearly. This is because the plants producing seedless watermelons are tetraploid. Because of the imbalance of chromosome number, tetraploid plants are self-infertile. They must be pollinated by a diploid plant in order to produce a seedless watermelon.

One is called parthenocarpic, for which fruit are seedless because the ovary is able to develop without fertilization.

 We understand the way to grow seedless watermelons require planting pollinizer plants nearby. This is because the plants producing seedless watermelons are tetraploid. Because of the imbalance of chromosome number, tetraploid plants are self-infertile. They must be pollinated by a diploid plant in order to produce a seedless watermelon. Seedless watermelons have white seed traces, seeds in the seedless watermelon are aborted after fertilization.

Developing tetraploid is a typical way of producing seedless fruit. In these cases, pollination is required, although development of the seeds disrupted after fertilization. Another form of developing seedless fruit is called parthenocarpy, in which the ovary is able to develop without fertilization.

Seedless watermelon

Seedless cucumber

Seedless zucchini

Seedless tomato

Seedless eggplant

Seedless pepper



Click image to enlarge


 

A seedless watermelon


 

A seedless cucumber