Okra

Insect Pollination for Okra

Okra is primarily a southern vegetable garden plant, grown for its immature pods, which are consumed when cooked either alone or in combination with other foods. Hawthorn and Pollard showed 475 acres devoted to seed production in 1951. Miller indicated yields of 1,000 to 1,500 pounds of seed per acre. At a planting rate of 8 pounds of seed per acre, this 475 acres should supply sufficient seed to plant 60,000 to 70,000 acres of okra.

Plant:

Okra is an upright annual, 3 to 6 feet tall, with a main stem and several branches. It is susceptible to frost but can tolerate hot weather and will grow anywhere cotton will grow. It is usually planted in 3- to 3 1/2 foot rows, the plants about 1 foot apart in the row, after all danger of frost is past. The pointed angular, ribbed or round pods, 3 to 5 inches long, are made up of five to nine carpers, each carper capable of producing about 30 seeds. The okra leaf is similar to that of cotton, 4 to 12 inches across. There are numerous cultivars.

Inflorescence:

The single showy okra flower, as much as 2 inches across, resembles the cotton flower, with its wide corolla usually made up of five yellow to cream-colored petals. The erect sexual parts consist of a five to nine part style, each part with a capitate stigma, surrounded by the staminal tube bearing numerous filaments . The flower opens shortly after sunrise and remains open until about noon. The petals wilt in the afternoon and usually fall the following day. The anthers dehisce 15 to 20 minutes after the flower opens, and some of the pollen comes in contact with the stigma.

Pollination Requirements:

The okra pollen grain is large with many pores, and every pore is a potential tube source; therefore, many tubes can develop from one pollen grain. Okra is self-fertile, and, when the anthers come in contact with the stigmas, self- pollination may result; however, cross-pollination also occurs. Purewal and Randhawa reported that 100 percent of both bagged and open flowers set fruit, but they did not indicate the degree of seed setting in the two treatments. They also reported 4 to 18 percent cross-pollination.

If the anthers deposit an adequate number of pollen grains on the stigmas to fertilize all of the ovules, and outside agency is not needed to transfer the pollen. However, if an inadequate amount of pollen contacts the stigmas leading to each carper, and some of the ovules are not fertilized, that area around the unfertilized ovule is less well developed.

Pollinators:

Okra is not wind pollinated. It is freely visited by honey bees and bumble bees, but the value of insect pollinator visitation is unknown. Studies should be made of seed production and pod development of bagged, selved, and cross-pollinated okra flowers to clarify the pollination requirements and needs for pollinators.

Pollination Recommendations and Practices:

None.

Pollination Problems:

  • You can see flowers but have dried up without producing fruit

A Self-pollinating Plant

Self-pollinating plants, like okra, produce flowers that contain both male and female parts and are fertilized by their own pollen. This means they do not require wind or insects to pollinate properly. Other self-pollinating garden vegetables include lettuce, peas, lima beans and bush and pole beans. Problems occur when insects bring in other types of plant pollen, such as other cultivars of okra, leading to cross-pollination.

Concerns of Cross-Pollination

Cross-pollination is not a concern for vegetables of differing species; it is a concern for those of the same species. Cross-pollination does not affect the fruit during the growing season but the seed for next year’s crop. This impacts home gardeners who grow two different okra cultivars and save seeds for the next growing season, as the seeds saved are likely to contain characteristics of both okra varieties.

Preventing Cross Pollination

Since okra is self-pollinating, it produces a decorative bloom that attracts bees and other insects that travel from one bloom to the next, leading to cross pollination. Covering the flowers just before they open with a cloth bag and keeping them covered while in bloom is one method of prevent cross-pollination. Other methods include growing only one species of vegetable or spacing them. The degree of cross-pollination depends on several factors: the insect population, the growing season, the cultivar and competitive vegetation.

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