Flower And Fruit Manipulation

Fruit Manipulation

Fruit manipulation in crops is usually limited to fruit thinning or synchronisation of fruit drops or fruit ripening.

Fruit thinning is done to remove fruit that is diseased, malformed or has poor colour development. Fruit is also removed from young tree crops to ensure that the tree is not damaged due to too high fruit loads. In some cases, reduced fruit loads will reduce the number of fruit borne per tree, but will lead to an increase in the quality of the remaining fruit.

Where diseased leaves have been removed in the case of crops such as hydroponics tomatoes, the fruit is removed, to ensure sufficient leaf development for the following crop. Fruit thinning can be done by hand, as in the case of tunnel produced vegetables, or maybe done using chemicals in the case of tree crops.

The process of fruit ripening can be encouraged using chemicals. A compound for example such as Ethephon can be used to induce even ripening in tree crops. In crops such as macadamia and walnuts, the compound is used to ensure even nut drops, making the harvest easier.

In some crops such as blueberries and cherries, bud break will only occur after the crops have experienced significant cold spells. Should insufficient cold be experienced, the crop will not bud and low yields will be experienced. To this end chemicals such as HCN are used to induce bud break.

Pollination is important for fruit set in all fruiting crops. In most cases, bees are the preferred pollinators. Where natural bee populations are low, beekeepers are employed to supply hives to orchards. Where bees are important for pollination it must be ensured that spray programmes are developed to ensure the bee populations are not damaged through pesticide applications.

In the case of hydroponic crops, most pollination occurs through ventilation, insects or the movement of workers through the glasshouses. In crops such as peppers, pollination is critical and manual pollination may be necessary. Vibrating the stay wires on the trellising shakes the plant which aids pollination.

Chemical Manipulation Of Flowers And Fruit

Several chemicals are used to control flower and fruit development in fruiting plants. Through the use of chemicals, the energy of the plant can be directed to the purpose of producing a quality fruit of the required size at the required time.

Through the use of chemicals, you can avoid the period of bud dormancy and stimulate the plant into early production, thus gaining the lucrative early market for a crop.

Chemicals such as ‘Paclobutrasol can control the height of the plant, terminal buds can be ‘pinched’, cold requirements substituted, and excessive long shoots can be chemically disbudded.

Ethylene is a chemical that is naturally produced in fruits, seeds, flowers, stems, leaves and roots and controls a multitude of processes.

Ethylene is used commercially to promote flower development and colour formation and speeds up fruit ripening. Ethylene is also used in the production of pineapples to stimulate even flowering.

Click here to view that explains how Ethylene can be used for fruit ripening.

In deciduous fruit production, the flowers often drop prematurely before pollination has taken place resulting in a loss of potential crop. If the plant is sprayed with the chemical silver thiosulfate, which prolongs flower life and reduces floret abscission.

In apple trees where different shoots types tend to produce different plant parts. Lateral shoots tend to produce vegetative growth. If these are left unchecked the plant becomes very leafy and bears very little fruit. If laterals are pruned, they produce sprigs that carry fruit. Manual pruning of laterals is time-consuming. Chemical pruning will kill terminal buds and produce side shoots that tend to become sprigs that will produce fruit.

Physical Manipulation Of Fruit And Flowers In Crop Production

Physical manipulation encompasses the manual activities that encourage the healthy development of the tree, ensuring that a tree produces regular, acceptable sized fruit when it is wanted. The manipulation directs the plant’s energy into the process of producing a quality fruit within a time period that is expected by the farmer or market.

Thinning

• Thinning is a manipulation process by which a part of a too heavy crop is removed. This leads to improved fruit size and promotes regular cropping by alleviation of alternate bearing.
• Thinning should be carried out early in the season after the first natural fruit shed and as soon as it becomes obvious that the crop will be too heavy. After thinning make sure that mature fruit is not in contact with each other.
• If fruit trees are allowed to produce a too heavy crop, the tree will produce a crop only every second year (alternate bearing). Thinning will ensure that the tree produces a crop every year.
• Thinning can also be done during pruning by thinning out bearer shoots. In tomatoes and cucumbers grown under protection, thinning implies the removal of all lateral branches, leaving one bearing stem only.

Click here to view a video that explains crop thinning.