What causes deformed eggplant fruits? How to prevent and control them

During eggplant production, it is common to see eggplant fruits that are curved, cracked, or hard as stone. The causes are mainly influenced by variety, plant vigor, environmental factors, and cultivation techniques.

 

Research indicates that the minimum temperature for eggplant pollen germination and pollen tube elongation is below 15 to 17°C; below 15°C, germination does not occur at all. Even at 15 to 17°C, germination is markedly poor and pollen tube elongation is also poor. However, at temperatures above 35°C, the eggplant flower organs develop poorly. It can be seen that the optimal growth temperature during the fruiting period of eggplant is 25 to 30°C. The eggplant fruit develops from the ovary and belongs to the berry type.

 

From flowering to fruit maturity, the eggplant fruit goes through several morphological stages. During the ripening process of eggplant, the morphological changes of the eggplant fruit are the most obvious. The various morphological stages are as follows:

 

1.

Flowering stage: the corolla spreads flat, the anthers are exposed outside the corolla, the anther sacs split open, and pollen is dispersed onto the stigma.

2.

Petal-wilting stage: the flower bud droops, and the petals wither and fall.

3.

"Eye-opening" stage: the ovary emerges from the calyx, the rudimentary fruit begins to appear, and the fruit skin at the flower end begins to color.

4.

Technical maturity stage: the fruit's volume increase has basically ended, and the skin near the calyx shows little or no further whitening. This is the critical morphological stage for harvesting the fruit for consumption and for the seeds entering vigorous growth.

5.

Physiological maturity stage: the fruit skin ages, the seeds mature, and the fruit is no longer suitable for consumption.

After understanding the morphological structure of the eggplant fruit, it is not difficult to understand the causes of poor fruit production from the fruit's development process. After pollination, the ovary of the eggplant begins to expand and gradually form the fruit. After the corolla falls off, the sepals remain and gradually enlarge as the fruit develops. The expansion rate of the young fruit is clearly greater than that of the sepals. When the young fruit protrudes beyond the sepals, the eggplant fruit at this stage begins to enter a critical indicator of the rapid expansion period. This is also the period when the main flesh cells expand and intercellular spaces increase. At this stage, attention should be paid to a sufficient supply of fertilizer and water to meet the needs of fruit growth and development. If too many fruits are set at this time, causing the eggplant fruits to compete with one another for nutrients, it is very easy for the fruits to develop slowly or unevenly, resulting in curvature. If at this stage there is also a lack of water or an insufficient nutrient supply, the fruit often stops developing, the skin becomes rough, the flesh is relatively hard, the taste is bitter, and "stiff fruits" may also form. However, under low or high temperatures, excessive nitrogen fertilizer application, or excessive irrigation, the growing point receives too much nutrition, so that in addition to meeting the needs of growth and development, a large amount of surplus nutrients remains. This instead causes flower bud differentiation and development to be insufficient, and because nutrient excess promotes overly vigorous cell division, fruits with multiple carpels form, or the stamens partially develop into fringed fruits.

 

In a survey of whether eggplant farmers in the central region use plant growth regulators, most eggplant cultivation in the central region does not use such growth regulators, because during the eggplant harvest period in the central region, except for July and August when fruit set is poor under higher temperatures, fruit set and development during the rest of the production period can reach ideal targets, so eggplant farmers do not use plant growth regulators. Therefore, as long as eggplant seedlings are managed properly, plant vigor is monitored during cultivation, vegetative growth and reproductive growth are balanced, excessive fruit set and damage from diseases and pests are avoided, and it is recommended to adopt a V-shaped pruning method, it is believed that the occurrence of deformed fruits can be reduced.

 

Note:

Curved eggplant fruit:

Refers to eggplant fruit that is curved and cannot straighten.

 

Cracked eggplant:

This refers to the calyx or fruit surface of the eggplant fruit splitting open, so it can be divided into calyx cracking and fruit cracking.

 

Calyx cracking:

Mostly caused by too high a concentration of growth regulators.

 

Fruit cracking:

This is caused by damage to young fruits by the southern yellow thrips, or by the fruit surface being scratched by branches and leaves, causing fruit skin growth to stall, or by the fruit encountering drought and then sudden rain during growth. Either calyx cracking or fruit cracking may cause the fruit to split open.

 

Stiff fruit:

The fruit is relatively small, the skin is rough, the flesh is hard, and there are no seeds or only a few seeds, with no edible value. The main cause is fruit set without pollination, and flowers at the late harvest stage are especially likely to set fruit parthenocarpically.