Physiological disorder in Tomato Fruit

Physiological disorders are abnormalities in fruit color or appearance that are abiotic in origin. These disorders are distinguished from deficiencies of a single nutrient and physical-chemical or herbicide injury. 

Fruit Cracking

Symptoms:

Cracking on the surface of the fruit at the stem end is a common occurrence. It is developed mostly in fully ripe fruit than in mature green or breaker stage.Sudden water availability causes rapid fruit expansion leading to fruit cracking.

 Causes:             

1. High temperature and high light intensity
2. Excessively rapid fruit growth cracking.
3. Some cultivars crack more than other because of genotypic differences.
4. boron deficiency (especially calcareous soil)
5. Fruit exposed to sunlight leads to more concentric cracking.

Management:

1. Soil application Borax @ 15-20 kg/ha.
2. Spraying of borax 0.25% 2-3 times fruiting stage to ripening stage.
3. Maintaining plants at low to medium soil moisture so preferable to grow in the greenhouse.

Blossom end rot (BER)

Symptoms:

The water soaked area near the bottom or blossom end of the fruit. The area usually develops rapidly eventually resulting in a blackened, dry, sunken leathery spot.BER affects the blossom end of the placenta and adjacent locular contents as well as the outer wall. It can most easily be identified by a discolored, sunken spot at the blossom end of the fruit.

Causes:

BER is not caused by any single factor but a combination of one or more factors intensifying the effect it includes high salinity high MgSO4, NH4 and/ or K concentration. Accelerated growth rate, unfavorable moisture relationships.

Management:

• Cultural practices, such as the use of polyethylene mulch maintain adequate soil moisture, and avoiding varieties that are most susceptible to BER will help reduce the incidence.
• Misting or fogging inside the greenhouse reduces the incidence.
• Foliar spray of CaCl2 solution 0.5%@time of fruit developed was an effective control.

Puffiness

Symptoms:

Puffiness refers to the existence of open cavities between the outer walls and the locular content in one or more locules and is also known as hollowness or boxiness.

Causes:

• Nonfertilization of ovules
• Embryo abortion after normal fertilization
• High temperature and high soil moisture are predisposing factors.

Management:

• Maintenance of normal temperature.
• Spraying of Borax or Solubor 10-15 ppm at the peak flowering time.

Sunscald or Sunburn

Symptoms:

Green fruits exposed to direct sunlight ripen unevenly so that yellow patches appear on the side of the tomato fruit when it ripens. Symptoms are most likely to appear at the mature green to breaker stage of development. The lesions are infected by secondary infection of fungus which shows black dark spots making tomatoes units for consumption 

Causes:

• High fruit pericarp temperature 40.C
• In bright sunlight, surface temperature may be more then10 c highest then the air temperature.

Management: 

• The best protection against sunscald is to utilize cultivars with enough foliage to cover the fruit and to provide enough water and pest protection to maintain the healthy foliage
• Crop are planted at higher densities are less susceptible
• Cultivation of indeterminate /semi-determinate varieties without staking

Blotchy Ripening

Symptoms: 

This disorder also known as the gray wall is recognized as grayish appearance caused by partial collapse of the wall tissue hence the term gray wall. The affected area remain green or yellow are usually found nearly at the stem end of the tomato fruit

Causes:

K deficiency

Management:

• Use of balanced fertilizer dose (after soil testing) in the crop prevents the occurrence of blotchy ripening
• Adjust planting date to achieve favorable light intensity for good fruit development.

Cat Face

Symptoms: 

Cat face is a disorder characterized by gross deformity of tomato fruit, which usually renders them unmarketable. The defect is usually located on the blossom end of the fruit cat face is a commonly observed in first harvest.

Causes:

In the field air temperature of 17/10c for a weak are sufficient to induce abnormal flower development Low temperature during the sensitive period increases the no. of locales in the fruit. The time of greatest sensitivity for an individual flower is well before anthesis.

Control:

• Maintenance of sufficient soil moisture balance
• Recommended cultural practices should be adopted

Gold Fleck or Gold Speck

 Symptoms: 

Gold speck or flecks are often observed around the calyx and should of mature fruit particularly in a summer season. In green fruit, the speck is white and less abundant.  The specks decrease the attractiveness of the fruit and significantly shorten its shelf life. Cells containing a granular mass of tiny calcium salt crystals, probably calcium oxalate appears as a golden color.

Causes:

These specks are considered to be symptoms of excess calcium in the fruit. Increasing the P level also increased calcium uptake rate and increased speckling. As temperature increases during the growing season, the incidence of gold spot also increases particularly when average temperatures are higher than usual.

Control:

Cultivars resistant to BER tend to be more susceptible to gold spots. Increasing the electrical conductivity of the nutrient solution reduced the gold speck incidence

By: Lalit Kumar Verma 
B.S. Asati 
Hemant Kumar 
Okesh Chandrakar
Summit Visvas
Sonu Diwakar

Department of Vegetable Science
Pandit Kishori Lal Sukla College of Horticulture &
Research Station Rajnandgaon, (C.G.)
Email: lalitkumarverma@gmail.com