Fruit Cracking in Pomegranate

By Hamza Sardar*, Mujahid Ali** (*Horticulture, UOS; **IHS, UAF)

The Prophet (PBUH) said, “There is not a pomegranate which does not have a pip from one of the pomegranates of the Garden (of Jannah) in it” and it is known to Muslims as Qur’anic fruit because it is mentioned in Holy Quran.

Pomegranate (Punica granatum) belongs to family Lythraceae and is one of the most important and major fruit crops of the world. It is native from Iran to the Himalayas in northern India and it is produced at large scale because of its hardy nature, drought resistance, low cost of maintenance, steady yield, good keeping quality and the medicinal value of pomegranate are the main features of its spread at a wide scale. India ranks first in pomegranate production followed by Iran and other producing countries are Turkey, Pakistan, Spain, Italy, China, Japan, France, Spain, Greece, Morocco, and Afghanistan etc. But the excellent pomegranates come from Turkey and Iran. In Pakistan, the total area under pomegranate cultivation is 9434 hectares with annual production of 42641tonnes and Balochistan is a major producer of pomegranate in Pakistan which produces almost 30223 tonnes pomegranates every year.

Pomegranate is a deciduous shrub that grows between 5 and 12m tall. Its branches are multiple and spiny and it is long-lasting plant almost 200 years of age in France. Its leaves are opposite, narrowly oblong, 3-7cm long and 2cm broad. The flower of pomegranate is bright red in color and 3cm in diameter, having three to seven petals. Botanically, pomegranate is considered as berry fruit which is produced from the ovary of single flower and numbers of seeds vary in it from 200 to 1400. It can be propagated by sexual and asexual method but seedlings produced from sexual mean are not true copy of the parent so vegetatively produced by (softwood and hardwood) cuttings but generally hardwood cutting of about 10 inches long is taken from one-year-old wood and planted in polythene bags where it grows for one year and after that it is transplanted in field.

Punica granatum has many uses it can be used in making juices, vinegar, Anar dana, chutney, curry, salad, ice cream, sauces, wine, syrups, mixed with yogurt, jam etc. Fruit has a great nutritional value it contains carbohydrates, sugar, dietary fiber, fat, protein, vitamins, minerals that’s why it has a lot of health benefits like anti-inflammatory effect, helps in fight against cancer, lowers blood pressure, improve blood flow to the heart, fight arthritis and joint pain, improve memory, helps fight against bacterial and fungal infections, reduce risk of heart disease, improve bone health, makes vision better, stimulates immune system and helps against stomach upsets. These are its immense health benefits and uses but there is also a big risk to pomegranate worldwide which is it’s fruit cracking actually it is disorder which lower down its quality and it is a real threat to fruit industry moreover if we want to take benefits from pomegranates in future then we should have to overcome cracking to save this nutritious fruit crop for our future which is discussed below.

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Waiting all year for juicy, fresh pomegranates to mature can be a real killer – much more so when they suddenly start cracking just before harvest. Fruit cracking is a challenging problem of fruit industry and losses due to it are quite high. It is a natural disorder which is reported due to different reasons like:

  • Lack of orchard management
  • Tree age
  • Environmental factors like temperature and rainfall
  • Deficiency of micronutrients like (Boron, Zinc, Manganese, Copper, and Molybdenum) that are involved in physiological processes during fruit growth period and their deficiencies cause cracking
  • Over maturity
  • Pests
  • Pathogens

The previous literature review also describes some efforts for overcome cracking in pomegranates like, In China, in 2009 a study on fruit cracking and the relationship to cultivar, tree age, and cultivation practices in the main pomegranate cultivars in the Yicheng, Zaozhuang, Shandong Province was performed and analyzed statistically. The results showed significant differences in fruit cracking severity between different pomegranate cultivars like the cracking rate of cultivar Daqingptian when bagged was (4.1%) compared to (46%) in the unbagged control.  And it was concluded in this experiment that fruit cracking reduces with bagging and increases with tree age.

In India the cracking of pomegranates is also a serious problem and experiments were performed to control over it like, in 2012 the foliar spray treatments of Boric acid (0.2%, 0.4%), Ferrous Sulphate (0.5%, 1%) and Calcium Chloride (0.5%, 1%) were imposed and data was collected these results were very effective for reducing the percentage of cracking. In this experiment, it was concluded that pre-harvest spray of 0.2% Boric acid resulted in the lowest percentage of cracked fruits (3.33%) followed by (5.51%) in Calcium Chloride and (7.12%) in Ferrous Sulphate.

During (2014-15) in Iran, an experiment was conducted to control cracking in pomegranate by foliar application 2 and 5 ml l-1 humic acid, 6% kaolin and 3% Calcium-1% Boron (CB) during water stress. The results that were obtained are the lowest percentage of fruit cracking is seen with the application of 6% Kaolin and 5ml l-1 in September even though cracking was also reduced with the application of 2 ml l-1 of humic acid with CB and 6% Kaolin. And another important thing that was noticed in this experiment that fruit weight was increased by the application of 6% Kaolin while 5ml l-1 humic acid increases the acidity and decreases the flavor. This experiment gives good results for controlling cracking but none of the treatment provides 100% protection against fruit splitting so additional research is needed to control cracking.

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Environmental factors like (temperature and rainfall) temperature variation are the reason for fruit cracking among day and night. It is believed by some farmers in India that fruit wall is dry during summer and due to increasing temperature and the sun bright during summer and then with decreasing temperature in autumn fruit will be cracked. Rain is also a source of fruit splitting especially when it occurs at the time of ripening because the fruit is becoming soft at this stage and its skin will burst due to the high speed of rain splashes.

Over maturity and is a serious problem of fruit cracking. Fruits should be harvested just before when they will overripe (a little early before over-ripening) to avoid cracking. Many times farmers do not harvest the crop at its proper time due to some reasons like capital or laziness which results in over ripening and ultimately become a source of cracking.

Pests may also contribute to fruit cracking such as whiteflies, thrips, scale, leaf-footed plant bug, and mealybugs. It is reported that leaf-footed plant bug attacks on overripe fruits and crack them. But till today none insect is considered a serious source of cracking however it needs the attention of researchers.

The most dangerous disease of pomegranate is bacterial blight which is a source of the splitting of fruit. It is identified by brown or black spots on different parts of the tree such as stem, leaf, nodes, and fruits. Firstly, these spots appear on stem then leaves and next spread on fruit with cracks passing through black or brown spots.

To conclude as explained above in the past experiments have been conducted to control fruit cracking in pomegranates by different methods but results are not satisfactory and enough to fully overcome cracking so there is an urgent need of conducting more best research on fruit cracking in pomegranates because it is a major fruit crop of world and has much more importance related to human health and economy for the reason that it is grown worldwide at large scale as well as it is risk to fruit industry. In Pakistan, it is still considered as minor fruit crop but we should have to grow this as a major fruit crop because it has immense health benefits and highly nutritious crop in addition to improve the status related to horticulture of Pakistan.

Mujahid Ali

I have recently completed my Ph.D. in Institute of Horticultural Sciences, UAF previously worked as Visiting Lecturer in Horticulture UOS, worked as Research Fellow in ACIAR project on vegetables and worked as Teaching Assitant in Horticulture UAF. Moreover, Ph.D. IRSIP done in the United States.

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