आम के शारीरिक विकार: कारण और उसका प्रबंधन

Many physiological disorders in fruit affect both quality and storage life of mango in all growing regions. In mango a number of factors are responsible for mango yield decline, yet physiological disorders play more devastating and vital role. As a result, mango growers are losing their faith and interest in mango orchards and trying to shift their cultivation practices from mango to other crops.

In this article we discussed the important physiological disorders along with their possible management strategies which will certainly help the farmers in timely overcoming this malady for getting satisfactory remunerative prices from mango cultivation.

Physiological disorder any kind of abnormality in economically important part of fruits or other parts that contribute to yield and quality of fruits is termed as physiological disorder.

Cause of physiological disorders-

• Deficiency of micronutrient
• Sudden fluctuation in temperature
• Poor soil conditions
• Improper moisture availability during cultivation.

Physiological disorders of mango:

Alternate Bearing:

• Alternate bearing is a very serious and an old problem in mango.
• It is the production of a heavy crop in one year or very little crop in the next year.
• South Indian cultivars are regular in bearing.
• Alternate bearer in North India cultivars are specifically Langra, Chausa,

Causes:-

• Varietal differences.
• Growth habit.
• Crop load.
• Cultural practices.
• Sex ratio.
• Insect-pest and disease.

Measure:-

• Use an ethylene releasing compound, ethephon inducing flowers every year.
• The concentration of ethephon 200ppm coupled with 0.1% urea was found effective in inducing regular flowering over the year.
• Application of Paclobutrazol @ 10 g a.i. for non- bearing trees during first fortnight of September will induce flowering and fruit set yield during off years.
• Application of Paclobutrazol @ 5 gm/tree in tree basins can be helpful in checking alternate bearing.
• Pachlobutrazol should be applied 3-4 months before actual flowering takes place.
• Growing of regular bearing cultivar like “Amrapali”.

Mango Malformation:

There are two types of mango malformation:

• Vegetative malformation is more prevalent in the nurseries (Seedling plants).
• Floral malformation

Causes:-

• Fungi- Fusarium moniliformae subglutinans is highly associated with this disorder.
• Temperature range of 21-27⁰C (maximum) and 8⁰C (minimum) along with relative humidity of 85% during late winter or early spring is conducive for the growth of the fungi, resulting severe incidence of malformation on newly emerged panicles

Measure:-

• Spray 200 ppm of NAA twice, i.e. in first week of October and then first week of November.
• Spray of 400 ppm Ethephon at bud inception stage

Jhumka or Clustering

It is characterized by setting of more number of marble- sized fruitlets at the tip of the panicle. The fruitlets remain dark-green in colour. Their shape resembles that of unfertilized fruits. These fruitlets remain attached to the panicle without increasing in size. Such fruits do not grow beyond pea or marble stage and drop down after a month of fruit set.

Causes:-

• Failure of pollination and fertilization due to weather or insecticide spray at full bloom.
• Absence of sufficient population of pollinators in the orchards.
• Competition of new flush for photosynthates with the developing fruits.
• Indiscriminate spray of pesticides during flowering.
• Adverse climate during February-March particularly the low temperature.

Measure:-

• 100 ppm NAA sprays during October and November shall take care of inflorescence development.
• No insecticide spray should be given at the full bloom stage. Jaggery (‘Gur’) @ 10 percent can be sprayed at full bloom stage to attract pollinizers.
• Spraying of pesticides during flowering should be avoided.
• In old orchards, a few branches should be top worked with pollinizing varieties like Bombey Green,
• Introduction of beehives in the orchards during flowering season for increasing the number of pollinators.

Spongy Tissue:

It is a physiological disorder which usually affects Alphonso cultivar of mango. Cheema and Dhani was first to observe spongy tissues in mango in 1934. Which is characterized by the development of non-edible, sour, yellowish and sponge like patch with or without air pocket in the mesocarp of the fruit during ripening. North Indian cultivars are not prone to this disorder. In extreme cases, the whole fleshy portion becomes too soft resembling bacterial rot. Externally fruits appear normal only on cutting the fruit the disorder is detected. The affected fruits give bad odour and are not consumed.

Causes:-

• This is caused because ripening enzymes during fruit maturation stage become inactive due to high temperature, convective heat
• Post harvest exposure of fruit to sunlight

Measure:-

• Harvesting of fruits at 3/4th maturity stage
• Post harvest exposure to low temperatures between 10-150C for 10-18 hrs
• Use of black poly-ethylene mulch
• Grow resistant varieties like Ratna, Arka Puneet and Arka Aruna etc
• By adopting sod culture in orchards or growing legumes as cover crops or adopting mulching of basins and keeping soil moisture near field capacity during fruit development reduces the incidence of spongy tissue development in mango fruits.

Black Tip:

It is a physiological disorder caused by toxic gasses emitted by brick-kiln chimney. It is a serious problem in orchards located near brick-kiln. At first there develop a small etiolated area at the distal end of the fruit, which increases to cover the whole of the tip. Then it turns black. Infected fruits ripen prematurely and drop early. The affected fruit drop pre maturity. Dashehari is the highly susceptible one, while Lucknow Safeda is the least.

Causes:-

• This disorder has mainly detected in orchards located in the vicinity of brick kilns.
• Gases like carbon dioxide, sulphur dioxide and ethylene constituting the fumes of brick kiln, damage growing tip of fruits and give rise to the symptoms of black tip.

Measure:-

• Establishment of the orchards away from brick kiln by at least 1.6 km in east to west and 0.8 km in north to south direction and increasing the chimney height to at least 15- 18 metres can be preventive measures for this malady.
• Spray 0.6% Borax thrice, before flowering, during flowering and then after fruit set.
• Bordeaux mixture 2:2:250 should be sprayed at pea size and repeated after 20 days till fruit maturity.

Fruit Drop

Fruit drop is one the major problems contributing to low fruit yield and is the chief reason for economic losses in all mango-growing countries.

Causes:-

Several factors influence fruit drop, including

• Lack ofpollination,
• Self-incompatibility,
• Failure of fertilization, embryo abortion,
• Nutrient deficiency, water deficit stress,
• Competition between developing fruitlets leading to embryo/seed abortion in genetically
• Weaker sinks,
• Unfavorable climatic conditions (strong winds, hailstorms),
• Incidence of diseases (powdery mildew, anthracnose), andpests (mealy bugs, hoppers)

Measure:-

• Treatment of half mature fruit with NAA or 2,4-D at concentrations ranging from 20 to 50 mg L-¹
• Treatment with auxins in combination with urea or nutrient mixture (KNO3, micronutrient complex) has also been recommended
• Among commercial cultivars, ‘Langra’ is more susceptible to fruit drop, whereas ‘Dashehari’ is the least

Authors:

Ankit Kumar Pandey¹, Sakshi Shastri², Deepak Maurya³, Ram Niwas⁴ and Kuldeep¹

¹Department of Fruit & Fruit Technology, Bihar Agricultural University, Sabour, Bhagalpur 813210 (Bihar)

²Department of Agricultural Extension, Indira Gandhi Krishi Vishwavidyalaya, Raipur, C. G, India,-492 001

³Department of Horticulture (Vegetable & Floriculture), Bihar Agricultural University, Sabour, Bhagalpur, Bihar, India 813 210

⁴Department of Plant Pathology, Bihar Agricultural University, Sabour, Bhagalpur, Bihar 813 210, India

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