आम में अत्यधिक ऊतक गलन, इसके कारण और प्रबंधन

Mango the king of fruit occupies approximately 50% of all tropical fruits produced worldwide. Mango is growing in many countries like India, Indonesia, Brazil, China, Egypt, Mexico, Phillipines, Pakistan, Vietnam and Thialand. Mango is nutritionally rich and its pulp contains good dietary fiber, pro-vitamin A, Vitamin C and diverse polyphenols

Further, India share approx. 49.62 per cent of area and nearly 42.06 per cent of world’s mango production. Moreover, mango production in Uttar Pradesh was the highest i.e. 23.85 per cent in country. Various varieties of mango are cultivated in India but Dashehari stood first in terms of choice particularly in U.P.

Dashehari fruit size is medium, shape is elongated with yellow fruit colour. But, the problem of tissue softening (jelly seed) disorder is very high in Dashahari mango (Singh et al., 2006). Several commercially grown mango varieties in India such as ‘Dáshehari’, Langra, Chousa, Bombay green (Singh 2011, Srivastav et al., 2015) or exotic varieties such as ‘Tommy Atkins’, ‘Sensation’, ‘Zill’ and ‘Kent’ (Oosthuyse 1993) are susceptible to jelly-seed disorder.

Among these varieties the incidence of JS (excessive softening of tissue of pulp around the stone) is very high in Dashehari, thus need major attention, and it brought down the export potential of this variety. The shelf life of Dashehari fruits and its firmness decline due to this and leading to poor marketability of produce.

What is Jelly seed in mango ?

Physiological disorders associated with mango (Mangifera indica L.) affect the  producers not only in India even elsewhere in the world. These disorders may cause enormous losses by reducing the quality of the fruits thereby affecting their consumer acceptability.

Among physiological disorders, stem end cavity, jelly seed and soft nose are affecting the mango fruits and they have been described to affect different parts of the fruit (Raymond et al., 1998). Jelly-seed was first described by Van Lelyveld and Smith (1979) who described that in this disorder, there is a breakdown of mesocarp in the area surrounding the seed (stone). The affected portion develops off-flavour and may become dis-coloured in later stages.  

So, Jelly seed in simple term can be defined as the excessive softening of pulp around the seed of mango fruit.  The disorder occurs at the interface between the stone and the pulp of the fruit with no external symptoms except the appearance of a jelly like mass around the seed of the affected fruit. Therefore, fruits that have been affected by jelly seed can only be recognised so when cut. So, non-destructive methods are required for detection of jelly seed.

Figure: Incidence of Jelly seed formation in Dashehari mango

Possible causes of Jelly seed formation ?

The fruit of mango being a living tissue is continuously changes until it process of deterioration completed. In mango fruits the programmed changes like ripening process that influence the appearance of fruits, their flavour, texture and nutritive value. But when the fruit was damaged, all of the biological processes within the fruit, like respiration and ethylene production proceed at a rapid rate leading to rapid deterioration.

The maximum incidence of JS was noticed in the fruits that harvested after second week of June or after. Further, the incidence was higher in tree ripened fruits as compared to artificially ripened fruits (Dwivedi et al., 2021).

Srivastav et al. (2015) reported, the exact cause of this disorder is not known but it is considered to be cultivar dependent and varies widely in the naturally and/or artificially ripened mango fruits. Although, Seshadri et al. (2016) showed, that JS in ‘Amrapali’ mango arose at the start of germination-associated events in the seed of developing fruit.

Premature seed germination reduced synthesis of very-long-chain fatty acids (VLCFAs) in the seed promoted the production of cytokinins onset of premature germination-associated events in the seed. Consequently, a large increase in the activities of pectinolytic enzymes in JS pulp, rapid degradation of pectin and excessive softening of the pulp, to the consistency of jelly.

Moreover, during fruit senescence, the soluble calcium in the fruit decreases and the fruit cell wall degrades, resulting in physiological disorder metabolism of the fruit and consequently fruit decay and deterioration (Gao et al., 2019).

Localized calcium deficiencies can cause leaky membranes, irregular cell wall softening, impaired hormonal signalling and aberrant fruit development. Deficiency of Ca leads to destabilization of pectic matrix thus cell wall loosening and depressed cell cohesion.

Calcium is mainly absorbed from the root system; but, only a small portion of calcium can be transported to the actual fruit. The low phloem mobility of Ca²⁺ can also lead to calcium deficiencies in fruit.

Possible Management of jelly seed :

Various chemical treatment have been proposed by researcher, in order to mitigate this new burning problem in mango. Among these solutions, Calcium application got maximum attention because  Ca⁺ ion play important role in membrane stability via link between Ca and phosphate group of phospholipid and carboxyl group of protein on the surface of membrane, and cell integrity.

Calcium treatment could effectively maintain fruit firmness and delay fruit softening and ripening and also reduce the accessibility of cell wall degrading enzymes, reinforcing the cell wall structure by cross linking pectic acid residues.

• Application of Calcium chloride (2.0 %) at three stages of fruit development (fruit set, 30 days after fruit set and 30 days to anticipated physiological maturity) was more effective in reducing jelly seed occurrence (Bitange et al., 2020)
• Formulation (NaCl₂, KCl, H₃BO₃, CuSO₄, ZnSO₄, FeSO₄, MnSO₄, and EDTA) can be used for correcting the JS disorder in Amarpali mango (Seshadri et al., 2019).
• Application of black polythene mulch (100 micron) to cover soil around tree and application of 2% dihydrate calcium chloride at second week of may (Singh, V.K. 2017) was found very effective.
• Harvesting of fruit on time can reduce Jelly seed incidence.

Future line of  research:

One of the major challenge is that to develop the non-destructive method in order to quantify the disorder. Secondly, identification of the possible causes of Jelly seed formation with their known biochemical and molecular mechanism. Further, to develop best management practices for the mitigation of this physiological disorder, in order to get better fruit quality and market price.

References:

• Bitange, N., Cheminingwa, N., Ambuko, J., Owino W. (2020). Can calcium sprays alleviate jelly seed in mango fruits? Journal of Agriculture and Rural Development in the Tropics and Subtropics. 121, 35–42.
• Dwivedi, S.K., Ahmad, I, Mishra, D, Gupta, A, Kumar, D and Singh V.K. (2021) Jelly seed formation in mango, possible causes and its management. Abstract in Abstract book, Page No. 141, National Conference of Plant Physiology, ISPP.
• Gao, Q., Tan, Q., Song, Z., Chen, W., Li, X., Zhu, X. (2020). Calcium chloride postharvest treatment delays the ripening and softening of papaya fruit. J. Food Process. Preserv.  https://doi.org/10.1111/jfpp.14604 e14604.
• Oosthuyse, S.A. 1993. Effect of spray application of KN0₃, urea and growth regulators on the yield of Tommy Atkins mango. SA. Mango Growers' Assoc. Yearbook 13:58-62.
• Raymond, L., Schaer, B., Brecht, K.J., Jonathan, H., Crane, J.H. (1998). Internal breakdown in mango fruit: Symptomology and histology of jelly seed, soft nose and stem-end cavity. Postharvest Biology and Technology, 13, 59–70.
• Seshadri, S., Manoharan, S., Singh, H.S. (2019). Preventive regulation of jelly seed disorder in Amrapali mango (Mangifera indica L) by pre harvest spray. Horticultural Plant Journal, 5 (2), 70–78.
• Sheshadari, S., Sumathi M., Singh H.S. (2016). Premature seed germination induced by very-long-chain fatty acids causes jelly-seed disorder in the mango (Mangifera indica L.) cultivar ‘Amrapali’ in India. J Hortic Sci Biotechol 91(2):138–147
• Singh, V.K. (2017). Aam mey galan (Jelly seed) samasya aur uska prabandhan. Udhyan Rashmi, Oct- 2017 - March 2018.
• Singh, V.K., Kumari, S. (2011). Changes in biochemical and mineral constituents associated with jelly-seed in mango (Mangifera indica L.) cv. Dashehari. Ind J Agric Sci 81(6):563–566.
• Singh, V.K., Singh, D.K., Pathak, S.M. (2006). Relationship of leaf and fruit transpiration rates to the incidence of softening of tissue in mango (Mangifera indica L.) cultivars. American Journal of Plant Physiology, 1 (1), 28– 33.
• Srivastav, M., Singh S., Ajang, M. (2015). Evaluation of mango genotypes for jelly-seed disorder. Ind J Hortic 72(3):408–410.
• Van Lelyveld, L.J., Smith, J.H.E. (1979) Physiological factors in the maturation and ripening of mango (Mangifera indica L.) fruit in relation to the jelly-seed physiological disorder. J Hortic Sci 54(4):283–287

Authors:

Dr. S.K. Dwivedi

ICAR-Central Institute for Sub-tropical Horticulture, Lucknow

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