Introduction
- For incorporation of good colour to boost export of fresh fruits, a number of mango varieties were introduced from different countries for use as donor parent. Tommy, Ziulete, Haden, Sensation and Julie are the coloured varieties of mango which were introduced from Miami, Florida (USA). Other varieties, Pl 24927, M 4336 (Carabao) from USA and EC 201556 (Carabao) from Phillippines were introduced as regular bearing varieties, Cultivar Amolie and Sweet were introduced from Belgium and Thailand respectively.
Selection
- Almost all the present commercial varieties of mango in the world were developed from open pollinated seedling selection e.g. Dashehari, Langra, S.B.Chausa, Rataul, Swarnarekha etc.
- The evolution of Florida varieties which are the leading mango cultivars of the world is interesting. In 1889, introductions were made from India of which Mulgoa became popular. Cultivar Haden was a seedling of Mulgoa. Subsequently, many promising seedlings were selected which became popular. Tommy Atkins from Haden, Keitt from Mulgoa, Dyke and Palmer from unknown origin, Irwin from Lippins, Golden Nuggets and Brooks from Sandersha, Sensation from unknown origin etc. are promising seedling selections.
Clonal selection
- Exploitation of natural variability for selection of superior clones of commercial mango cultivars has been undertaken. Clonal selection has also resulted in identification of few elite clones. Dashehari-51 from Dashehari, a regular bearer (CISH, Lucknow), ‘ Subash’, a chance seedling from Zardalu (BAC, Sabour), Red blush, a strain of Alphonso (Vengurla), heavy yielding strains of Langra and Himsagar (Kalyani, W.B.), bacterial black spot resistant clones of Kensington, superior clones of Rumani and Neelum (Tamil Nadu) and a regular bearing cultivar ‘Cardoz Mankhurad’ in Maharashtra which is selected from Goa Mankurad.
- In Maharashtra, one off-season selection ‘Niranjan” has been made at Parbhani, which comes to flowering during June to July and matures the fruits in October. In TNAU (Regional Research Station, Paiyur), a clonal selection from Neelum was identified as dwarf variety and released as Paiyur-1. This is suitable for high density planting (400 plants/ha).
Hybridization
- In mango hybridization, work taken up in post independence period laid emphasis on regular and precocious bearing, dwarfness, high percentage of pulp, fibreless flesh, large fruits with red blush, good keeping quality and freedom from spongy tissue. In recent years, emphasis has also been laid on evolving varieties tolerant to mango malformation. A variety Bhadauran, tolerant to this disorder, was developed through hybridization between Neelum and Dashehari (Singh et al., 1985).
- The work at Sabour yielded two promising hybrids namely Mahmud Bahar and Prabha Shankar from the parental combinations of Bombai x Kalapady. Hybrid Mahmud Bahar was found to be a regular bearer for four years whereas Prabha Shankar, was not a regular bearer. Further, the work on improvement of mango was initiated at Saharanpur in 1951 and also in Punjab in 1950 to develop regular bearing varieties.
- Later on, in India, nearly 20 inter-varietal hybrids of mango have been released for cultivation from IARI, New Delhi, CISH, Lucknow, IIHR, Bangalore, FRS, Sangareddy, HC & RI, Periyakulam, AES, Paria (Gujarat), FRS, Vengurla etc. Of the hybrids developed in India, Mallika and Ratna have received commercial recognition. The cultivar ‘Sindhu’ evolved through intensive back crossing between Ratna and Alphonso develops fruits parthenocarpically under natural temperature conditions.
Interspecific hybridization
- Interspecific hybridization did not receive more attention but it can be a useful tool to transfer some useful genes in cultivated varieties. This is possible because all the Mangifera species have the same chromosome number (2n = 40). Therefore, they can inter cross easily (Mukherjee, 1963).
Improved Hybridization technique
- Single day pollination of limited number of flowers in a panicle is the ideal practice. Here, the main emphasis was given on utilizing large number of panicles and crossing whatever few flowers opened on the panicle during that single day. Bagging with perforated polythene bags of 24" x 12"size of 100 gauge was preferred. Crossing of a few flowers in a given panicle at one time is advocated than taking up crossing in more number of flowers in a given panicle in batches over a number of days. (Mukherjee et al., 1961).
- Caging technique: The discovery of self incompatibility in some of the popular cultivars at IARI, New Delhi led to further improvement in the technique of hybridization. It is known as caging technique (Sharma and Singh, 1970, Singh et al., 1962). In this technique, grafted plants of parent varieties are enclosed in an insect proof cage and pollination is effected through freshly reared houseflies.
- Marker gene: The purple colour of new leaves and panicle and beak characters of fruit helps in identifying the hybrid seedlings in the nursery (Sharma and Majumder et al., 1985).In Israel, a new cultivar, Naomi, has been released which has smooth skin and red pigmentation. In Australia, a hybrid of Sensation x Kensington has shown promising results. In Israel, rootstock breeding is also in progress and a polyembryonic rootstock 13/1 has been released that is tolerant to salinity.
- A new off- season crossing technique was suggested by kulkarni (1986). It involves induction of flowering in the desired parents in off season by veneer grafting, their defoliated shoots on to leafy shoots off season flowering cv Royal special and allowing open pollination between the desired parents. As no other cultivar flowers during this season, this is a safe technique.
Mutation breeding
- Naturally occurring useful mutants like Rosica has been isolated from the Peruvian variety ‘Rasado de lca’. Similarly, Davis Haden is a mutant of Haden. However, no induced mutant is known to have been released.
Polyploidy breeding
- Much scope exists for polyploidy breeding. However, till date there is no report on this line. Vellai Columban cultivar of mango is tetraploid in nature (2n = 4x = 80) which is a polyembryonic type.
Heterosis
- Iyer and Subramanyam (1984) observed large fruits in some progenies of Alphonso x Banganapalli. Transgressive segregation for this character was also observed. The population with bigger fruits was large among hybrid progenies obtained with Banganapalli as one of the parents. This effect may be due to an accumulation of dominant allele each having additive effects and masking the effect of deleterious recessive allele.
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