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  Morphology


Ikisan - Morphology of Mango

Description of Mango

The Tree and its Flowers

  • The mango tree is believed to have evolved as a canopy layer species in the tropical rainforest of south and southeast Asia.
  • Mature specimens can attain a height of 30m and can survive for more than 100 years.
  • The root system consists of a long, vigorous taproot and abundant surface feeder roots.
  • The tree is an arborescent evergreen tree with simple, alternate, oblong ovate to oblong lanceolate leaves that are spirally arranged and produced in flushes.
  • Its flowers are borne on terminal pyramidal panicles, glabrous or pubescent; the inflorescence is rigid and erect and is widely branched, usually densely flowered with hundreds of small flowers, 5-10 mm in diameter.
  • The flowers are small, monoecious and polygamous.
  • Both male and perfect flowers are found within a single inflorescence the pistil aborts in male flowers.
  • The ratio of male to perfect flowers is strongly influenced by environmental and cultural factors.
  • The flowers have four to five petals that are oblong to ovoid to lanceolate and also thinly pubescent.
  • The floral disc is four to five lobed, fleshy and large, and located above the base of the petals.
  • There are five large, fleshy and large, and located above the base of the petals.
  • There are five large, fleshy nectaries that form a five-lobed receptacle.
  • Although there are four to five stamens, only one or two of them are fertile; the remainder is sterile staminodes that are surmounted by a small gland.
  • In addition, two to three smaller filaments arise from the lobes of the nectaries.
  • The stamens are central.
  • It is believed that the flowers are cross-pollinated by flies.

The Fruit

  • The mango fruit is a large, fleshy drupe, containing edible mesocarp of varying thickness.
  • It is resinous and highly variable with respect to shape and size. Chlorophyll, carotenes, anthocyanins and xanthophylls are all present in the fruit, although chlorophyll disappears during ripening, whereas anthocyanins and carotenoids increase with maturity.
  • Fruit colour at maturity is genotype-dependent. Fruit of 'Bombay Green' is green; 'Carabao', 'Manila', 'Mulgoa' and 'Arumanis' are greenish-yellow; 'Dashehari' and 'Alphonso' are yellow and 'Haden', 'Keitt' and 'Tommy Atkins' have a striking red blush.
  • The exocarp is thick and glandular.
  • The mesocarp can be fibrous or fibre-free with favour ranging from turpentine to sweet.
  • The endocarp is woody, thick and fibrous.

The Seeds and Polyembryony

  • The seed of mango is solitary, large and flat, ovoid oblong, and is surrounded by the fibrous endocarp at maturity.
  • The testa is thin and papery.
  • The seeds are not labyrinthine. Seeds of monoembryonic mango types contain a single zygotic embryo, whose cotyledons can be unequal and lobed.
  • The seeds of polyembryonic mango cultivars contain one or more embryos are derived directly from the nucellus, a material tissue.
  • Nucellar embryos apparently lack a suspensor. Polyembryony has also been reported in M.casturi, M.laurina and M.odorata.
  • Occasionally, a single embryo is found within a seed of a polyembryonic cultivar; however, it may or may not be a zygotic embryo.
  • Certain polyembryonic cultivars reportedly can produce seeds with adventitous nucellar embryos only, e.g. 'Strawberry', 'Carabao' and 'Pico' and 'Olour' and 'Cambodiana'.
  • It is believed that polyembryony is a polygenic trait and segregates as a recessive character in the progeny of controlled crosses.
  • Seedlings can be distinguished from the single zygotic seedling from polyembryonic seeds by means of isozyme analysis.
  • Mango seeds are considered to be recalcitrant, and cannot survive for more than a few days or weeks in storage at ambient temperatures.
  • This important characteristic of mango seeds would have prevented their long distance dispersal until recent times.

 
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