Coconut

Abnormalities

Poly Embryony Horned Nuts Abnormal Leaves Suckering Male Coconut Female Coconut Branching Variation in Number of Carpels

Poly Embryony


Polyembryony

  • Although the coconut palms are remarkably uniform in their morphological features, a number of abnormalities in respect of the tree, flower and fruit have been met with.


Abnormalities in the vegetative parts

  • A nut on germination may give rise to one and sometimes to two or three shoots, each through a separate' eye '.
  • But in rare cases, more than one shoot is seen emerging through a single eye. This phenomenon is called poly-embryony.
  • Each 'eye' represents a carpel which is one-ovuled.
  • Normally, one carpel with a developed ovule is capable of producing only a single shoot.
  • In few cases of poly-embryony, a nut produced three distinct shoots emerging through the' soft eye.
  • The two other' eyes' were closed and were as hard as those in an ordinary nut where the two carpels are abortive.
  • There was only one cavity in the endosperm into which three haustoria developed, and there were neither hard nor leathery dissepiments in it.
  • The kernel inside also showed no signs of any special connection with the closed eye as it showed with the' soft eye '.

Top

Horned Nuts

  • Coconut fruits bearing flat horns usually ranging from one to six are a rare phenomenon.
  • Development of the staminodes, duplication of the gynaecial segments, apocarpic nature of the ovary and hypertrophy of the perianth parts are often attributed to be the causes for the production of horns in coconut.
  • This horn was due to the abnormal development of one side of the papery ring, the growth of the other half of the ring having become arrested at an early stage so that it was not visible when the perianth was still attached to the nut.
  • The horns are formed as a result of duplication of segments of gynoecium.
  • Often, one or two or even all the three carpels of the additional whorl develop into big horns.
  • When the horn was cut open and was found to be full of fibrous tissues only.
  • Some floral modifications, wherein the periarith parts of certain flowers have developed into thick horn like structures.
  • The portion of the flower which usually develops into the gynoecium was foliated into a small " bulbil-shoot " in these interesting flowers.

Top

Abnormal Leaves


Abnormal leaves

  • The monocot leaf is said to be the expanded petiole of an ordinary leaf, the lamina portion having been lost in the course of evolution.
  • The lamina portion of a palm leaf, that is the' fan' or' feather-limb and it is not the morphological lamina, but only a modification of the distal region of the true petiole.
  • Leaflets are formed in a coconut leaf as a result of the primary division of the original petiole.


Twin leaves

  • Abnormalities in leaves are less common than in other parts of the palm. The more common among these are instances of forked leaves, twin leaves, fused leaves, multi-leaf, etc.
  • These variations are brought about by various causes. Certain abnormalities on trees advanced in age where leaflets are fused and do not separate as in ordinary palms. This is brought about by a genetic factor or factors.

Albinism

  • In coconut nurseries, a few albino seedlings with complete white or yellowish leaves are sometimes noticed.
  • The albinos are less than 0.1 per cent of the total number of seedlings. These do not respond to manurial treatments.
  • Albinism is most probably due to certain genetic factors brought together by cross pollination.
  • And in some cases albinism in coconut seedlings is due to' some internal factor and chlorosis due to lack of ferruginous products in the endosperm. Such seedlings have been observed to be devoid of chloroplasts and generally die after producing 4 to 6 leaves.

Top

Suckering


Suckering

  • Branching in palms restricted to the underground portion of the stem (bole) or when it happens at the ground level is termed' suckering '.
  • These branches usually emanate from the nodes that are buried in the soil.
  • These suckers, though weak, looked quite normal and resembled the ordinary young palms.
  • One of these suckers on replanting, established itself and commenced flowering, but did not produce suckers.
  • Suckering in coconut is an economically interesting phenomenon in the breeding of the coconut palms.

Top

Male Coconut

Abnormalities In Sex Expression

  • Normally, the coconut palm is monoecious, bearing male and female flowers in the same inflorescence.
  • Occasionally, however, it has been observed to express unisexual condition which is possibly a stage in evolution.
  • A few male coconut palms which produced only male flowers. These were otherwise quite similar to the ordinary tall variety of coconut.
  • The male inflorescence is more robust and has numerous spikes and very many male flowers.
  • These flowers are larger in size than those of the ordinary palm. The spadices of these trees showed branched spikes and often produced secondary spadices.
  • Invariably such an inflorescence has numerous spathes or highly developed bracts.
  • The inflorescence of a male tree has a greater number of male flowers per bunch than in the ordinary palm.
  • These palms although of no economic value, may prove useful for the tapping of toddy.

Top

Female Coconut

  • Instances of female coconut palms, which flowered within a year of transplanting. Such palms have been designated as Midget palms.
  • These palms bearing the terminal inflorescence died soon after producing the first inflorescence.
  • The inflorescence was conspicuous for the absence of the spathe.
  • However, two bracts developing just below the corymbose inflorescence took the place of the spathe.
  • The gynoecium of the flowers is very interesting as it comprises only of tree carpels. One of its flowers had only two carpels.
  • Some abnormal female flowers of coconut, where the three carpels were fused only at the base, being free to a greater or lesser extent at the apex.
  • Another factor which is common to most of these peculiar seedlings, except the one is that they are progenies of the dwarf variety.

Top

Branching


Abnormal branching

  • Branching is a rare phenomenon in the coconut palm.
  • It is also of considerable importance as it provides a means for securing increased yields with less planting space.
  • Branching in coconut may take place at all stages of growth and from the various regions of the stem.
  • Branching in coconut has been attributed to the following causes.
  • When the growing point of a young palm is injured, there is a tendency for the bole to throw out adventitious buds because of the meristematic activity of the ground tissues of the bole.

  • Branching is also induced consequent on the injury of the terminal bud by rhinoceros beetle, lightning and by diseases, fire, storm, etc.
  • Branched palms are usually unproductive, but a large number of instances branched palms bear normally.

Top

Variation In The Number Of Carpels


Abnormal nuts

  • Normally, a female flower has three united carpels each having an embryonic ovule.
  • Some times coconut plant also produce a bicarpellate coconut fruit and tetracarpic fruit.
  • The epicarp of bicarpellate fruit had only two ridges and two stigmatic lobes.

  • The endocarp of the fruit has only two ridges and each carpel is indicated by a separate' eye '.
  • Some flowers of the midget palm also produced only two carpels.In tetracarpic fruit, the four carpels are clearly represented by the four' eyes " the four distinct ridges on the endocarp and the tetragonous nature of the epicarp.
  • The four stigmatic lobes which persist till the maturity of the fruit are also indicative of the four carpels. As usual, the fruit is only one-seeded.
  • Here the biggest' eye' is' fertile , or' soft '.

Top

Telangana