Parthenogenesis and parthenocarpy
When the egg cell remains unfertilized and develops into a normal embryo, it is called parthenogenesis. Parthenogenesis is of two types.
In haploid parthenogenesis, the haploid female gamete or even the haploid male gamete develops into an embryo.
In many plants, the megaspore mother cell does not undergo meiotic division and forms diploid embryosac. As a result, the egg is always diploid. Such diploid and unfertilized egg divides parthenogenetically and produces normal diploid embryo. This embryo is devoid of a set of genes from the male parent. This type of parthenogenesis is known as diploid parthenogenesis.
Parthenogenesis can be induced in the following ways :
(1) Exposing the mature flowers to high or very low temperature after pollination.
(2) Exposing the flowers to x-ray during meiosis.
(3) By injecting certain chemical substances into the ovaries.
The phenomenon of producing seedless fruits without fertilization is known as parthenocarpy.
Parthenocarpy can be induced in many ways. In some cases mutation or hybridization brings about parthenocarpy. Application of auxin and gibberellin, pollinating the stigmas with foreign pollengrains and treating the stigmas with the extract of the pollen are some other methods by which parthenocarpy can be induced. Indole butyric acid is the most suitable chemical to bring about parthenocarpic fruits of natural size.
Parthenocarpy is useful in producing seedless fruits and help in enrichment of nutrients.