Question

Explain following terms : (a) Grafting \quad (b) Apomixis \quad (c) Polyembryony \quad (d) Parthenocarpy

Hint:

Remember these terms by their outcome:

\textbf{Grafting:} Two plants become one.
\textbf{Apomixis:} Seeds without sex (clones).
\textbf{Polyembryony:} Many embryos in one seed.
\textbf{Parthenocarpy:} Fruit without seeds.

Answer 1

Plant Reproduction Techniques and Phenomena

1. Grafting: A horticultural technique of asexual propagation where parts of two plants are joined so they grow as one. The upper part (scion) of one plant is placed onto the root system (stock) of another plant. This allows combining desirable traits, such as good fruit quality from the scion and disease resistance from the stock.
2. Apomixis: A type of asexual reproduction in plants that mimics sexual reproduction by producing seeds without fertilization. The embryo develops directly from a diploid cell in the ovule, bypassing meiosis and gamete fusion. The resulting seeds are genetically identical to the parent. Common in grasses and citrus fruits.
3. Polyembryony: The phenomenon of having more than one embryo in a seed, resulting in multiple seedlings. It may occur due to:
   • Formation of multiple embryo sacs within one ovule.
   • Cells of the nucellus or integuments developing into embryos.
4. Parthenocarpy: The development of fruits without fertilization. Since ovules are not fertilized, the resulting fruits are seedless.
   • Natural parthenocarpy: e.g., bananas, some varieties of pineapple and grapes.
   • Artificial induction: achieved using growth hormones such as auxins.