Question

The final stage in the tissue culture program before the new plants are taken out for cultivation in the fields is known as
(a) Micropropagation
(b) Hardening
(c) Caulogenesis
(d) Embryogenesis

Answer 1

Hint: Under monitored conditions like high humidity plantlets are kept for a few weeks before transferring into the soil. These plantlets are grown in netted plastic filled with nutrient medium and suitable conditions.

Complete answer:
Hardening is a practice where healthy/elite plantlets are exposed to the natural conditions in a stepwise manner. The plantlets are transferred to the pots/polythene bag and immediately irrigated with inorganic/nutrient solution. Plants are kept in the hardening room or greenhouse where controlled conditions of light, humidity, and temperature are maintained. Plants are maintained under high humidity for 5- 6 weeks and subsequently transferred in the field so as to grow under natural conditions. The success rate of micropropagation depends on the survival of the plantlets when transferred from culture to the natural environment.
- A collection of methods that are used to maintain or grow plant cells, tissues, or organs under aseptic conditions on a nutrient culture medium either liquid or semi- solid in a state of known composition is called Plant tissue culture.
- Murashige and Skoog medium is a plant growth medium used in laboratories for the cultivation of plant cell culture.
- The tissue obtained from a plant that can be cultured in a nutrient plate under controlled laboratory conditions is called an Explant. In a totipotent, an explant can be collected from any part of the plant.
So, the correct answer is, ‘hardening.’

Note:
Application:
- The commercial production of plants which uses meristem & shoot culture to produce large numbers of identical individuals in laboratories.
- To conserve rare or endangered plant species.
- Tissue culture can be used to screen cells rather than plants for advantageous characters.
Large scale growth of plants in bioreactors in a liquid nutrient medium for the production of valuable compounds.