Q.(a) Explain afforestation with case studies. OR

(a) Afforestation is illustrated by the Chipko Movement and Joint Forest Management; (b) plant tissue culture rests on totipotency, dedifferentiation, and redifferentiation.

(a) Afforestation with case studies

Afforestation is the deliberate establishment of forest/tree cover on land that did not previously carry forest, or that has been deforested, with the aim of restoring green cover, preventing soil erosion and desertification, and providing ecological and economic benefits such as carbon sequestration, wildlife habitat, and sustainable timber/fuelwood supply.

A well-documented Indian case study is the Chipko Movement (originating in Uttarakhand in the 1970s), a grassroots forest-conservation movement in which local villagers, notably women, physically embraced ('hugged') trees to prevent them from being felled by commercial loggers; the movement subsequently promoted large-scale community-led afforestation and forest protection across the region.

Another widely cited case is Social Forestry / Joint Forest Management (JFM), government-and-community partnership programmes under which local communities participate in planting and managing trees on degraded forest land and wastelands across several Indian states -- restoring green cover while also providing the community with fuel, fodder, and small timber, and giving villagers a direct stake in protecting the plantation, which greatly improves the long-term success of the afforestation effort.

(b) Basic concepts involved in plant tissue culture

Plant tissue culture is founded on a small set of key biological concepts:

1. Totipotency: the fundamental property of a living plant cell -- even a fully differentiated, mature one -- to give rise, given suitable conditions, to a complete new plant. This is the theoretical basis that makes tissue culture possible at all.
2. Explant: a small piece of living plant tissue (such as a shoot tip, leaf disc, or nodal segment) that is aseptically excised from the parent plant and used to initiate the culture.
3. Aseptic (sterile) culture technique: the explant, culture vessels, and nutrient medium must all be kept free of microbial contamination, since bacteria or fungi would rapidly overwhelm the slow-growing plant tissue; this requires surface-sterilising the explant and working inside a laminar air-flow cabinet. …