Question

What is Richmond- Lang effect?

Answer 1

Hint: Cytokinins have many positive effects on the growth of plants. One of such effects is delay of senescence in leaves by mobilising nutrients. Richmond and Lang discovered this effect in 1967.

Complete Answer:
- Cytokinins are one of the five most important Plant Growth Regulators (PGRs). Cytokinins are called Anti-ageing hormones as most of their effects on plants delay ageing and promote growth, directly or indirectly.
- One of the major effects of cytokinins is delaying senescence or ageing of intact leaves and other organs. Here, what cytokinins do is that they control the protein synthesis and increase mobilisation of nutrients in phloem to the ageing parts.
- As a result of increased nutrient access, new chloroplast synthesis, delay of chlorophyll degradation rate takes place in leaves. Thus, the aging process is delayed. This effect was 1st discovered by scientists Richmond and Lang in 1967. Thus, called Richmond-Lang effect.
- There are many applications of Richmond-Lang effect caused by Cytokinins. For example, use of cytokinins for increasing shelf life of vegetables and flowers.

Additional Information:
-Cytokinins play an important role in production of new leaves and shoots, Countering apical dominance, increasing cell division.
Some other applications of Cytokinins include-
- Use in Tissue culture for inducing cell division and differentiation in undifferentiated mass of cells (callus).
- Increasing the size of fruits.
- Promoting femaleness in plants.
-Out of the five PGRs Auxins, Gibberellins and Cytokinins have positive effects on plant growth. Whereas Ethylene and Abscisic Acid have most effects which negatively regulate plant growth.

Note: Richmond-Lang effect is delaying senescence and promoting youth in leaves and other parts of plants by cytokinins. Therefore , Cytokinins are called as Anti-aging hormones for its ageing delaying effects. They increase mobilisation of nutrients to promote growth and cell division.