Question

Richmond Lang effect is due to
A. Cytokinin
B. Auxin
C. ABA
D. All of the above

Answer 1

Hint:-Richmond and Lang were the scientists that discovered this effect in 1967. Cytokinin (regulate cell division, chloroplast differentiation and delay of senescence), Auxin (stimulates the elongation of the stem and restricts the development of lateral buds) and ABA i.e. abscisic acid (control the seed and bud dormancy) are the plant hormone.

Complete Answer:-Cytokinin is a phytohormone that evaluates the degradation of protein synthesis in leaves and the disappearance of chlorophyll. Due to senescence yellowing of leaves occurs and ultimately brings to the drop from the plant. The stimulation of cell division by the Cytokinin phytohormone can delay the plant senescence. This phytohormone likewise prohibits the damage of chlorophyll and accordingly, the parts of the plant do not change into yellow. Hence, this effect is named as a Richmond Lang effect. According to this effect, the lag of senescence of distinct portions and leaves happens with the support of plant development controller Cytokinin. The delay of chlorophyll degradation rate occurs by retarding senescence, the yellowing colour of the leaves and maintaining it effectively longer. Senescence of leaves is a developmental process that energetically begins as part of an age-dependent hereditary procedure or in reactions to environmental pressure which governs apoptosis.

So, the right option is (A) i.e. Cytokinin.

Note:- If a fresh excised leaf is held in water, it slowly alters its colour to yellow and then dies. But if leaves are given with Cytokinin, the yellowing of leaves is considerably delayed and such an effect is known as a Richmond and Langs effect. It possesses an impact on the synthesis of protein and mobilising nutrients.