BOTANY

Detailed explanation-1: -Cytokinins. These are produced in the regions where cell division occurs; mostly in the roots and shoots. They help in the production of new leaves, lateral shoot growth, chloroplasts in leaves etc. They help in overcoming apical dominance and delay ageing of leaves.

Detailed explanation-2: -Ethylene (plant hormone responsible for ripening and senescence), Abscisic acid-ABA (stress hormone), and Auxin (growth hormone) all play a symphony and cause ‘Abscission-falling/separation of leaf tissue’ from the plant.

Detailed explanation-3: -As most developmental processes in plants, the regulation of abscission involves the plant hormone auxin.

Detailed explanation-4: -Auxin is known to exert an inhibitory role on primary root growth. An auxin gradient, established by local auxin biosynthesis and transport, is important for primary root growth. Auxin synthesized in roots via the IPyA pathway is crucial in normal root elongation and root gravitropic responses [43].

Detailed explanation-5: -Important roles in timing of abscission have been assigned to the plant hormones ethylene and auxin. La Rue (1936) showed that removal of the leaf blade induces abscission; but when auxin is applied to the site of removal, abscission is inhibited.