Which hormone is helpful in the regulation of xylem differentiation and also in cell division?

Cytokinin was first synthesized by:

Which phytohormone is useful for the formation of interfascicular cambium during the secondary growth of plants?

Who coined the term 'Kinetin'?

Which phytohormone is useful for delaying senescence?

An excised leaf does not turn yellow if it is induced to root. This is attributed to the synthesis of which hormone in the root,or which hormone retards leaf aging?