Question

For union between stock and scion in grafting which one is the first to occur

Answer 1

In grafting, cambium bearing shoot (scion) of one plant is joined to cambium bearing stump (root system = stock) of related plant through different union like tongue grafting, wedge grafting, etc. The union of scion and stock leads to irregular, unorganised and undilferentiated mass of actively dividing cells known as callus.