Absence of $Mg^{++}$ ions from plant tissue results in

Grey spots of oat are caused by the deficiency of:

It is observed that the deficiency of a particular element shows its symptoms initially in older leaves and then in younger leaves. Does it indicate that the element is actively mobilized or relatively immobile?

Deficiency of which group of elements can cause inhibition of cell division in plants?

Deficiency of which of the following elements causes the weakening of the pedicel and petiole?

In plants,a common symptom caused by the deficiency of $P, K, Ca$ and $Mg$ is the