46. While experimentation, why do you think it is difficult to assign any affect seen to any single hormone?
Phytohormones are synthesised by plant cells, itself and individually. These are auxin, GA, ABA ethylene and cytokinin. There is not a seperate system of their translocation in plants. So, their effects on plants are also inter mixed, e.g., many effects of auxins GA shows the same function. Similarly, ethylene and ABA support each other for many roles in plants.
Secondly, effects of phytohomone in vitro and in vivo will also be different.