Assertion :During embryo development in dicots, suspensor serves as the main nutritive tissue for the embryo.
Reason :The last cell of the suspensor at the end adjacent to the embryo is known as haustorium.

During embryo development in dicots, the suspensor cell divided transversely a few times to produce a filamentous suspensor of $6-10$ cells. The first cell of suspensor towards the micropylar end becomes swollen and functions as haustorium whereas the last cell of suspensor at the end adjacent to the embryo is known as hypophysis. The function of the suspensor is to anchor the embryo to the embryo sac and push it deep into the endosperm so that the embryo lies in a nutritionally favourable environment.

So, the correct answer is 'Both Assertion and Reason are incorrect'.