Polynomial Grothendieck properties

A Banach space $E$ has the Grothendieck property if every (linear bounded) operator from $E$ into $c_0$ is weakly compact. It is proved that, for an integer $k>1$, every $k$-homogeneous polynomial from $E$ into $c_0$ is weakly compact if and only if the space ${\cal P}(^kE)$ of scalar valued polynomials on $E$ is reflexive. This is equivalent to the symmetric $k$-fold projective tensor product of $E$ (i.e., the predual of ${\cal P}(^kE)$) having the Grothendieck property. The Grothendieck property of the projective tensor product $E\widehat{\bigotimes}F$ is also characterized. Moreover, the Grothendieck property of $E$ is described in terms of sequences of polynomials. Finally, it is shown that if every operator from $E$ into $c_0$ is completely continuous, then so is every polynomial between these spaces.