The effect of a graft transformation on distance signless Laplacian spectral radius of the graphs

Suppose that the vertex set of a connected graph G is $$V(G)=\{v_1,\ldots ,v_n\}$$ . Then we denote by $$Tr_{G}(v_i)$$ the sum of distances between $$v_i$$ and all other vertices of G. Let Tr(G) be the $$n\times n$$ diagonal matrix with its (i, i)-entry equal to $$Tr_{G}(v_{i})$$ and D(G) be the distance matrix of G. Then $$Q_{D}(G)=Tr(G)+D(G)$$ is the distance signless Laplacian matrix of G. The largest eigenvalues of $$Q_D(G)$$ is called distance signless Laplacian spectral radius of G. In this paper we give some graft transformations on distance signless Laplacian spectral radius of the graphs and use them to characterize the graphs with the minimum and maximal distance signless Laplacian spectral radius among non-starlike and non-caterpillar trees.