summary:Let Gn,k (Gn,k) denote the Grassmann manifold of linear k-spaces (resp. oriented k-spaces) in Rn, dn,k=k(n−k)=dimGn,k and suppose n≥2k. As an easy consequence of the Steenrod obstruction theory, one sees that (dn,k+1)-fold Whitney sum (dn,k+1)ξn,k of the nontrivial line bundle ξn,k over Gn,k always has a nowhere vanishing section. The author deals with the following question: What is the least s (=sn,k) such that the vector bundle sξn,k admits a nowhere vanishing section ? Obviously, sn,k≤dn,k+1, and for the special case in which k=1, it is known that sn,1=dn,1+1. Using results of {\it J. Korba\v{s}} and {\it P. Sankaran} [Proc. Indian Acad. Sci., Math. Sci. 101, No. 2, 111-120 (1991; Zbl 0745.55003)], {\it S. Gitler} and {\it D. Handel} [Topology 7, 39-46 (1968; Zbl 0166.19405)] and the Dai-Lam level of Gn,k with