Relationship between contents of chlorophyll (a+b) (SPAD values) and nitrogen of some temperate grasses

In a field experiment the chlorophyll (a+b) (SPAD readings) and nitrogen contents of three grass species (Festuca arundinacea Schreb., Lolium perenne L., and Lolium multiflorum Lam.) and three intergeneric hybrids of Festuca pratensis Huds. x Lolium multiflorum Lam. and Festuca arundinacea Schreb. x Lolium multiflorum Lam. were measured. Close relationships were found between SPAD readings and nitrogen leaf content (r(2) = 0.873** 0.491** and 0.938**) for the 1(st), 2(nd), and 3(rd) cut, respectively. SPAD readings and N contents were closely correlated (r = 0.836**) confirming that SPAD measurements could be used in grass selection and/or breeding for high N concentration in herbage.