Response of warm-season grasses to N fertilization and salinity

Good knowledge of how growth and physiological traits vary as a function of salt concentration in the soiland different nitrogen fertilization regimes is fundamental for sustainable management of warm–seasongrasses in sport and recreational areas. The research presented in this paper was conducted in a green-house. Plant material was obtained by taking undisturbed soil cores from mature stands. Treatmentsconsisted in combinations of salinity (0, 15, and 30 dS m−1) and N rate (0, 5, and 10 g N m−2). The speciesused were Cynodon dactylon × C. transvaalensis ‘Tifway’ and Zoysia japonica ‘Meyer’ as Chloridoideae, andPaspalum vaginatum ‘Salam’, as Panicoideae. Top growth, expressed as cumulative clipping dry weight(DW) and verdure DW, significantly decreased with increasing salinity. Positive effects of N fertiliza-tion were observed for cumulative clipping DW, although the growth responses were more pronouncedunder non-saline and intermediate salinity conditions. Under the highest salinity, no significant increasewas observed in response to N rate. ‘Salam’ showed a positive response to N fertilization in terms ofroot and horizontal stem (rhizomes and stolons) DW though no such response was observed in ‘Tifway’and ‘Meyer’. The leaf pigment response to salinity varied with the species. All pigments within eachspecies showed similar behavior. In Paspalum, pigment content was not affected by salinity level, thoughchlorophyll a slightly decreased at the highest salinity level.