Response of warm–season grasses to N fertilization and salinity

• A greenhouse experiment was carried out, under three salinity and three N regimes.
• We identified morphological differences between three C4 perennial turfgrass species.
• Salinity tolerance was strongly enhanced by N fertilization in Paspalum.
• Changes in pigments and proline accumulation were evaluated.

Good knowledge of how growth and physiological traits vary as a function of salt concentration in the soil and different nitrogen fertilization regimes is fundamental for sustainable management of warm–season grasses in sport and recreational areas. The research presented in this paper was conducted in a greenhouse. Plant material was obtained by taking undisturbed soil cores from mature stands. Treatments consisted in combinations of salinity (0, 15, and 30 dS m−1) and N rate (0, 5, and 10 g N m−2). The species used were Cynodon dactylon × C. transvaalensis ‘Tifway’ and Zoysia japonica ‘Meyer’ as Chloridoideae, and Paspalum 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 fertilization were observed for cumulative clipping DW, although the growth responses were more pronounced under non-saline and intermediate salinity conditions. Under the highest salinity, no significant increase was observed in response to N rate. ‘Salam’ showed a positive response to N fertilization in terms of root 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 each species showed similar behavior. In Paspalum, pigment content was not affected by salinity level, though chlorophyll a slightly decreased at the highest salinity level.