Salinity-induced responses and resistance in Trifolium repens L.

Abstract

White clover (Trifolium repens L.) is a commonly cultivated legume with good ground cover potential often used with companion grass species in urban grassed areas. The effect of increased soil salinity on plant growth is an urgent problem in cities where NaCl is used as a de-icing material. The aim of this research was to examine the effect of different salinity levels and K supply-induced responses and tolerance in the T. repens L. variety ‘Daile’, a variety which is used in urban greenery. To analyze the impact of increased soil salinity and the antagonistic effect of K, the effect of gradually increasing NaCl (0, 20, 40, 60, 80, 100mM) and K (+0, +100, +200, +300mg/L) levels on T. repens plants was investigated in a pot experiment. Concentrations of 12 nutrients, Na and Cl were determined in the plant shoots and roots, as well as plant weight, Pv/Fm, P index (photosynthetic performance) and proline content. The results revealed that increased substrate salinity led to accumulation of both Na and Cl in tissues of T. repens and significantly reduced Mg. Na and Cl concentration in the plant shoots increased in accumulative manner, but in the roots, the concentration of both elements increased in the treatments with applied NaCl concentrations up to 60mM. In the roots, a significant decrease in N, K, Mg, S, Mo and an increase in Na, Cl, Ca, Fe, Mn, Cu, Zn content was detected with increasing substrate salinity. Elevated soil salinity had a minor impact on the photosynthetic performance of T. repens. A significant decline in the fresh and dry biomass of the plant shoots was measured in all salinity treatments. In conditions of increasing soil salinity and K content, T. repens possessed several mechanisms of adaptive value, as well as changes in mineral nutrition. According to the obtained results, cultivation of T. repens variety ‘Daile’ in urban areas with slight or moderate salinity is possible.