Abstract:

In many areas where tall fescue is cultivated， soils are salinized or may become salinized because of frequent irrigation. The application of silicon （Si） can improve the salt tolerance of plants by reducing the absorption of sodium and increasing the absorption of nitrogen， phosphorus， and potassium， although the extent to which Si improves salt tolerance varies among plant species and varieties. In this study， pot experiments were conducted to investigate the effects of Si application on the biomass of two tall fescue （Festuca arundinacea） cultivars （K31 and XD） under salt stress and on the N， P， K⁺， and Na⁺ concentrations in their shoots and roots. The two cultivars differed in their salt tolerance； K31 was salt-sensitive while XD was highly salt-resistant. The two cultivars were grown in a mixture of vermiculite and perlite with a range of salinities. As the salinity increased， the shoot and root biomass decreased， the N， P， and K⁺ concentrations in the shoots and roots of the two cultivars decreased， and the Na⁺ concentrations increased. These negative effects of salinity were ameliorated by Si， and to a greater extent in the salt-tolerant cultivar than in the salt-sensitive cultivar. The application of Si increased shoot and root biomass， the root∶shoot， N， P， K⁺ concentrations， and the K⁺∶Na⁺， and decreased Na⁺ concentrations in the shoots and roots of both tall fescue cultivars in medium- and low-salinity treatments. However， Si application did not affect these parameters in the high-salinity treatments because the salinity level exceeded the degree of salt tolerance and Si was not able to regulate plant responses. The application of Si had a similar effect on shoot and root biomass and on Na⁺ and P concentrations in the two cultivars， but different effects on K⁺ and N concentrations. The beneficial effects of Si on K⁺ and N concentrations in shoots of salt-stressed plants were stronger in the salt-tolerant cultivar XD than in the salt-sensitive cultivar K31. These results indicate that Si can promote the growth of tall fescue under low and medium salinities， and is especially effective for salt-tolerant tall fescue cultivars.

Key words: tall fescue, Si application, biomass, N， P and K uptake, salinity