Effect of soil salinity on growth, water status and nutrient accumulation in seedlings of Cassia montana (Fabaceae)

Greenhouse experiments were conducted to assess the effects of soil salinity on emergence, growth, water status, proline content and mineral accumulation of seedlings of Cassia montana Heyne ex Roth (Fabaceae). NaCl was added to the soil and salinity was maintained at 0.3, 3.9, 6.0, 7.9, 10.0, 12.1 and 13.9 dS m−1. A negative relationship between seedling emergence and salt concentration was obtained. Nevertheless, this tree species is salt-tolerant at seed germination stage. Stem and root elongation, leaf expansion and dry matter accumulation in leaves, stems, tap roots and lateral root tissues were stimulated by salt. Results suggested that C. montana is a halophytic plant. Increase in growth of plants of this species can be attributed to osmotic adjustment and increased leaf area. The K and Na profiles of this plant suggested its two distinct traits: (i) high Na+ influx and/or low Na+ efflux on root plasma membrane and (ii) high K+/Na+ discrimination. This plant is also efficient in Na transport to stems and leaves. Changes in tissues and whole-plant accumulation patterns of nutrients, as well as possible mechanisms for avoidance of Na toxicity in this tree species in response to salinity, are discussed.