Response of Purslane (Portulaca oleracea L.) to Excess Boron and Salinity: Physiological Approach

Resumo

In this study, individual and combined effects of boron and sodium chloride salinity on growth, photosynthetic pigments (chlorophyll and carotenoids content), enzymatic activities (catalase and ascorbate peroxidase), hydrogen peroxide content, malondialdehyde content, proline accumulation, and some ion contents, such as B^–, Na⁺, Cl^–, K⁺, Ca²⁺, Mg²⁺ of purslane (Portulaca oleracea L.) were investigated. Five B levels (0, 4, 8, 16, 24, 40 mg/kg) and 100 mM NaCl were applied to the soil and mixed before sowing. Results showed that purslane growth was reduced significantly by higher B levels and salinity due to ion toxicity and osmotic stress. Also, content of photosynthetic pigments increased with both higher B levels and salinity, but they were decreased with combined effects of them. Tissue B^–, Na⁺, Cl^–, K⁺ and Ca²⁺ levels in shoot increased with applied NaCl, but B levels applied together with NaCl caused a decrease in B^– content due to antagonistic effects between B^– and Cl^– ions. The MDA content, proline accumulation, and H₂O₂ content increased with higher B levels, but salinity caused a decrease in MDA content. The catalase and ascorbate peroxidase activities increased with B and salinity combination, but did not change with salinity. Increasing B reduced the catalase activity. It is suggested that purslane has the potential to manage the amount of soluble boron and also it has a promising potential that can be grown in B-rich and saline soils.