ALLEVIATION OF OXIDATIVE EFFECTS OF SALT STRESS IN WHITE LUPINE (LUPINUS TERMIS L.) PLANTS BY FOLIAR TREATMENT WITH L-ARGININE

Abstract

Salinization is one of the most important stress factors which reduce the growth and crop productivity of plants in various climatic regions. In this greenhouse study, the effects of 2.5 mM arginine as foliar spray on growth and some chemical constituents of lupine plants irrigated with three different levels of NaCl (75, 150 and 300 mM NaCl) were evaluated. The results indicated that the plants exposed to salinity stress exhibited a significant decline in growth parameters (shoot length, root length, number of leaves, fresh and dry weights of shoots and roots) and photosynthetic pigment content. On the other hand, salt stress caused significant increase in total free amino acids and total protein contents in comparison with control plants. In addition, proline content and lipid peroxidation increased with increasing concentrations of NaCl. Treatment with 2.5 mM arginine as foliar spray mitigated salt stress by inducing enzyme activities responsible for antioxidation, e.g., superoxide dismutase, ascorbate peroxidase, glutathione reductase, detoxification as well as improving all the above recorded parameters. Furthermore, treating the plants with 2.5 mM arginine alone or in combination with salt stress leads to differential expression of the genetic information in lupine plants, resulting in changes in gene products, including protein and isozymes profiles. These changes induced the synthesis of certain proteins and simultaneously decreased the expression of other protein sets. These findings confirm the effectiveness of spraying lupine plants with arginine on alleviating salinity stress in lupine plants.