Salt-Induced Changes in Growth and Damage Avoidance Mechanisms of Hydroponically Grown Chinese Kale (Brassica alboglabra L.)
Accretion of nonessential ions such as sodium and chloride due to the selective ion-uptake process into the root and/or the use of poor-quality irrigation water may adversely affect the production potential of crops such as Chinese kale in closed-loop hydroponic systems. This research identifies the effects of salt on the plant’s growth and the damage avoidance mechanisms in foliage of hydroponically grown Chinese kale. Twenty-one-day-old plants (at the 4-leaf stage) were exposed to salinity (0, 25, 50, 75, and 100 mM NaCl) for 16 days. Results indicated that growth parameters, leaf water status, photosynthetic pigments, and photosystem II efficiency declined as salinity increased in the rhizosphere, whereas proline biosynthesis was stimulated progressively. Salinity induced higher H2O2 endogenesis and lipid peroxidation while triggering antioxidant enzymes activity in the leaf tissues. Activity of ascorbate peroxidase and peroxidase gradually increased with salinity, although peroxidase activity was decreased at high salinity (>75 mM NaCl). Catalase, a crucial component of the free radical neutralization process, was also observed at high salinity (>75 mM NaCl). Chinese kale plants were tolerant to salinity at 25 mM and employed a complex mechanism composed of an excess energy dissipation system along with the enzymatic antioxidant system, thus making it relatively tolerant to salinity beyond 75 mM NaCl.
KeywordsSalinity Chlorophyll fluorescence Oxidative stress Lipid peroxidation Antioxidant enzymes
The authors gratefully acknowledge the Universiti Putra Malaysia for financial support.
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