Calcium supplementation ameliorates salinity stress in Lactuca sativa plants

Abstract: Salinity represents an increasing threat to agricultural production in every region of the world. The objective of this investigation was to determine ameliorative effects of calcium chloride (CaCl₂) on salt stressed lettuce (Lactuca sativa) in terms of growth, pigments and biochemical contents. The treatments were divided into 4 sections: control, 80mM NaCl, 80mM NaCl +5mM CaCl₂ and 5mM CaCl₂ alone. NaCl and CaCl₂ stress decreased lettuce plant root and stem length, number of leaves and fresh weight versus the control. NaCl combined with CaCl₂ increased these parameters versus treatments with NaCl or CaCl₂ alone. Salt stress reduced the shoot and root fresh weight. The roots showed slightly increased growth under salinity, but after the treatment with CaCl₂ the plants were normal. The pigment chlorophyll showed a diminishing trend in NaCl stressed plants, but it increased with CaCl₂ application. The chlorophyll content increased in all plants with age. There was a slight decrease in carotenoid and anthocyanin contents with NaCl treated plants. CaCl₂ also showed decrease in carotenoid and anthocyanin contents, but it was still higher than that of NaCl treated plants. Proline and phenol contents increased in lettuce plants under treatment with NaCl and CaCl₂ when compared to the control. From these results, it can be concluded that the addition of CaCl₂ to NaCl-stressed lettuce plants have a significant role in partial alleviation of salinity stress. Our results indicated that the cultivation of vegetable plants like lettuce in saline areas would be possible with supplemental calcium application.