NaCl stress, tissue specific Na+ and K+ up-take and their effect on growth and physiology of Helianthus annuus L. and Solanum lycopersicum L.

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Salinity is one of the major abiotic stresses that can threat plant growth and yield. Helianthus annuus L. and Solanum lycopersicum L. are economically important crops and widely cultivated, but the uptake of Na+ and K+ during the NaCl stress in their above and below ground parts is not well-understood. The main objective of this study was to understand the response of leaf structure and function to different concentrations of NaCl and to understand the Na+ and K+ uptake in H. annuus and S. lycopersicum. Four different concentrations of NaCl (H. annuus; 50 mM, 100 mM, 150 mM, 200 mM, and S. lycopersicum; 25 mM, 50 mM, 75 mM, 100 mM) were applied. Plant Biomass and the leaf structure and function (leaf area, midrib length, secondary vein length, petiole diameter, photosynthesis, stomatal conductance, transpiration, and intrinsic water use efficiency) were studied. We found that the salinity concentration of more than 150 mM in H. annuus and 75 mM in S. lycopersicum significantly reduced the plant height and leaf performance. At the same time, the yield (seed and fruit weight) decreased at 100 mM and 50 mM of NaCl concentration of H. annuus and S. lycopersicum, respectively. Maximum Na+ and K+ were accumulated in roots and stem in H. annuus and roots and fruits in S., lycopersicu. At the same time, the minimum Na+ and K+ were detected in seeds of H. annuus and fruit and root of S. lycopersicum. The K+: Na+ showed variation in both crops. We conclude that the vegetative parts of Helianthus annuus can tolerate up to 150 mM and S. lycopersicum up to 75 mM of NaCl concentration. The concentration of Melatonin increases as the stress level increases as it acts to remove the stress. These findings can be helpful to cultivate the Helianthus annuus and S. lycopersicum in saline areas and can also be useful to cultivate other crops when the successive cultivation of both crops is practiced and Na+ is absorbed by the crop from the soil.