Seedling emergence, growth, and mineral nutrition of ornamental chile peppers irrigated with saline water
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Ornamental chile peppers are popular bedding plants. As high-quality water supply becomes limited in many parts of the world, alternative waters such as municipal reclaimed water is encouraged to be used for landscape irrigation. The purpose of this study was to assess the relative salt tolerance of 10 cultivars of ornamental chile peppers by irrigating the mature plants with saline solutions and germinating seeds in saline substrate in a greenhouse. In the mature plant salt tolerance experiment, plants were irrigated with nutrient solution (no addition of salts, control) or saline solution at electrical conductance (EC) of 4.1 dSm-1 or 8.1 dSm-1 for 8 weeks. Plants in the EC of 4.1 dSm-1 treatment did not have any foliar salt damage regardless of cultivar. At EC of 8.1 dSm-1, 'NuMex Memorial Day' had the most severe foliar salt damage, whereas 'NuMex April Fool's Day', 'NuMex Cinco de Mayo', 'NuMex Thanksgiving', and 'NuMex Twilight' had little or no foliar damage. Shoot dry weight (DW) reduction at EC of 8.1 dSm-1 compared with control was smallest in 'NuMex Thanksgiving' (15%), whereas 'NuMex Memorial Day' had the greatest reduction of 74% followed by 'NuMex Christmas' of 61%. The highest shoot DW reduction in 'NuMex Memorial Day' coincided with lowest visual score, indicating that this cultivar was the least tolerant to salinity. The leaf Na+ and Cl- concentrations increased dramatically with increasing EC of the irrigation water in all cultivars. The highest Na+ concentration of 10.9 mggL1 DW at EC of 8.1 dSm-1 was observed in 'NuMex Christmas'. The highest Cl- concentration at EC of 8.1 dSm-1 was found in 'NuMex Memorial Day' with 64.8 mggL1 DW, which was four times higher than the control.In the seedling emergence experiment, seeds ofthe 10 cultivars were germinated in substrate either moistened with reverse osmosis water (EC 0) or saline solution at EC of 17.1 dSm-1. 'NuMex Christmas' and 'NuMex Memorial Day' had the lowest relative seedling emergence index, indicating that these two cultivars were the least tolerant to salinity during the seedling emergence stage. 'NuMex Thanksgiving' and 'NuMex Cinco de Mayo' had the highest relative seedling emergence index. Combining the results from both experiments, weconcluded that 'NuMex Cinco de Mayo' and 'NuMex Thanksgiving' were the most tolerant cultivars, whereas 'NuMex Christmas' and 'NuMex Memorial Day' were the least tolerant ones.
