Water shortages and poor water quality are critical issues in many regions of the world. With a rapidly increasing population and diminishing water supplies, the competition for fresh water among agriculture, industry, urban, and recreational users has become intense. Use of alternative water sources such as municipal reclaimed water and other poor-quality, non-potable saline waters for irrigating agricultural crops such as chile peppers may be inevitable in the water scarce southwestern states of the United States. Soil salinity is already a growing problem in arid and semiarid southwestern states as a result of low rainfall and high evaporation. Irrigating crops with low-quality water can increase soil salinity (Pasternak and Malach, 1994; Villa-Castorena et al., 2003) leading to low productivity in many regions of the world (Rozema and Flowers, 2008). Plant physiological and growth responses to salinity differ between species and among genotypes within a species (Maas and Hoffman, 1977; Pasternak and Malach, 1994). Among horticultural crops, peppers are considered moderately sensitive to salinity (Pasternak and Malach, 1994), although some species/cultivars may be more tolerant than others. In New Mexico and western Texas, with a typical semiarid climate, high soil salinity often leads to poor stand establishment of high-value crops such as chile peppers and onions (Allium cepa) (Corgan et al., 2000; Phillips, 2003).
One of the most effective ways to overcome salinity problems is the introduction of salt-tolerant crops. However, limited information exists for salt tolerance of various horticultural crops, including chile peppers. Earlier studies classified pepper as moderately sensitive to salt stress and yield began to decline once the soil electrical conductivity (EC) level exceeds 1.5 dS·m−1 (Maas and Hoffman, 1977; Pasternak and Malach, 1994). However, limited recent studies have indicated that some genotypes are more tolerant to salinity than others. Substantial variations in the response of 102 pepper genotypes to salinity were observed in a greenhouse experiment based on the severity of leaf symptoms caused by NaCl stress at 100 mm (9.1 dS·m−1) (Aktas et al., 2006). Similarly, Chartzoulakis and Klapaki (2000) reported differences in two bell pepper hybrids, ‘Lamuyo’ and ‘Sonar’, in response to salinity based on growth and yield. Such evaluations may facilitate improvement of salt tolerance of pepper genotypes in breeding programs or it may prove feasible to irrigate with saline water for more tolerant genotypes. In addition, anecdotal observation indicated that it is more difficult for chile pepper seeds to germinate and establish in mineral soils compared with commercial potting mix. Elevated soil salinity and/or inadequate water supply can further reduce seedling establishment. The objective of this study was to evaluate the relative salt tolerance of 20 genotypes (Anaheim, Ancho, Cayenne, Paprika, Jalapeño, Habanero, and Serrano) of chile peppers in two separate experiments using potting mix and mineral soil based on seedling growth, survival, and visual quality.
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