Salinity and Soil Type Effects on Emergence and Growth of Pepper Seedlings

Abstract

High soil salinity often results in poor stand establishment, reduced plant growth, and reduced yield of many horticultural crops such as peppers (Capsicum annuum). We investigated the effects of soil salinity and soil type on seedling emergence and growth of four commercial peppers (‘NuMex Joe E. Parker’, ‘NuMex Nematador’, ‘NuMex Primavera’, and ‘Jupiter’) in greenhouse experiments. Seeds were sown in either a loamy sand or a silt loam soil in pots and irrigated with saline solutions at electrical conductivity of 0.9 (tap water), 3.0, or 6.0 dS·m−1 (Expt. 1) or at 0.0 [reverse osmosis (RO) water], 0.9, or 1.5 dS·m−1 (Expt. 2). No seedling emergence was observed in treatments irrigated with 3.0 or 6.0 dS·m−1 solutions. The salinity at the top soil layer increased linearly with time when subirrigated with tap and saline solutions in both soil types, whereas no substantial increase in soil salinity was found when subirrigated with RO water or overhead irrigation with tap water. Salt accumulation at the top soil layer was greater in loamy sand than in silt loam. Seedling emergence percent subirrigated with RO water ranged from 70% to 80% in loamy sand and 45% to 70% in silt loam, depending on pepper cultivars. When subirrigated with tap water and saline solutions, the emergence percent ranged from 0% to 60%, depending on pepper and soil types. In Expt. 3, seedlings were germinated in commercial potting mix and grown in 1.8-L pots containing commercial potting mix. Saline solution treatments of 1.4 (control, nutrient solution), 2.1, 2.9, 3.5, or 4.2 dS·m−1 were initiated when seedlings had 11 to 13 leaves. Five weeks after initiating saline water irrigation, the reduction in shoot dry weight was greater in ‘Jupiter’ and ‘NuMex Primavera’ as compared with ‘NuMex Joe E. Parker’ and ‘NuMex Nematador’, but the differences were small.