Salinity and Nitrogen Rate Effects on the Growth and Yield of Chile Pepper Plants

Salinity and low soil N availability are important growth limiting factors for most plants. Our objective was to determine the influence of different N fertilization rates and soil salinity levels on the growth and yield of chile pepper plants ( Capsicum annuum L.) grown in a greenhouse in sandy loam soil for 2 yr. The targeted soil salinity levels were 1.3, 3.5, and 5.5 dS m −1 in 1999, and 1.3, 3.0, 4.5, and 6.0 dS m −1 in 2000 as electrical conductivity of the saturated paste extract (EC e ). Total N application rates were 80, 140, and 200 kg ha −1 in 1999, and 30, 90, and 150 kg ha −1 in 2000. Nitrogen rates of 140 kg ha −1 or more increased soil salinities, in some cases by as much as 4 dS m −1 Soil salinity decreased plant relative growth rate (RGR) up to first mature pod stage. After this growth stage however, salinity increased the RGR. Low and medium N rates produced the maximum RGR up to the first mature pod stage. After this growth stage, the maximum RGR was achieved with the medium and the high N rates tested in 1999 and 2000, respectively. Increasing N rates and salinity levels interacted to reduce chile pod yield in 1999, and acted independently in 2000. This study indicates that over‐fertilization during early plant development may contribute to salinity and decreased pod yield. While salt‐stressed chile performs well when adequately fertilized, N should be applied in amounts that increase with plant need over the growing season.