Salinity effects on growth, leaf-ion content and seed production of Lesquerella fendleri (Gray) S. Wats

Abstract

Little information is available on the response of lesquerella grown under saline conditions. This field study was initiated to determine the responses of lesquerella to salinity relative to growth, seed yield and oil content. Six salinity treatments were imposed on a Holtville silty clay (clayey over loamy, montmorillonitic (calcareous), hyperthermic Typic Torrifluvent). The plots were irrigated with Colorado River water artificially salinized with NaCl and CaCl 2 (1:1 by weight). Electrical conductivities of the irrigation treatments in both years were 1.4, 2.2, 4.0, 6.0, 8.0, and 10.0 dS m −1. Vegetative growth, leaf-ion content, seed yield, oil content and fatty acid composition of the seed were measured. Seed yield decreased from 2100 kg ha −1 under nonsaline control conditions to 650 kg ha −1 at the highest salinity level. Analysis of the combined two-year data showed a 19% reduction in seed yield for each unit increase in soil salinity above a threshold of 6.1 dS m −1. Based on these results, lesquerella can be classified as a salt tolerant crop. In response to increases in salinity, leaf Ca and Cl increased, whereas Mg decreased. Sodium was effectively excluded from leaf tissue at all levels of salinity. Concentrations of Na were generally an order of magnitude lower in lesquerella leaves than has been reported in leaves of other cruciferous crops grown under saline field conditions. Total oil content of the seeds increased slightly, but significantly, with increases in soil salinity. The fatty acid composition showed a minor, but again significant, increase in linolenic acid (C18:3) content as salinity increased. With this exception, oil composition did not change with salinity level, including the content of lesquerolic acid in the oil.