SALINITY EFFECTS ON GROWTH, LEAF-ION CONTENT AND SEED PRODUCTION OF LESQUERELLA-FENDLERI (GRAY) WATS,S

Little information is available on the response of lesquerella grown u nder saline conditions. This field study was initiated to determine th e responses of lesquerella to salinity relative to growth, seed yield and oil content. Six salinity treatments were imposed on a Holtville s ilty clay (clayey over loamy, montmorillonitic (calcareous), hyperther mic Typic Torrifluvent). The plots were irrigated with Colorado River water artificially salinized with NaCl and CaCl2 (1:1 by weight). Elec trical 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-io n content, seed yield, oil content and fatty acid composition of the s eed were measured. Seed yield decreased from 2100 kg ha(-1) under nons aline control conditions to 650 kg ha(-1) at the highest salinity leve l. Analysis of the combined two-year data showed a 19% reduction in se ed 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 a nd 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, b ut significantly, with increases in soil salinity. The fatty acid comp osition showed a minor, but again significant, increase in linolenic a cid (C18:3) content as salinity increased. With this exception, oil co mposition did not change with salinity level, including the content of lesquerolic acid in the oil. (C) 1997 Elsevier Science B.V.