Nitrogen fertilization effects on lesquerella production

Progress has been made towards the commercialization of Lesquerella fendler i (Gray) Wats. as a fall-planted oilseed crop for the southwestern United S tates. Research to develop suitable cultural practices for commercial produ ction of lesquerella has been underway since the late 1980s; however, infor mation is limited on the plant's nitrogen (N) requirement. Field experiment s were conducted during two growing seasons to determine the optimum amount and timing of N applications for lesquerella production. Yield results ind icate that lesquerella grown on desert soils is strongly influenced by N fe rtilization. Nitrogen rates as high as 180 kg N ha(-1) increased seed yield . Seed oil content decreased as the N rate was increased. The increase in s eed yield at the higher N rates generally offsets the decrease in oil conte nt, but oil yields appeared to be near maximum at 180 kg N ha(-1). Split-ap plications of N in the Spring increased seed and oil yields in one of two s easons. Nitrogen had no influence on 1000-seed weight or lesquerolic acid c ontent of the oil. No Spring leaf blade total N level was identified as bei ng related to maximum seed yield. A suggested N management program for lesq uerella production is to apply a small portion of N at planting time and th e major portion of N in several applications during the period from onset o f bloom through full bloom (February-April). (C) 1999 Elsevier Science B.V. All rights reserved.