Planting date and nitrogen fertilization effects on lesquerella production

Lesquerella (Lesquerella fendleri (Gray) Wats.) produces seed containing hydroxy fatty acids similar to castor oil and has good commercial potential. An important step in the commercialization of this plant for the southwestern desert regions of the United States is the development of an efficient agronomic production system. Field experiments were conducted during the 1991-1992, 1992-1993, and 1993-1994 growing seasons at the University of Arizona, Maricopa Agricultural Center, Maricopa, Arizona to determine the effect of planting date and nitrogen fertility on lesquerella seed yield. Results indicate that fall plantings are necessary to obtain high seed production. September plantings generally produced higher yields than the October or November plantings. February plantings produced low yields and appear to be too late Cor a growing season that ends in June in central Arizona. In all years, lesquerella responded to nitrogen (N) fertilizer. The addition of 60 to 120 kg N/ha increased biomass and seed yields. Nitrogen fertilizer did not affect 1000-seed weight, but decreased seed oil content in the 1993-1994 planting. There is evidence that increasing the N application rate decreases seed oil content in lesquerella.