GROWTH, SEED YIELD, AND OIL CONTENT OF CANOLA GROWN UNDER SALINE CONDITIONS

Due to health concerns regarding saturated fat in the human diet, cano la (Brassica spp.) is becoming an increasingly important source of edi ble vegetable oil because of its low saturated fat content. This incre ased demand, and the need for crop diversification, will undoubtedly p romote increased acreage of canola in the western USA, where some soil s are or have the potential to become saline. Salt tolerance in two ca nola species (B. napus L. cv. Westar and B. campestris L. cv. Tobin) w as determined in a 2-yr field plot study. Six salinity treatments were imposed on a Holtville silty clay (clayey over loamy, montmorilloniti c [calcareous], hyperthermic Typic Torrifluvent) by irrigating with wa ters salinized with NaCl and CaCl2 (1:1 w/w). Electrical conductivitie s of the irrigation waters ranged from 1.2 to 9.7 dS m-1 the first yea r, and 1.2 to 11.5 dS m-1 the second year. Seed yield, vegetative grow th, oil content, and protein content in the oil-free seed meal were me asured. Relative seed yields of Westar and Tobin were unaffected by so il salinity up to 11.0 and 9.7 dS m-1 (electrical conductivity of the saturated soil extract: EC(e)), respectively. Each unit increase in sa linity above the thresholds reduced the seed yield of Westar by 13.0% and Tobin by 14.3%. These results place both canola species in the sal t-tolerant category. Increased salinity did not significantly affect t he oil or protein content of the oil-free seed meal. Vegetative growth of both species was unaffected by soil salinity up to 10.0 dS m-1 and the growth decline above this threshold was 11.2% per unit increase i n salinity.