Camelina germination under osmotic stress − Trend lines, time-courses and critical points

Camelina [Camelina sativa (L.) Crantz] has increased cold, heat, and drought tolerance and decreased susceptibility to diseases and pests than oilseed rape (Brassica napus L.). Because water deficit at sowing leads to unsatisfactory stand establishment due to irregular seed germination and emergence, the aim of this study was to understand the response of camelina germination under osmotic stress and identify critical soil moisture levels for successful establishment. Two spring cultivars, NS Slatka and NS Zlatka, developed at the Institute of Field and Vegetable Crops Novi Sad, Serbia, were compared under 9 levels of osmotic stress, ranging from 0 MPa to −1.6 MPa. Polyethylene glycol was used to obtain the osmotic potential of the solutions. Results showed that the tested cultivars did not decrease germination under mild and medium osmotic stress levels (down to −0.8 MPa). However, germination significantly decreased in both cultivars under higher levels of osmotic stress, and NS Zlatka was more sensitive. Germination speed significantly increased at −0.4 MPa. The estimated osmotic potentials to stop germination were −1.45 MPa for NS Slatka and - 1.46 MPa for NS Zlatka. Time to 50% germination also showed a significant bi-linear trend in response to osmotic potential, but in the opposite direction than the one observed in germination. Inflection points were recorded at −0.77 MPa for NS Slatka and −0.78 MPa for NS Zlatka, thereafter time to 50% of germination rapidly increased. This study confirmed that camelina can withstand increased levels of drought stress at germination, so it could be considered a more suitable option than oilseed rape on marginal land, or environments with irregular precipitation.