Effect of Salt and Drought Stresses on Germination Components in Canola (Brassica napus L.)

ABSTRACT: Salinity and drought stress are the most environmental factors that affect different development stages of crops, especially germination stage. The objective of the present investigation was to study the of germination components (Gmax, GS, GR, T10, T50, T90 and GU) of canola ‘Okapi’ under different levels of salinity and drought stress. For this purpose, seeds were germinated at iso-osmotic concentrations of NaCl and PEG-6000 (0, -0.1, -0.2, -0.3, -0.4, -0.6 and -0.8 MPa). The results showed maximum germination (Gmax) was obtained 72% in 0 MPa and decreased to 54.2 and 26.1% in -0.8 MPa for NaCl and PEG, respectively. In PEG, germination slope (GS) was the lower in -0.6 and -0.8 MPa than other water potentials, while in NaCl it was not significant among water potentials. The value of T50 (time to 50% Gmax) was estimated 50.4 h in 0 MPa and increased to 62.5 and 123.7 h in -0.8 MPa for NaCl and PEG, respectively. In NaCl, WPc (water potential which germination components are constant above it) for germination rate (GR) and T10 (time to 10% Gmax) were estimated -0.5 and -0.39 MPa. GR had declining slope in lower than WPc (0.012 h-1 MPa) and but it was increasing for T10 (27.1 h MPa). T90 (time to 90% Gmax) and germination uniformity (GU) linearly increased with slope 94.6 and 97.4 h. In PEG, WPc for GR, T10, T90 and GU were estimated -0.32, -0.27, -0.30 and -0.30 MPa, respectively. GR decreased with slope 0.026 h-1 MPa, while T10, T90 and GU had a increasing slope (61.1, 185.3 and 108.7 h, respectively). In generally, it concluded that NaCl has a less inhibitory effect on seed germination than an iso-osmotic concentration of PEG.