Quantifying the effect of osmotic and salt stress on germination of Egyptian spinach (Corchorus olitorius L.) and Asian spiderflower (Cleome viscosa L.)

Egyptian spinach (Corchorus olitorius L.) and Asian spiderflower (Cleome viscosa L.) are two of most important weeds in Khouzestan province corn fields. This experiment was conducted to quantifying the effect of osmotic and salt stress on germination of these weeds. In order to describing effect of reduced water potential on germination of these weeds solutions were prepared with osmotic potentials of 0, -0.2, -0.4, -0.6, -0.8 and -1.0 MPa by dissolving appropriate amounts of polyethylene glycol 6000 in distilled water. Also, Water solutions with salinity of 0, 50, 100, 150, 200, 250, 300, 400 and 500 mM were prepared by dissolving NaCl in distilled water. The hydrotime constant (θH), the base or threshold water potential (Ψb(0)) and the median base water potential (Ψb(50)) of these weeds were as follows: C. viscose (14.30 MPa h, -1.32 and 0.89 MPa) and C. olitorius (11.85, -1.13 and -0.88 MPa), respectively. Threshold response of 50% maximum germination reduction to salinity of C. viscose and C. olitorius were 246.80 mM and 217.00 mM, respectively. Totally, seed germination of C. viscose and C. olitorius were partially tolerate and tolerant to osmotic stress and salinity, respectively.