PreACT Practice Test 9

Salt and radish seed germination

Salt in soil water can slow or prevent seed germination (the sprouting of a seed). Researchers studied how sodium chloride (NaCl) affects radish seeds. In every study, 50 seeds were placed on filter paper in a covered dish and wetted with 10 mL of a solution. After 5 days, the researchers counted the seeds that had sprouted and calculated the percent germinated.

Study 1. Dishes were wetted with solutions of 0, 50, 100, 150 or 200 millimolar (mM) NaCl and kept at 22°C (Table 1).

Study 2. Dishes were wetted with 0 mM or 100 mM NaCl and kept at 12°C, 17°C, 22°C or 27°C (Table 2).

Study 3. Some seeds were primed: soaked in distilled water for 12 hours and blotted dry before being placed in a dish. Primed and unprimed seeds were wetted with 100 mM NaCl and kept at 22°C (Table 3). Seeds in Studies 1 and 2 were unprimed.