[Response of alfalfa seed to stress storage conditions]

The seed germination rate, seed mortality, seedling length, and infection rate of alfalfa (Medicago sativa L. cv. 'Longdong') were measured at constant temperature 20 degrees C every 60 days during one year storage period after inoculated or no inoculated by Fusarium avenaceum under room temperature (RT), 35 degrees C, and 35 degrees C and +10% seed moisture content (SMC) conditions. Field emergence rates of seeds under above treatments were also observed, and seed-borne fungi were detected under the conditions mentioned above and controlled deterioration (CD) as well. The results showed that the percentage of isolated alfalfa seed-borne fungi was increased from 10% under room temperature and 35 degrees C to 29% under 35 degrees C + 10% SMC. Disease resistance was declined, and seed mortality and seedling infection rate under 35 degrees C + 10% SMC were significantly higher than those under room temperature and 35 degrees C respectively (P < 0.05). The seed germination rate and field emergence rate were also decreased significantly (P < 0.05). Seedling shoot and root length under 35 degrees C + 10% SMC were significantly less than those under RT and 35 degrees C respectively (P < 0.05). The percentages of both seed-borne fungi isolated and field emergence were decreased, and that of seedling infection was increased with storage period extending from 60 to 360 days. Compared to no inoculated control, the percentage of seed germination, seedling shoot and root length were decreased, and seed mortality and seedling infection rate were increased after inoculated by F. avenaceum.