Effect of seed aging on germination and seedling growth indices in three cultivars of Brassica napus L.

Accelerated aging test is the most important tests used to evaluate the physiological potential of seeds of various species and provide the information of their compatibility degree. In this investigation the impact of seed deterioration (accelerated aging test) on germination and seedling growth indices was conducted in three cultivars of canola; SLM، Elite and Zarfam. The accelerated aging test was carried out at three different temperatures: 30، 40 and 50 °C with four duration periods of 24، 72، 120 and 144 hr and a 100% relative humidity in factorial experiment that laid out in randomized complete block design with three replications. The results showed that accelerated seed aging and cultivar، temperature and duration period interactions have significant effect on germination percentage (GP)، Index (GI) and rate (GR)، D50 and seed vigor (SV). All germination indices (GP، GI، GR، D50 and SV) and seedling growth included length and weight of root and shoot and allometric coefficient decreased in three cultivars with increasing in seed aging temperature and duration period. Results indicated that Zarfam cultivar has maximum rate of germination and seedling growth indices rather than two other cultivars. This good quality will continued in accelerated seed aging. So that Zarfam، Elayt and SLM germination percentage under 40 °C and 144 h accelerated seed aging declined from 80 percent to 64 and 29 percent respectively. Zarfam and SLM were having highest and lowest seed quality and resistance to storage conditions، respectively under long period of storage in hot and humid weather.