Study the relationship between seed size and aging on cardinal temperatures of Canola

To study the relationship between seed size and aging on cardinal temperatures of canola cv. Hyola 50, seed germination an experiment was conducted based on a randomized complete design with three replications. Seeds were classified in to four groups based on their diameter (1.4, 1.8, 2 and 2.2 mm) and considered as the first experimental factor. The Second factor was various durations of accelerated aging treatment (0, 24, 48, 72, 96 and 120 hours (40oC, RH=100%) and the third factor was nine constant temperatures in which seeds were germinated (0, 5, 10, 15, 20, 25, 30, 35 and 40 ˚C). Cardinal temperatures were quantified for germination fraction of 50% using four nonlinear model: beta, beta modify, dent-like and segmented. The result indicted beta model better described responses germination rate to temperature compared with others models and accelerated aging and sizes did not affect the change model base temperature was about 1.15 OC in sizes 1.4 mm and increase in size to 2.2 mm deceased to 0.11 OC. The optimal temperature range was about 21.37 to 21.58 OC and the maximum temperature was 40.2 to 40.8 OC. it was also found that different seed sizes did not have a significant difference in terms of thermal time and deterioration increased the basal germination temperature and thermal time coefficient and reduced the optimal and maximum temperature, that it can show necessity delay in planting date in cold areas or early planting in tropical areas in these types of seeds.