اثرات تاريخ هاي مختلف كاشت بر نبيه بذر سويا

The influence of planting dates on soybean seed vigor

So far no study about the relation between the planting date and seed vigor of soybean has been conducted in Iran. Three soybean cultivars, Williams ,T1 x SRF and Per*T1 were sown in different dates, and their seeds were harvested at physiological maturity. The percentage and rate of emergence, the length and dry weight of root and shoot and the total seedling dry weight were measured under laboratory and greenhouse conditions. The experiments were done using completely randomized design with three replications in factorial arrangement. The results showed that for all cultivars, the emergence percentage increased with delay in planting date, so that the emergence percent increased from 18.7%(in the planting date of 9 April) to 64.2% (in the planting date of 4 July). Also, the results showed that the rate of emergence was less in comparison with the percentage of emergence. The length and the dry weight of the root and shoot produced by earlier planting date were less than later planting date. In other words, the seeds that were produced in later planting dates (middle June) faced with favorable condition in comparison with the earlier planting date (April) and seed vigor was higher in delayed planting dates.