Some aspects of seed germination in two mustard species influenced by temperature, planting depth and flooding period

All phases of this research were conducted in Research Laboratory, Faculty of Agriculture, Tarbiat Modares University in 2017. Before starting the experiments, seeds of wild mustard (Sinapis arvensis) and white mustard (S. alba) were collected from East Azarbaijan and Khuzestan provinces at maturity (late spring and early summer) during the 2015-2016 growing season and were stored for seven months. This study included three experiments. Each experiment was arranged in a completely randomized design with four replications, and the treatments were factorial. In all experiments, one of the factors was the mustard species. In the first experiment, the second factor consisted of eight temperatures ranging from 5 to 40 °C. In the second experiment, the second factor was 13 sowing depths of 0.5 to 6 cm. In the third experiment, the second factor included six flooding periods from 0 to 35 days. The results of the experiments showed that in most temperatures, the depths and flooding periods, germination of wild mustard were greater than white mustard, which is probably due to the larger size of the seed of this species. The onset of mustard germination was from 4 to 5 °C (base temperature) and peaked at temperatures from 25 to 30 °C (optimal temperature) and then germination stopped at 40 to 45 °C (maximum or ceiling temperature). Considering that with increasing depth, the percentage and rate of emergence in both species decreased. With increasing flooding period, germination percentage, seedling length and seedling weight of both mustard species decreased.