Growing Development and Physiological Characteristics of Seeds Harvested Different Days after Pollination and Their 7-day Seedlings of Two Yellow-Seeded Cultivars of Brassica napus L.

This study aimed to understand the growing development and physiological characteristics of seeds harvested different days after pollination and the seedlings emerged from the seeds of yellow-seeded Brassica napus L..Two yellow-seeded cultivars‘Hongyuan 558’and‘Qinyou 806’were selected in this study,and 50 seeds were collected 30,35,and 40 d after pollination,respectively.The seeds were weighed and placed on filter paper for hydroponic experiments.The seed germination rate was determined 3-5 d later.The physiological indicators including superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)activities and malondialdehyde(MDA)content were measured for the seeds harvested different days after pollination and the 7-day-seedlings emerged from the seeds.The results showed that the seed dry weights and germination rates of both‘Qinyou 806’and‘Hongyuan 558’increased as the days after pollination increased,especially 30-35 d after pollination.The germination rate and dry and fresh weights of the seeds showed no significant differences between the two cultivars,and almost all the seeds germinated 40 d after pollination.As the days after pollination increased,the SOD activities in the seeds of both cultivars first increased and then decreased,reaching their peaks 35 d after pollination,which may be related to encountering adverse stress.The POD activity in the seeds of‘Qinyou 806’kept declining,and that of‘Hongyuan 558’first increased and then decreased,which may be related to the antioxidant mechanism and adaptive regulation.The CAT activities in the seeds of both cultivars first decreased and then increased.The MDA content in the seeds of‘Qinyou 806’first decreased and then increased,while that of‘Hongyuan 558’kept reducing and was the highest in the seeds 30 d after pollination,which indicated‘Hongyuan 558’was mildly affected by the environment and had strong resistance.The activities of SOD and POD in the seedlings of two cultivars that were emerged from the seeds 35-40 d after pollination became weakened,which may be related to their exposure to stress.The CAT activity in the seedlings of‘Hongyuan 558’was generally higher than that of‘Qinyou 806’,indicating that‘Hongyuan 558’had stronger stress resistance.The MDA content in the seedlings emerged from the seeds 35-40 d after pollination showed a decreasing trend,indicating that the seedlings emerged from the seeds harvested at this stage had mild cell membrane damage and enhanced stress resistance.In conclusion,‘Hongyuan 558’had strong environmental adaptability and stress resistance.