Sand Priming Promotes Seed Germination, Respiratory Metabolism and Antioxidant Capacity of <i>Pinus massoniana</i> Lamb.

The validity to promote seed vigor of sand priming had been reported; however, its feasibility in pine seeds remained unknown. In this study, Masson pine (Pinus massoniana Lamb.) seeds of three varieties were used to investigate the effect of sand priming on seed germination, respiratory metabolism and antioxidant capacity. Seeds treated with hydrated sand, about 5% moisture over 2 day, were employed as the priming group with non-primed seeds as the control. The germination test and field test showed that the germination rate, germination potential, vigor index and field emergence rate of sand-primed seeds were significantly enhanced by 8.3~12.3%, 3.9~11.5%, 40.4~72.3% and 5.8~8.9% compared to non-primed seeds. The oxygen-sensing test indicated that sand priming accelerated seed respiration. Besides these, antioxidant enzyme activities and endogenous GA1 and IAA are also enhanced after sand-priming treatment. Furthermore, the variation tendency of gene expression of GID1, POD and SDH was in line with the physiological parameters. Based on the results, the regulatory mechanism of germination promotion of the Masson pine by sand priming was clarified. Sand priming might promote respiratory metabolism, endogenous hormones and antioxidant capacity through influencing the related gene expression, which would have a conjoint promotion on the seed germination of Pinus massoniana