Physiological and biochemical characteristics of Larix olgensis and L. gmelini seeds under ultra-dry treatment

Seeds were dried to 5% moisture content (MC) or less by the silica gel method. After ultra-drying (before and after aging), germination energy (GE), germination percent (GP), germination index (GI), vigor index (VI), relative conductivity (RC), dehydrogenase (DH) and isocitratelyase (ICL) activity were investigated. The results show that GE, GP, GI, VI of ultra-dried L. olgensis seeds with 3.02% MC maintain a relatively high level before and after aging. Under 3.02% MC, VI before aging, GP, GI, VI, DH and ICL activities after aging are significantly higher, and RC is lower than those of seeds without ultra-drying treatment (natural-dry). This implies that 3.02% MC is a feasible seed moisture content during storage for L. olgensis. Ultra-dried L. gmelini seeds with 2.63% MC before and after aging keep higher germination vigor, with significant higher GP, GI, VI before aging, and GE, GP, GI, VI after aging than those of naturally dried seeds. Their DH and ICL activities are significantly higher, and RC is lower after aging compared with naturally dried seeds. L. gmelini seeds with 2.63% MC show stronger anti-aging ability than those with others levels of MC, therefore, 2.63% is feasible seed moisture content during storage for L. gmelini.