Effects of sand burial and seed processing on stored seed germination and seedling emergence of Pinus sylvestris
Guo Mishan, Wang Qian, Gao Guanglei, Zhao Yuanyuan, Ding Guodong
1. College of Soil and Water Conservation, Key Laboratory of State Forestry Administration on Soil and Water Conservation, Beijing Forestry University, 100083, Beijing, China; 2. Yanchi Ecology Research Station of the Mu Us Desert, 751500, Yanchi, Ningxia, China
[ Background ] Pinus sylvestris var. mongolica is an important species for ecological environment construction in the desertified regions of northern China. There has been declines in P. sylvestris plantations, barrier on regeneration has been the key factor limiting the succession of P. sylvestris plantations. [Methods] To explore the limiting factors for natural regeneration of P. sylvestris plantations, experiments in the laboratory were carried out on the effects of sand burial (depth of 0.25, 0.50, 1.00, 1.50, 2.00 and 3.00 cm in a container simulating the sand land) and seed processing (No-soaking, soaking in 25 -30 ℃ warm water, and soaking in 55 -60 ℃ hot water) on the germination and seedling emergence of P. sylvestris. The seeds were collected from the Yulin of Shaanxi Province, stored at room temperature, 4℃ refrigeration and - 18 ℃ frozen. The data were analyzed by two-way ANOVA. [Results] 1) In range of 0 -3.00 cm, the rate of seed germination and seedling emergence was 68.9% that reached the highest with no sand burial, and decreased with the increase of burial depth, there was about 20% seeds germinated but no seed emerged under 3.00 cm depth. Sand burial caused the germination time increased, the average germination time was only 4 d with no sand burial, the average germination time reached 15 d under 2.00 cm depth. 2) The seeds stored at 4 ℃ were more superior to those at the room temperature and frozen storage of - 18 ℃, for a higher germination and emergence percentage and a shorter emergence time. Low temperature preservation was helpful to increase the seed vigor in the shallow sand burial depth (0 - 1.50 cm), but the different seed corresponded to different germination and emergence of the optimal temperature range. 3 ) The germination quality of seeds soaked in 25 -30 ℃ warm water were superior to those soaked in 55 -60 ℃ hot water and no-soaking, for a higher germination and emergence percentage, emergence rate and a shorter emergence time. Too high soaking temperature inhibited seed germination, the seed germination rate of soaking in 55 -60 ℃ hot water at 1. 50 cm depth was only 0.3% and had a long emergence time as 16 d under 1.50 cm depth. [Conclusion] 4 ℃ storage and 25 - 30 ℃ warm water soaking are appropriate seed treatment for P. sylvestris. The results can be used to provide the references to solve the problem of natural regeneration and provide technical support for the artificial breeding of P. sylvestris plantations.