[Variation of dormancy characteristic of different Pinus bungeana seed sources]

Studies on the dormancy characteristics of Pinus bungeana seeds from 7 representative seed sources show that the difference of water permeability of seed capsule was very significant among seed sources. The seeds from northern part of distribution area had a much higher water permeability than from the south. According to water permeability, the seven seed sources were divided into 2 geographical groups, with Qinling Mountain as the division line. The difference of seed ventilation was caused firstly by outer seed capsule, and secondly by inner one. The variation of permeability had a similar trend with the ventilation. The inhibition ability of seed extracts was significantly different among different seed sources, which was increased with the concentration of seed extracts. Based on the inhibition ability of extracts from seed capsule and endosperm, the seven seed sources were divided into 2 and 3 geographical groups, respectively. The germination capacity decreased with increasing latitude, and seeds with poor germination capacity took relatively more time for germination. All population groups based on different division criteria showed such a character, i.e., the difference of seed characteristics was more significant among groups than in same group, and the distance of seed source was longer among groups than in a group. The difference of dormancy characteristics of different P. bungeana seed sources was the result of interaction between climatic and geographical factors.