|其他摘要||Leguminosae is an important group of plants in arid area of Northwest China, ephemeral and ephemeroid species also a special group in Jungar Basin in Xinjiang. In this research, 18 arid Leguminosae species in Pappilionoideae and Cassia tora L.in Caesalpineae as control, and Carex physodes (Cyperaceae) which is spring ephemeroid rhizomatous sedge were chosen as research material. The dormancy breaking mechanism and the adaptation strategyof 19 Leguminosae species were investigated by adopting the combined technical design of interior control experiment, site condition-simulation and field observation. Also, the seed-set pattern, seed dispersal characteristics, seed germination and its ecological effects in natural community of the C. physodes were investigated to understand the ecological adaptation strategy of this species. The main results and discussions are as follows:
1. The seeds of 19 Leguminosae species had low soil moisture (4.04±0.6%-11.24±0.5%) but high viability (>90%), all the species had orthodox seeds. According to the storage behavior and germination characteristics, the seeds were classified to three types including: seeds with no dormancy, seeds with high level of physical dormancy and low level of no dormancy and seeds with high level of physical dormancy and low level of physiological dormancy.
2. Low temperature treatment significantly increased seed germination Glycyrrhiza uralensis Fisch and G. glabra L. However, it didn’t affect the dormancy breaking of Ammodendron bifolium (Pall.) Yakovl.), Eremosparton songoricum (Litv.) Vass.), Sophora alopecuroides Linn., Halimodendron halodendron (Pall.), Sphaerophysa salsula (Pall.) DC.) and Astragalus lehmannianus Bunge. H2SO4 scarification treatments were effective to break dormancy (>80%). The untreated seeds of tropical and subtropical control species of C. toraand arid land species intemperate zone as G. uralensis, S. alopecuroides, A. bifolium, Melilotus suaveolens Ledeb. and Oxytropis gorbunovii did not germinated.
3. According to the response to dry heat and wet heat treatment under summer high temperatures, there were four different types of seedsos 11 species, including: temperature-insensitive, wet-heat sensitive, dry-heat sensitive and both dry/wet-heat sensitive.
4. The summer extreme temperatures in arid area are effective to release seed physical dormancy, however rare precipitation is the main inhibitor of seed germination. The seeds of S. salsula, S. alopecuroides, A. bifolium, E. songoricum and control species of C. toraall belong to the wet-heat sensitive type.
5. The control study of different temperature and water conditions at room showed that: the seeds of the G. glabra and A. bifolium had no significant sensitive cycling to the monthly mean temperatures and moisture condition of field; Seeds of S. alopecuroides, S. salsula and E. songoricum were belonging to sensitive type, the sensitivity of those seeds at dry storage was higher than those at wet storage.
6. The effect of burial depths and burial periods to the dormancy breaking and germination of seeds were different, depending on species, the dormancy breaking percentage of seeds of species was significant difference at different burial depths.
7. The seed-set of C. physodes at different positions of sand dune were heterogeneous, the lowest seed-set was 64.01±2.67% and the highest was 86.96±2.40%.
8. The vascular pericarps of utricles are dispersed by wind and occasionally occurred rainfall in the study area. The pericarp has more strong dispersal ability than that seeds, the different dispersal ability of utricles and seeds have heterogeneousecological vitality.
9. No freshly matured seeds germinated over a range of temperature regimes after treatment with GA3, dry storage or removal of part of the endosperm. However, the higher percentage of seed germination occurred after removal of the pericarp and the chemical scarification. The optimal germination temperatures were ranged from 25/10 ℃ to 35/20 ℃. Cold stratification and sand burial significantly increased seed germination of C. physodes (<40%), indicated that the seeds had no marked seasonal dormancy, and part of the seeds had nondeep PD and other parts had intermediate PD.
10. The pericarp and seed coat inhibitor was a critical factor which has strong mechanical resistance to germination. The pericarp of C. physodes has inhibitory effect on the seed germination of C. physodes, but the pericarp of C. physodes has different effects on seed germination of associated species.|