| Cenchrus pauciflorus is one of the main invasive species in sandy soil in northern China,the invasive region include the east of Inner Mongolia Autonomous Region and the northwest of Liaoning Province.It has a steady diffusion trend in recent years and has seriously impacts on the local development of economic and biodiversity.In this paper,the experimental materials was selected as C.pauciflorus in four habitats in Horqin sandy land to further explore the differences and variations of growth characters under field conditions,and to explore the effects of water,seed burial depth,nitrogen and phosphorus addition on seed germination and seedling growth characters of C.pauciflorus in different habitats through indoor homogeneous planting experiment.To further clarify the invasion mechanism of C.pauciflorus and put forward scientific and effective prevention and control measures for different habitats.In this experiment,the phenotypic plasticity of C.pauciflorus in four habitats were studied by field investigation,and the response of seed germination and seedling growth of C.pauciflorus in four habitats to key abiotic factors were studied by indoor pot homogeneous planting method.The experiment results were as follows:The results of field investigation showed that:1)Habitat had a significant effect on the selected phenotypic variables（P<0.05）,and the relationship between the phenotypic variables of the four habitats was field,sand dune,forest land and grassland;2)The phenotypic variation among populations in the four habitats was not higher than that within populations（P>0.05）,but there were significant differences among different phenotypes in the same habitat（P<0.05）;3)The ratio of stem to leaf,the ratio of root to shoot and the specific gravity of thorn and bract of C.pauciflorus were significantly affected by the habitat（P<0.05）.The ratio of stem to leaf of C.pauciflorus in the field was significantly higher than that in other habitats,and the ratio of root to shoot and the specific gravity of thorn and bract were significantly lower than that in other habitats;4)Habitat had no significant effect on the variation of root shoot ratio（P>0.05）,but had a significant effect on the variation of stem leaf ratio and thorn bud proportion（P<0.05）.The indoor experiment showed that:1)from the same concentration treatment,the germination rate of forest habitat was significantly lower than that of the other three habitats when phosphorus was added 0.25g P·m-2,and there was no significant difference among the other three habitats;There was no significant difference in the germination rate of prickly bud in four habitats（P<0.05）;2)With the increase of nitrogen concentration,the germination rate of the four habitats decreased significantly（P<0.05）;From the same concentration treatment,there was no significant difference in bud germination rate among the four habitats（P>0.05）.3)The germination rates of the four habitats were significantly different in the same seed burial depth treatment（P<0.05）.The mean germination rates of the four habitats increased with the deepening of the depth,and the maximum was at the depth of 4 cm;4)There was significant difference in the germination rate of thorn bud in the four habitats when the water gradient was P4 and P5（P<0.05）.In general,phosphorus was not an important factor for the difference of thorn bud germination in the four habitats;The depth of seed burial is the influencing factor of the difference of thorn bud germination in the four habitats,and the water conditions also affect the thorn bud germination in the four habitats to a certain extent.In terms of seedling growth,1)with the increase of phosphorus addition,the plant height and leaf length of C.pauciflorus seedlings in four habitats increased,and the root length decreased.There was significant difference in plant height between habitats when low and medium phosphorus was added,and there was significant difference in leaf length between habitats when high phosphorus was added.The plant height and leaf length in border and ridge habitat were higher than those in the other three habitats.There were significant differences in root length under low concentration treatment,and the root length in dune habitat was the highest;2)Medium and high concentration nitrogen addition can effectively inhibit the survival of C.pauciflorus seedlings,which may be because the young roots can not bear the physiological drought caused by nitrogen addition;3)There were significant differences in plant height and leaf length among the four habitats,and the plant height and leaf length in border and ridge habitat were the largest;The root length of seedlings in four habitats had significant difference at 0 cm and 6 cm burial depth（P<0.05）,and the root length in forest land was the largest.With the increase of burial depth,plant height,leaf length and root length increased first and then decreased.4)There were significant differences in plant height among the four habitats under different water gradient treatments（P<0.05）,and the plant height in dune habitat was slightly higher than that in the other three habitats.The leaf length of the four habitats had significant difference under P1,P4 and P5 water treatment（P<0.05）,the root length had significant difference under P3,P4 and P5 treatment（P<0.05）,and the root length in dune habitat was the smallest.Cenchrus pauciflorus adapts to different habitat conditions by adjusting phenotype and material distribution strategies.Its nutritional traits,clonal traits,reproductive traits and material distribution have certain habitat plasticity,but there is no significant difference between the variation within the population and between the populations of each functional trait,and the difference between the variation of different traits within each population is statistically significant.The results of homogeneous planting experiment showed that the amount of nitrogen/phosphorus in soil,the burying depth of thorn bud and soil moisture could affect the germination rate and seedling growth of thorn bud of C.pauciflorus to a certain extent.In view of the highly conservative self pollination characteristics of C.pauciflorus,the differences in bud germination rate,seedling growth and functional traits under field conditions between different habitats are likely to be determined by environmental and genetic factors. |
