Effects Of Soil Coarsening On Growth And Reproduction Of Setaria Glauca(l.)beauv. And Chloris Virgata

The grassland is an important ecological barrier and production base of animal husbandry, soil degraded significantly under the irrational land use and climate change. Grassland had a soil characteristic of soil coarsening by reducing of soil fine particle, where soil degraded significantly. Soil coarsening changes the plant growth and reproduction. These transformations were formed by plant and the environment, which not only reflected the influence of environmental change upon plants, but also reflected the ability that plant individual adapt to environmental variety. This research studied the quantitative effects of soil coarsening on growth characteristics and reproductive strategy of the Setaria glauca(L.) Beauv. and Chloris virgata,which widely distributed in the area of Zhang gutai by compounding different soil with diverse coarse degree. Through the analysis of morphology characteristics and resource allocation in the different soil with diverse coarse degree, to gain further insight into growth and reproductive strategies of two kinds of plants under soil coarsening; to provides a theoretical basis for guiding the vegetation practice, curbing trend of soil environmental deterioration, and using plant properties to improve the degraded sandy environment. And also to provides necessary parameter estimation and model validation to accurately analyse and predict future changes in growth and reproductive strategy of Setaria glauca(L.) Beauv. and Chloris virgata. The results showed that:(1) The plant height, root length, above and below ground biomass of Setaria glauca(L.) Beauv. and Chloris virgata all had a significant difference in the different soil with diverse coarse degree, were all negatively correlated with the index of soil coarsening. Means that soil coarsening made two species become smaller in order to reduce the survival risk, was also an ecological adaptation of two species of plant on soil coarsening environment.(2) the biomass accumulation of Setaria glauca(L.) Beauv. and Chloris virgata were mainly distribute on the part of above ground. Root shoot ratio of two species had a significant difference in the different soil with diverse coarse degree, and increased with the increase of index of soil coarsening. When environment steadily deteriorated, underground biomass of two species accumulation faster than aboveground biomass, in order to obtain more resources from soil. Means that two species have a growth strategy that can appropriately mediate root shoot ratio to adjust to the environment(3) Setaria glauca(L.) Beauv. and Chloris virgata had a similar relationship between aboveground and belowground biomass in different soil, this relationship was characterized by allometry model.(4) Setaria glauca(L.) Beauv. and Chloris virgata ear length and ear biomass had a significant difference in the different soil with diverse coarse degree, and had a significant negative correlation with index of soil coarsening. This difference is the result of the interaction between two species and environment.(5) Setaria glauca(L.) Beauv. and Chloris virgata reproductive allocation had a significant difference in the different soil with diverse coarse degree, and increased with the increase of the degree of soil coarsening. To illustrate that two species can appropriately mediate reproductive allocation to adjust to the environment.(6) Setaria glauca(L.) Beauv. and Chloris virgata reproductive investment(ear biomass) were positive correlated with aboveground biomass in all of the different soil, but reproductive allocation and individual size did not show a fixed pattern. This result showed that reproductive investment entirely followed the size-dependent pattern, but reproductive allocation showed lower level of following the size-dependent pattern.(7) Setaria glauca(L.) Beauv. and Chloris virgata reproductive allocation was positively correlated with reproductive investment in all of the different soil. Setaria glauca(L.) Beauv. reproductive allocation in the higher degree of soil coarsening showed higher level of following the size-dependent pattern than lower area. Chloris virgata had no similar change trend.(8) Setaria glauca(L.) Beauv. and Chloris virgata branch number, lateral branch number, leaf number and the ear number were no significant differences in different soil with diverse coarse degree. This is probably because of the interference caused by the interaction of environmental factors and community coupling,may also because of soil coarsening is not the impact factor of these indexes.(9) Two species had similar changing trends of growth and reproductive characteristics and reproductive strategies in the different soil with diverse coarse degree,but there were some differences between the extent of the changes.