Effects Of Clipping On Asexual Reproduction And Clone Integration Of Leymus Chinensis In Saline-alkali Heterogeneous Environment

Clonal plants are widely distributed in various plant ecosystems,and their unique asexual reproduction and clone integration make them have strong adaptability to the environment of resource heterogeneity,and occupy an important position in grassland ecosystems.Leymus chinensis is a typical rhizomatous clonal plant with strong grazing and saline-alkali tolerance,and it is the dominant plant and excellent pasture in northern China.Due to natural reasons and man-made over-utilization,the degree of desertification and salinization of grassland soil is increasing,and the utilization rate and productivity of grassland are gradually decreasing,which seriously restricts the development of agriculture and animal husbandry in this region.Therefore,the protection and restoration of grassland ecological environment has become a key issue in scientific research and production.In the past,most of the researches on L.chinensis were conducted in homogeneous environment,but there was a lack of related research on the integration and plasticity change between the connected progeny pairs of L.chinensis in heterogeneous environment.In this experiment,the seedling pairs of L.chinensis connected with the same rhizome were taken as the research object,and the soil saline-alkali heterogeneous environment of natural grassland was simulated by pot control experiment.The effects of soil saline-alkali heterogeneity and clipping,biomass allocation and cloning integration of L.chinensis,population asexual reproduction and rhizome expansion and their physiological characteristics were discussed,which provided some experimental basis and theoretical basis for the restoration of grassland ecosystem formed by L.chinensis population and its community in saline-alkali grassland.(1)In the homogeneous saline-alkali-free habitat,clipping reduced the number and area of leaves of L.chinensis,inhibited the above-ground and under-ground growth of L.chinensis,and generally showed under-compensated growth(NC-NC: 1.4112 g,1.4407 g,NC-MC:0.6252 g,0.5078 g,MC-MC: 0.8969g、0.4384g).Photosynthesis was not affected by clipping;When one side has been clipping,the nitrogen in the above-ground part of L.chinensis is transferred to the side without clipping,and when both sides have been clipping,it is transferred to the under-ground part.(2)In the homogeneous saline-alkali habitat,clipping inhibited the above-ground and under-ground growth of L.chinensis,which generally showed the under-compensated growth(NC-NC: 0.7994 g,0.3252 g,NC-MC: 0.6052 g,0.2802 g,MC-MC: 0.7278 g,0.2612g);clipping stimulated the elongation of rhizome and internode,and increased the compensation coefficient of L.chinensis;clipping increased the net photosynthetic rate,transpiration rate and stomatal conductance of under-ground part of L.chinensis,and promoted photosynthesis;cutting increased the under-ground nitrogen accumulation on the clipping side.(3)In the heterogeneous saline-alkali habitat,unilateral clipping increased the biomass of stem,leaf,rhizome and fibrous root of L.chinensis,and promoted the above-ground and under-ground growth of L.chinensis,which showed the overall over-compensation growth(NC-NC: 0.7138 g,0.47035 g,NC-MC: 1.3084 g,1.1052g);The number of sub-plants,rhizome buds,rhizome number and rhizome length of L.chinensis were increased,which was more obvious on the clipping side.The photosynthesis of the clipping side also increased;unilateral clipping reduced the ratio of total nitrogen above-ground/under-ground on the side without clipping,and promoted the accumulation of total phosphorus above-ground and under-ground of L.chinensis.clipping on both sides severely restricted the biomass accumulation and asexual reproduction of L.chinensis(MC-MC: 0.3886 g,0.2006g).Photosynthesis is also inhibited;however,the accumulation of nitrogen in the above-ground part increased.In a word,heterogeneous habitats promote the clonal growth of L.chinensis,increase the biomass accumulation of various organs of L.chinensis plants,promote the asexual reproduction of L.chinensis,and improve the compensatory growth ability of L.chinensis against mowing interference.Clonal integration exists in L.chinensis ramets,and it is more intense under heterogeneous environmental stress.