Impacts Of Nutrient Levels And Interaction Of Neighboring Plants With Different Identities On The Clonal Growth Of Three Plants

In natural habitats,most of plants grow together with other neighboring plants,and it was reported that the difference of the identities of neighboring plants may impact on the growth and reproduction of some plants.This paper aimed to explore the main features of the interactions between the neighboring plants with different identities,and the impacts of different identities of the neighboring plants on the comprehensive characteristics of the clonal growth of Zoysia sinica,Zoysia japonica and Alternanthera philoxeroides under the conditions of different neighbor identities(close kin group,distant kin group and non-kin group),and high or low nutrient levels,as well as total root non-segregation(NS),clone segregation(CS)and ramet segregation(RS).The main results showed below:(1)Under the condition of total root non-segregation,root biomass of Z.sinica in close kin group at lownutrient levels significantly decreased by 75.79%and 61.68%,respectively,compared with the non-kin group and distant kin group,but the aboveground biomass of Z.sinica in close kin group at low nutrient levels decreased by 17.82%and 32.66%,respectively,and in at high nutrient levels,root biomass of Z.sinica in close kin group decreased by 38.13%and 64.39%,respectively,compared with the non-kin group and distant kin group,and the aboveground biomass of Z.sinica in close kin group decreased by 29.59%and 56.61%,and the number of ramets of the clone did not showed differences under two nutrient levels.The performances of Z.japonica was similar to those of Z.sinica at lownutrient level conditions,but in high nutrient level conditions,the biomass of Z.japonica clone in distant kin group reached the minimum,which might resulted from the asymmetry competition from the neighboring plants.A.philoxeroides performed just the opposite to Z.sinica.A.philoxeroides clone reached the maximal root biomass and total plant biomass,when growing with the neighboring plants belonging to the same species,and at the mean time,R/S was significantly greater than that in the condition of A.philoxeroides growing with the neighboring plants belonging to the different species,which implied that root system of A.philoxeroiides tend to compete rather than cooperate with their neighboring plants in this case.(2)Under the condition of clone segregation,root biomass of Z.sinica did not show significant difference between groups,and the leaf biomass reached minimum in close kin groups,and no significant difference of aboveground biomass between the distant kin groups and non-kin groups were found in.With the increase of the nutrient levels,the different part of biomass of Z.sinica clone in all groups increased.The leaf biomass and the aboveground biomass of A.philoxeroides positively correlated with the spacer length between the ramets,respectively,at low nutrient levels.Under the high nutrient levels,the clonal biomass of A.philoxeroides grew with different neighbors did not show significant difference.Root biomass of Z.japonica clone did not show significant differences between groups(close kin group or non-kin group of distant kin group)at low nutrient levels,but leaf biomass,aboveground biomass and total biomass of Z.japonica clone in close kin group reached the maximum.Under the high nutrient level,root biomass of Z.japonica in close kin group was significantly greater than that in the distant kin group and non-kin group,but root biomass did not show significant difference between the distant kin group and non-kin group.(3)Under the condition of ramet root segregation,the biomass of basal,middle and apical part ramets of Z.sinica clone didn't show consistent trends.However,from the points of the overall biomass allocation of Z.sinica,the aboveground biomass between groups were similar at low nutrient levels,but at high nutrient levels,the aboveground biomass in three groups showed that close kin group<non-kin group<distant kin group.Leaf,root and total biomass of A.philoxeroides clone growing together with the neighbor of the same species reached the maximum,but stolon biomass reached the minimum.Under low nutrient levels,the root,leaf and aboveground biomass of Z.japonica clone among different groups did not show differences.Under high nutrient levels,the different parts of biomass of Z.sinica clone in non-kin group were smaller than those in the close kin group and distant kin group.(4)Under the condition of root non-segregation,total biomass of Z.sinica clone in close kin group increased by 62.09%and 20.46%,respectively,compared with the conditions of clone root segregation and ramet root segregation,and also did not decrease the vegetative reproduction in terms of ramet numbers or any other part of biomass,which suggested that the effect of kinship facilitation happened in Z.sinica clone when growing together with the neighbor of the same species,and this phenomenon only appeared under the condition of root non-segregation.On the contrary,under the condition of ramet root segregation,root biomass of A.philoxeroides clone increased by 7526%and 75.99%,respectively,compared with the condition of root non-segregation and clone segregation,and similarly,the total plant biomass of A.philoxeroides increased by 55.69%and 51.92%,respectively,which indicated that segregation of root facilitated the growth of the different parts of A.philoxeroides.Under different conditions,root biomass of Z.japonica clone showed such sequence:non-segregation<clone root segregation<ramet root segregation,which implied that the increase of degree of root segregation facilitated the root biomass of Z.japonica.