Effects Of Clonal Integration On Nitrogen Redistribution Among Interconnected Ramets Of Glechoma Longituba

In natural habitats,the essential resources for plant growth are heterogeneously distributed in space.Clonal integration can significantly improve the above-ground community biomass in environments with heterogeneous nitrogen.However,no experiment conducted to underlie the mechanisms of this phenomenon.Nitrogen is an important element for plant growth,and play an important role in photosynthesis.Nitrogen can be redistributed among connected ramets and released into different?recipient?patches.Therefore,we hypothesized that nitrogen can be redistributed among interconnected ramets,released into different?recipient?patches and subsequently used by neighbor plants in the recipient patches.This may significantly improve photosynthetic variables(P_max,V_cmax and Jmax)and leaf chemical properties?such as nitrogen content and allocation of nitrogen to the photosynthetic machinery?,thereby increasing the above-ground community biomass.To test these hypotheses and to understand the effect of patch contrast and distance on clonal integration,we conduct the experiment in which connected and disconnected?target?ramet pairs of Glechoma longituba were grown under in three nitrogen-patch contrast conditions: no?control?,low and high contrast and with three transportation distance: neighbor,spacer and remote.The effects of clonal integration on the photosynthetic variables(P_max,V_cmax and Jmax),leaf chemical properties?such as nitrogen content and allocation of nitrogen to the photosynthetic machinery?and biomass accumulation of connected and disconnected ramets were investigated.We have obtained the following results:1)Nitrogen can be redistributed among interconnected ramets and released into different?recipient?nitrogen-patches through clonal integration.As a result,clonal integration significantly improved photosynthetic variables(P_max?V_cmax and Jmax)and leaf chemical properties?such as nitrogen content and chlorophyll content?.The increased nitrogen content in the photosynthetic machinery resulted in a higher resource capture ability and nitrogen utilization efficiency in the target ramets and connected ramets?neighbor and spacer connected ramets?,and the biomass accumulation of the ramets and target plants.2)Only remote connected ramet in high contrast treatment significantly showed higher photosynthetic variables(P_max ? V_cmax and Jmax)and leaf chemical properties?such as nitrogen content and chlorophyll content?than remote connected ramet in control treatment.Photosynthetic variables,leaf chemical properties and biomass accumulation of target ramets significantly improved in high contrast treatment than target ramets in low contrast treatment.These result suggest that with the enhancement of nitrogen-patche contrast,the clonal integration intensity and range are correspondingly enhanced.3)Further distance had smaller integration in photosynthetic variables(P_max?V_cmax and Jmax),leaf chemical properties?nitrogen utilization efficiency?.But within a certain distance range,further distance had greater integration in leaf nitrogen content and chlorophyll content.These results suggest the effect of clonal integration on different leaf traits may be different.Clonal integration promoting the allocation of nitrogen to the photosynthetic machinery of connected ramets and target ramets may increase the photosynthetic variables which help enchance the aboveground community biomass.Therefore,our hypotheses were supported,which will help to understand the mechanism of the clonal life history traits on the ecosystem function and lead to a deep understanding in context of adaptation of clonal integration to heterogeneous environment.