Effects of nitrogen addition on clonal integration between mother and daughter ramets of Moso bamboo: a ^(13)C-CO_(2) pulse labeling study

Resource sharing among connected ramets(i.e.clonal integration)is one of the distinct traits of clonal plants.Clonal integration confers Moso bamboo(Phyllostachys pubescens)a strong adaptability to different environmental conditions.But the mechanisms of how clonal integration makes Moso bamboo has better performance are still poorly understood.In this study,acropetal and basipetal translocation of photosynthates between Moso bamboo ramets were analyzed separately to investigate how clonal fragments obtain higher benefits under heterogeneous N conditions.Clonal fragments of Moso bamboo consisting of two interconnected mother–daughter ramets were used,each of the ramets was subjected to either with or without N addition.The acropetal and basipetal translocation of ^(13)C-photosynthates was separated via single-ramet ^(13)C-CO_(2)-labeling.Mother ramets translocated more ^(13)C-photosynthates to daughter ramets with N addition,and the translocation of ^(13)C-photosynthates to mother ramets was more pronounced when daughter ramets were treated with N addition.The ^(13)C-photosynthates that were translocated from mother ramets without and with N addition were mainly invested in the leaves and roots of daughter ramets with N addition,from daughter ramets with N addition were mainly invested in the leaves and roots of mother ramets with and without N addition,respectively.These results suggest that mother ramets preferentially invest more resources in nutrient-rich daughter ramets,and that daughter ramets serve as efficient resource acquisition sites to specialize in acquiring abundant resources based on the resource conditions of mother ramets.Clonal plants can improve their resource acquisition efficiency and maximize the overall performance in this way.

Effect of N and P fertilization on the allocation and fixation of photosynthesized carbon in paddy soil

Potted rice seedlings independently treated with N,P,and NP were continuously^(13)CO_(2) labeled to investigated the influence of N and P application on the contribution of photosynthesized C to the rhizosphere versus bulk soil and particulate organic matter(POM)versus mineral fraction(MIN).N and NP enhanced net assimilated^(13)C on day 14(D14),with maximum C assimilation occurring on day 22(D22)under NP.Aboveground biomass retained more^(13)C than belowground biomass for all treatments.^(13)C incorporation into the rhizosphere exceeded that in bulk soil,with the maximum(6-10%)found under N addition.Newly assimilated^(13)incorporated into POM increased in the rhizosphere under N and NP conditions,whereas MIN remained largely unaffected.^(13)C-MBC proportion in the total microbial biomass C(MBC)pool revealed that N and NP stimulated microbial activity to a greater degree than P.The main portion of^(13)C in the rhizosphere and bulk soil was found in POM on D14,which decreased over time due to microbial utilization.Contrastingly,root-derived ^(13)C in the MIN remained unchanged between sampling days,which indicates that the stabilization of rhizodeposits in this fraction might be the potential mechanism underlying SOM sequestration in paddy soils.