Effect Of Sex-Related Neighbouring Root On Growth Of Populus Cathayana

Plant-plant interactions play an important roles in organisms adaptation, life history strategy, structure and founction of plant community. However, the study on effect of interaction among plants is rarely, especially on the sex-related neigbouring roots in dioecious plant. Here, Populus cathayana was chosen as a model species in our study, and the effects on growth, morphology, biomass accumulation and distribution, photosynthetic process, root activity, nutritive content among intra- or inter-sexual neighouring roots exsits or absence were investigated, to reveals ecophysiological responses of P. cathayana under sex-related neighbouring root. The main results are follows:1. The morphology growth and biomass of P. cathayana individuals under sex-related neighbouring rootCompared with none neighbouring root treatment, females grown with inter-sexual neighbouring root had a significantly higher height growth(HG), total leaf number(TLN), total leaf areas(TLA), root mass(RM), steam mass(SM), leaf mass(LM), total dry mass(TM), root/shoot ratio(R/S), root/total ratio(RTR); while induced males showed lower HG, basal diameter(BD), RM, SM, LM, TM, R/S; both of treatment with intra-sexual neighbouring root on growth and physiology were no significant difference except BD. The results indicated that the morphology growth and accumulation of biomass of females were promoted, but males were inhibited by inter-sexual neighbouring root. However, intra-sexual neighbouring root do not contribute significantly to morphology growth and accumulation of biomass of females and males.2. The photosynthetic physiology and water use efficiency of P. cathayana individuals under sex-related neighbouring rootCompared with none neighbouring root treatment, females grown in inter-sexual neighbouring root had a significantly greater effective photochemical quantum yield(Yield), intrinsic water use efficiency(WUEi), but lower coefficient of non-photochemical fluorescence quenching(qN), while leaf of males had significantly lower carbon isotope composition(δ13C) under inter-sexual neighbouring root. In addition,female and male of P. cathayana individuals had on significant differences in generally photosynthetic physiology indexes, while females had greater WUEi, δ13C,males had lower WUEi, δ13C under intra-sexual neighbouring root treatment. The results suggest that inter-sexual neighbouring root promote photosynthesis of females,but not act on males. At the same time, inter-sexual neighbouring root enhance water use efficiency of females leaf, but reduce water use efficiency of males. Furthermore,photosynthetic physiology of female and male of P. cathayana individuals were not affected by intra-sexual neighbouring root treatment, but water use efficiency of females were enhanced, while the water use efficiency of males were reduced under intra-sexual neighbouring root treatment.3. The morphology growth and activity root of P. cathayana individuals under sex-related neighbouring rootThe females root grown in inter-sexual neighbouring root possess a significantly greater total length(TL), surface area(SA), total volume(V), total activity area/volum(TAV), morphology indexes of thick or fine root when compared with none neighbouring root treatment, but males had lower values of TL, SA, V,morphology indexes of thick or fine root with inter-sexual neighbouring root. In addition, females had greater trait values of morphology growth and activity in root than did males under inter-sexual neighbouring root treatment. Except TAV,morphology growth and activity of female and male root of P. cathayana individuals had on significant differences under intra-sexual neighbouring root. The results suggest that inter-sexual neighbouring root changed morphological characteristics and physiological of females root, which enhance absorption efficiency of water and nutrient of females root, but inhibit absorption efficiency of water and nutrient of males root. Moreover, morphology growth of female and male root of P. cathayana individuals were not affected by intra-sexual neighbouring root treatment.4. The nutritive content of P. cathayana individuals under sex-related neighbouring rootCompared with none neighbouring root treatment, the females leaf or team grown in inter or intra-sexual neighbouring root had a significantly greater C/N、C/P,but males had lower C、K 、C/N、C/P. On the other hand, under inter or intra-sexual neighbouring root, the root of females had greater C、P、C/N、C/P, while males had lower C/N compared with none neighbouring root treatment. The results suggest that inter- or intra-sexual neighbouring root promote nutrition absorption and biomass accumulation of females, but has an negative effect on nutrition absorption andbiomass accumulation of males.In conclusion, morphology and physiology of female and male of P. cathayana individuals were affected by sex-related neighbouring root. Intra-sexual neighbouring root have positive effect on morphology growth, accumulation of biomass, absorption and utilization of water or nutrient of females; while negative effect on males in those indexes. However, morphology growth, photosynthetic physiology, accumulation of biomass of female and male of P. cathayana individuals were not affected by intra-sexual neighbouring root.