The Reproductive Strategies Of Androdioecious Species Acer Tegmentosum Maxi

The breeding methods and mating strategies of flowering plants are very complex,and researching on the reproductive characteristics is helpful to explain the plant breeding mechanism.Androdioecy is a rare sexual dimorphic reproductive system,characterized by the co-existence of hermaphrodites and males in the same reproductive population.Investigations into evolutionary and maintenance mechanism revealed that most of these species turned out to be functional dioecious species.Therefore,when identifying the plant mating system type,we must consider the function of their reproductive organs.The theory of plant life-history is largely concerned with optimal resource allocation between male and female functions.For sexual dimorphism species,the reproductive resource allocation patterns are usually different between genders,which would contribute to gender-related vegetative growth rate and biomass allocation patterns,and these are the focus of plant breeding characteristics study.In this study,we carried out the four-year monitoring observation of an androdioecious species Acer tegmentosum in the coniferous and broad-leaved mixed forest at the Jiaohe experimental forest in Jilin province.We mainly studied the sex ratio and spatial distribution pattern,the breeding system,the reproductive resources allocation patterns and its effects,the allometric biomass models and the stoichiometry patterns between male and hermaphrodite A.tegmentosum.The main results are as follows:1.We analyzed the population sex ratios,spatial distribution patterns of A.tegmentosum in near-mature forest and mature forest,as well as the spatial associations between genders.The results showed that there are more males than hermaphrodites in the two plots,and the sex ratio deviate significantly from the expected ratio of 1:1.The results of Ripley’s L analyses indicate that males and hermaphrodites are both distributed clustered.In the near-matured forest,the relationship between genders was negatively correlated.We found typical sex separation between sexes in our study area.2.We carried out both field observation and control experiment to research on the function of reproductive organs.Both genders of A.tegmentosum blossom in May,with racemes of green flowers.For hermaphrodites,the fruits come with dipterous appearance and change from green to yellowish-brown when ripe in September.Compared with hermaphrodite flowers,male flowers are bigger in size,and there exists spatial separation between stigma and anther.The P/O is about 4216 and OCI 4,so the mating system type is a specific out-crossing,requiring pollinators.The results of control experiment reveals that the reproductive type is sexual reproduction.The anthers of perfect flowers are indehiscent or barren,i.e.,A.tegmentosum is functionally dioecious.3.Since 2014,we examined the reproductive allocation patterns between genders for three consecutive years.Hermaphrodites showed a higher value of reproductive biomass and reproductive ratio than males.While males showed higher biomass in vegetative biomass of leaf and new-born branches at level 2 and level 3 branches level,but there was no significantly differences at plant level.We analyzed the effects of gender,soil environment,light environment,neighborhood competition and individual size on reproductive ratio.The results showed that genders had a significant effect on the reproductive ratio,which was positively correlated with sex for hermaphrodites.In terms of habitat factors,the content of soil P and soil K have a positive effect for the reproductive ratios of males,while soil organic matter soil N negative.Competition by all trees,soil moister,soil P and soil K showed negative effect,while soil N showed positive effect for the reproductive ratios of hermaphrodites.4.We present biomass allocation patterns and relationships between components of the androdioecious A.tegmentosum.The objectives of this study were to examine how gender affect the biomass structure of androdioecious species and how the gender-related reproductive efforts affect the allometric relationships.We harvested 31 hermaphrodite and 29 male A.tegmentosum trees and opted for diameter at breast height,tree height and crown length as the independent variables and various biomass components as the dependent variables.Five types of function were used to model allometry equations.Biomass allocation between genders was different,and the best biomass model for each biomass component varies between genders.Males have a higher investment in foliage and coarse root biomass than hermaphrodites,and hermaphrodites invested more in reproduction than males.Biomass equations are strongly gender-related.Males tended to invest a larger fraction of the vegetative biomass into leaves and coarse roots.5.Altogether 31 hermaphrodites and 29 male plants were harvested and samples of leaves,current-year shoots,branches and coarse roots were analyzed to explore gender differences in C,N and P concentrations of these four components.The nitrogen to phosphorus relationship of each component was examined using SMA estimates.Males had significantly greater amounts of leaf and coarse root dry matter content than hermaphrodites.C,N and P stoichiometry differed significantly between genders,especially in the newly emerging vegetative components(leaves and shoots).Males had higher C/N and C/P ratios in current-year shoots and lower C/P ratios in leaves and branches.Hermaphrodites had higher N/P ratios in the leaves and branches.Males had higher rates of increase in leaf P content than hermaphrodites.This study suggests that stoichiometry patterns may be significantly affected by gender.