A Study On?reproductive Ecology Of Allium Wallichii Kunth

The survival and reproduction of a species in a given area is often related to its reproductive characteristics and environmental adaptability.Jiucaiping is the largest wild Allium wallichii Kunth belt in the world,the only wild leek flower reserve in China.In order to explore why the Allium wallichii can form such a large leek flower belt in Jiucaiping,in this study,we investigated the reproductive ecology of?Allium wallichii.In explore of flower attractive mechanism,color and smell were?main research content,The purple(common)and white(rare)flower ?were measured by reflectance spectroscopy and the turn it into bee vision.To detect the scent of Allium wallichii,the roots,stems,leaves,petals,stigma,ovary,nectar,pollen and pedicels were analyzed by gas chromatography;In explore of environmental adaptation differentiation,we compared the differentiation of morphological characteristics between the central and peripheral population,morphological characteristics,ploidy level,species diversity index,flower visitors,seed setting rate,flowering period,nectar and pollen viability of central and marginal populations were observed and detected.In order to compare the changes of morphological characteristics more clearly,in this study,an increasing?rate model(IR)was established to quantify the differentiation differences for traits between the central and peripheral of populations.The?main results were as follows:1.There was a significant difference in the density of population,with plant density of 45.2 individuals / m~2 in the central area and 2.0 individuals / m~2in the peripheral area.The dominance of Allium wallichii in the central area was significantly higher than that in the peripheral area,but the species richness and diversity in this area were significantly lower than that in the peripheral area.It can reproduce by sexual reproduction,apomous reproduction and vegetative reproduction.Apis cerana was the main?pollinators,the single set of bees was 9.918 9±2.783,In the natural state,the pollen number was 50.47±6.99,among which,the pollen of the Allium wallichii accounted for 69.20±2.79 %.The germination rate of the pollen at the sugar concentration of 10% was higher,and the germination rate of the central plants was 37±3.4%,which was significantly higher than that of the peripheral plants at 27±2.4%.The inflorescence is clustered and globular to improve the visual effect,the longer length of the pedicel can effectively increase the surface area of the inflorescence,which greatly enhances the color and odor attraction.The single flowering period is 7-8 days,the inflorescence flowers open in sequence from bottom to top,and the anthers mature in two staggered batches,which can improve the duration of pollen dispersal,reduce self-pollination,and maintain a stable pollination state in the climate changing environment of alpine areas,to improve the reproductive dominance.2.The results for two color reflectance spectroscopies showed the petals and pollen of purple flowers were more prominent in bee vision under the background of green leaves.When the visiting frequency of two flower colors were observed respectively,the visit frequency of purple flower was significantly higher than white flower,but there was no significant difference in single visit frequency;When two colors of flowers were mixed together,the bee give priority to purple flowers,but visit frequency and single visit frequency had no significant difference between two colors.The results of gas chromatography for the analysis of secondary metabolites showed that stems,ovary and pedicels contain a variety of irritating sulfur metabolites,petals,ovary,and nectar contain a variety of secondary metabolites of floral fragrance.So purple flowers were very attractive to bees,and was beneficial to improve the pollination advantage of Allium wallichii.The special pungent smell and floral substances of Allium wallichii may be an important reason for attract bees and had specificity visit flowers.3.The plant characteristics of the central and peripheral of the population are significantly different,?and there is a certain degree of characteristic differentiation,?which is closely related to the selection of pollinators and the impact of survival pressure.The results showed that the reproductive ability of the central plants in the population was significantly improved,?the seed setting rate was significantly higher than that of the peripheral plants,and the pollen quantity and pollen germination rate were significantly higher than that of the peripheral plants.The number of vegetative reproductions,the number of flowers,the height of plants,the size of leaves and stems and other morphological characteristics were significantly higher than those of peripheral plants.The increased ratio(IR)of most flower trait was lower than the lowest IR value of vegetative organs,and the IR value of nectar was even negative,but the IR value of flower number and ramet number were much higher than the highest IR value of vegetative organs.The ploidy of Allium wallichii was also different in different degree,the central plants were mainly tetraploid,and the hexaploid individuals were positively correlated with the plant size.At the peripheral of the population,there was no obvious morphological differentiation,and the plants were mainly diploid and tetraploid,but no hexaploid was found.The frequency of flower visiting(bee)in central population was much higher than that in the peripheral,but there were more species of flower visitors in the peripheral population than in the central population.The difference between the visiting environment and the living environment leads to the difference in the selection pressure of the individuals in the central and the peripheral.Under the fierce reproductive competition and the selection of pollinators in the central area,the reproductive characteristics of Allium wallichii were significantly different,mainly manifested by the large amount of investment and appropriate reduction to some features.?By balancing the reproductive characteristics,the pollination efficiency of the central plants could be greatly improved and their reproductive fitness could be improved.The population peripheral has a low plant density,which is mainly faced with the survival pressure of inter-species competition.The available resources are insufficient,and the resource allocation is skewed to the improvement of survival ability.Therefore,the reproductive ability is relatively weakened due to the shortage of resources,?but the surviving individuals maintain the stability of the population peripheral by gradually accumulating dominant characteristics.