| The study of plant reproductive ecology is a hot topic in the field of ecology.The study of plant reproductive system,pollination ecology,reproductive allocation and investment plays an important role in the cultivation and utilization of plants and the understanding of evolutionary process.The research on flower morphology and pollination system can objectively understand the characteristics of flower and its evolutionary driving force.Ziziphus jujuba var.spinosa is a kind of soil and water conservation species,which can prevent wind and fix sand,keep water and has important economic value.At present,the research on it mainly focuses on the extraction of chemical components,the exploration of pharmacological effects,and the research on reproduction.In this paper,we studied the flowering biology,pollination ecology and breeding system of Z jujuba var.spinosa by studying the reproductive ecology of Z jujuba var.spinosa by soil and water conservation,using phenological measurement,observation of visiting insects and artificial pollination.The adaptive significance of the floral characteristics of Z jujuba var.spinosa dates,its own reproductive strategies,and the mutual adaptation of pollinating insects and Z jujuba var.spinosa dates were discussed,which provided theoretical support for understanding the evolution and cultivation of Z.jujuba var.spinosa dates.The study found that Z jujuba var.spinosa blooms once a year,the single flowering period is about 5-6 days,and the population flowering period is from the end of May to the beginning of July.The bloom of flowers is affected by the environment.The south of the plant blooms earlier than the north of the plant,and the sunny day opens earlier than the rainy weather.The flower characteristics of Z jujuba var.spinosa are herkogamy and dichogamy,both of which tend to make Z jujuba var.spinosa cross pollinated and the flower characteristics adapt to the visiting insects.There is also a slow movement of stamens in Z.jujuba var.spinosa.It is speculated that it may not be to promote self-cross,but to promote cross,so that its reproduction can be guaranteed.There are about 40 species of flower-visiting insects on Z jujuba var.spinosa,which are divided into 5 major orders.Hymenoptera accounts for the most(45%),followed by Diptera(35%),Coleoptera(10%),and hemiptera and scale Lepidoptera accounted for the least proportion,5%respectively.It was found that the peak frequency of visiting flowers of Z jujuba var.spinosa occurred in the period of high nectar secretion and sugar content.There are many types of flower-visiting insects on Z jujuba var.spinosa,with the largest x number of Bibionidae,and due to its large amount of flooding,the number and types of other flower-visiting insects have been greatly reduced.There are no significant differences in the time spent on visits between Chaetididae and Chalcididae,but they are different from Eurytomidae,Ichneumonidae,Tachinidae,Calliphoridae,Sarcophagidae,Apidae,Sphecidae,Coccinellidae,Syrphidae,Formicidae and Tenthredinidae are all significantly different.The visit time of Bibionidae also varies greatly.In addition,there is no significant difference in flight time of insects from one flower to another in different families,and individual individuals(such as Bibionidae,Syrphidae)have large differences in flight time.The pollen germination rate gradually increased from the bud splitting period,and reached the highest during the petal separation period,and then decreased.By calculating the pollen ovule ratio(P/O)and outcrossing index,we found that the mating system of Ziziphus jujuba var.spinosa was mainly heterozygous,some of them were self-compatible and needed pollinators;the fruit setting rate of natural pollination is lower(2%),which may have some limiting factors.However,the artificial pollination of adjacent flowers and cross flowers did not significantly increase the fruit setting rate,which indicated that Ziziphus jujuba var.spinosa had no pollen limitation,there might be resource limitation or fruit was eaten.The fruit setting rate of artificial emasculation and bagging was 0,which indicated that there was no apomixis.The fruit setting rate of artificial self-pollination treatment and natural self-pollination treatment are also 0,indicating that there is no spontaneous self-pollination.The size of seeds may be related to the N content,soil moisture content and canopy density of the plot.The greater the canopy density,the larger the seed;the higher the soil moisture content,the smaller the seed;the larger the nutrient,the larger the seed.The soil moisture content of the sample plot may be an important environmental factor affecting the growth of the seedlings of the future generations,and the light may also have a negative correlation effect,which has some trade-off countermeasures. |
