The Reproductive Characteristics Of Two-type Flowers Of Viola And Its Reproductive Response To Heterogeneous Habitats

The genus Viola(Volia L.) belongs to the Violaceae family.It is an annual to perennial low herbaceous plant.It is widely distributed and has small differences among species.It has very similar morphology and many species.Most botanists Think of it as a difficult group to identify.Most species of Viola have a unique bimorphic hybrid breeding system.Generally,flowering and fertilized open flowers(Chasmogamous flowers,CH)can be produced in early spring,while closed flowers(Cleistogamous flowers,CL)are fertilized in late spring.It didn't form until the end of autumn.Some species produce CH flowers in spring and summer,but can also form open flowers(CH) and closed flowers(CL) in autumn.This type of breeding system is a good experimental material for studying plant reproduction strategies.The key component of plant life history is reproduction,which is an important way for plants to reproduce offspring and achieve population renewal.The reproduction strategy of Viola plants will change accordingly with changes in the environment.In different environments,plants can improve their adaptability to the environment by changing their own reproduction strategies to achieve adaptability to survival,growth and reproduction.Final goal.Viola plants are the most suitable experimental materials to explore the plasticity of plant reproduction strategies in heterogeneous habitats.This paper takes Viola plants in eastern Liaoning as the research object,and studies the number of CH flowers and CL flowers in heterogeneous habitats and the plasticity of reproduction strategies.The research first examined the breeding system of experimental species in natural habitats,counted the reproduction contribution of the dimorphic flowers,recorded the developmental processes related to reproduction,such as flowering phenology and the comprehensive characteristics of the floral part,and especially tested the experimental species in four different types.The changes in the number,seed setting rate,and reproduction contribution of the dimorphic flowers in the habitat are used as the reproduction strategy for dealing with heterogeneous habitats.The research goal is to reveal how the reproduction strategy of the dimorphic flowers of Viola is in a heterogeneous habitat.Next,improve its ecological adaptability through its plasticity,and provide more experimental data support for further understanding of the maintenance mechanism of the dimorphic flower in the mixed breeding system.This study drew the following five main research conclusions:(1)Open flowers(CH)bloom from the end of March to the end of May.Some species will produce a small number of CH flowers from mid-September to the end of October.Due to the obvious environmental impact,the flowering period will also change with the environment,generally lasting 21 to 38 days.The average single flowering period of each flower is 6-12 days.Most of the plants studied can produce 4 to 19 CH flowers during the entire flowering period,with fruit setting rates ranging from 13.7% to 23.9%,and seed setting rates ranging from 42.2% to 58.9%.The fruit setting and seed setting rates are relatively low,except for oriental pansy.Vegetables,Northeastern Viola and Early-opening Viola CH flowers have many fruit fruits,and the seed setting rate is as high as 66.0%?76.5%.The Oriental Viola has no occluded flowers,but the CH flower has a high seed setting rate and fruit setting rate,which makes up for the seeds produced by the lack of occluded flowers and ensures population reproduction.However,the CH flowers of Northeast Viola and Early-opening Viola have a much higher seed setting rate and fruit setting rate than most of their species,indicating that they adopt two reproduction modes in order to adapt to a more complex environment for population reproduction.This is because CH flowers in Viola are typical entomophilous flowers,which rely on insect pollination during flowering and fruiting.Due to the low temperature and variable climate in early spring,the pollination of insects is affected,which often leads to pollen restrictions in the reproduction of CH flowers.In order to cope with the restriction of pollination caused by such habitat conditions,Viola plants often increase the success rate of pollination by extending flower life.(2)CL flowers of the Viola genus generally begin to form at the end of April or May,and can bloom until the end of October.Some types of CL flowers can last until the plants wither,and each plant can produce 20 to 34 CL flowers.CL flowers are completely closed flowers for pollination,which makes its fruit-setting rate as high as83.9%-95.5%,and its fruit-setting rate can reach 85.7%-95.0%.Its fruit-setting rate and seed-setting rate are much higher than those of CH flowers,indicating that Most of the seeds of Viola plants are produced by closed flowers(CL).(3)The pollen ovule ratio(P/O)of CH flowers of Viola is about 413.5?1019.3.According to the standard of Cruden(1977),it is in the range of 244.7?2588.0.The type of breeding system is defined as facultative outcross.The pollen ovule ratio(P/O)of CL flowers of Viola is between 3.6 and 7.8.According to the standard of Cruden(1977),it is between 2.7 and 5.4.Most of them can be judged for breeding within this range.The system type is closed flower fertilization,which is consistent with the observation of flower morphology.There is no significant difference in the morphology of the seeds produced by the two flower types of Viola,but the 100-seed weight of open flower(CH) seeds and closed flower(CL)seeds has a significant difference,and the quality of open flower(CH)seeds is better.(4)Viola plants can improve their adaptability by changing their reproduction strategies in heterogeneous habitats.In habitats with better nutrient conditions,CH flowers bloom more,with 1.2-2.4 more flowers,CL flowers bloom better,with 1.3-3.0more flowers;in arid habitats,CH flowers bloom less,with 1.2 fewer flowers.?1.8,CL flowers are also poorly blooming,0.4?3.1 less;CH flowers bloom relatively less in a poorly illuminated habitat,0.4?0.8 less,CL flowers bloom relatively more,more2.1?2.8 flowers.Therefore,in a habitat with better nutrient conditions,the plants grow well and the CH flowers bloom more,but the CL flowers appear later,more flowers bloom in the early stage of flowering,and fewer flowers bloom in the later stage,indicating that under better nutrient conditions,it will Promote the plant to produce more CH flowers,which in turn makes the offspring produce more individuals and the genetic diversity is richer;in a habitat with insufficient light,the number of CL flowers blooms and the number of CH flowers blooms,indicating Illumination conditions affect the formation and ratio of the two types of flowers,as well as the genetic structure of the offspring populations;in a suitable arid habitat,individual plant growth is restricted,the number of CH flowers is reduced,and the flowering time is delayed,while the number of CL flowers is not obvious The decrease,and CL flowers appeared earlier than the normal control habitat,indicating that water conditions will also affect the appearance time and number of the two types of flowers,and will make CL flowers more individuals in the offspring.There is no significant difference in the seed morphology produced by the two types of flowers of Viola,but the 100-seed weight and germination rate of open flower(CH)seeds are higher than that of closed flower(CL) seeds(p<0.05),and open flower(CH)) The seed quality is better,so the suitability of CH flowers is higher than that of CL flowers.