Effects Of Morphological Changes On Seed Setting And Seed Quality Of Viola Philippica

Viola philippica is a kind of garden ground cover plant with excellent ornamental traits.The transformation ofthe plants flower morphology lead to the uniqueness of its breeding system.it can form chasmogamous(CH)flowers with flowering and fertilization,while in summer and autumn it can form cleistogamous(CL)flowers,which is a good material for the application of garden green space.In this study,the purple flower Ding is used as the research object to compare the flowering phenology,floral syndrome,reproductive system,seed setting characteristics and seed germination characteristics of CH and Cl flowers revealing the change of flower morphology on the breeding system and seed biology,so as to provide a reference for landscape diversity of garden green land.The main results are as follows:(1)There are two different forms of flowers in Viola philippica,the spring flowers are chasmogany flowers,and the from mid April to late April,flowering phase is short,showing a concentrated flowering mode.CH flowers have petals purple,5 petals,5 calyx,and 2 lower stamens dorsal base has obvious nectary glands and extends into the distance formed by petals,style knees,and the anther grows around the ovary.In summer and autumn,the flower is cleistogamy flower,and the flowering phase lasts from the beginning of May to the beginning of September,showing a continuous flowering mode.CL flowers have no petals,sepals wrap around stamens,styles shrink.(2)There are 7053 pollen grains per flower in CH flower,P/O value is between 173.32-204.49;The CL flowers have an average pollen grains of 179.2 per flowers,and the P/O value is between 4.46-5.95.The combined outcrossing index(OCI)indicates that the type of reproductive system of CH flowers is outcrossing,and pollinated;cleistogamy flowers are strictly cleistogamy.CL flowers belong to strict closed flower fertilization,without pollination media.(3)The fruit of Viola philippica is a capsule,which contains multiple seeds,and the fruit splits into three after ripening.In May,the fruit of CH flowers ripened and the seeds began to disperse;From June to October,CL flowers continued to bear and disperse seeds,and the number of seeds per plant of cleistogamy flower is significantly larger than that of chasmogamy flower.(4)There was no difference in shape and color between CH seeds and Cl seeds,but the length,width,and weight of CL seeds were significantly lower.(5)The germination characteristics of two kinds of seeds are different.Seeds from the two types of flowers began to germinate after 48 h of water absorption in greenhouse;however,initial germination was delayed by decreasing temperatures.At 10℃/20℃,both types of seeds began to germinate on the 6th day,and the time needed for the germination rate of CL seeds to reach 50%is shorter than that of CH seeds.The optimal germination temperature for the two types of seeds was 20℃/30℃,which triggered a germination rate above 95%.On the other hand,at 10℃/20℃ day/nigh,the germination rate and vitality index of CL seeds were significantly higher than those of CH seeds.4)The germination rate of CH seeds in a low-concentration NaCl solution(0.05-0.1 mol·L-1)was lower than in a control solution(distilled water),while the germination rate of CL seeds was higher.However,the germination rate of the two types of seeds was lower after recovery by rehydration..After rehydration,the germination rate of the two types of seeds is lower.