| Viola monbeigii,a perennial herb of Viola?Violaceae?with a unique breeding system,forming chasmogamous?CH?flower in early spring and cleistogamous?CL?flower in summer which provide a good material to research the mixed-breeding system and reproductive adaptation of plant.This article chooses the wild Viola monbeigii in the northwest normal university campus as research material.We studied the flowering phenology,floral morphology,breeding system,pollination biology and analyzed the seed setting rates and the morphological characteristics and germination characteristics of two types of offspring seeds aiming to uncover the ecological adaptation of the reproductive characteristics of dimorphism flower hoping to provide material for better understand the reproductive strategy of plant that own mixed breeding system.Main results are as follows:?1?CH flowers bloom in the middle of March lasting for 22-29days.The florescence of every single CH flower is about 6.6±0.81 days,and CH flowers isolated from insects could prolong the florescence significantly indicating that CH flowers could prolong lifespan ensuring reproductive success of itself.CH flowers were bisexual,bilateral symmetry,white,with five stamens.During the CH florescence,the relative spatial location of stigma and anther remained unchanged indicating that pollinators are needed for CH flowers.CL flowers without petal come out at the beginning of April lasting to the end of October.CL flowers are amphiprotic whose two stamen tightly adjoin to the stigma of pistil behaving cleistogamous completely.?2?The pollen ovule ratio,hybrid index and artificial pollination experiment showed that CH flowers of Viola monbeigii behaved outcrossing and partial self-compatible.However the autonomous selfing was not exist and CH flower can produce seeds through outcrossing.But the seed sets of CH flowers under natural conditions was low and the seed sets under artificial supplementary pollination was significantly improved showing pollen-limitation in CH flowers.The pollen ovule ratio of CL flowers showed that the breeding system was cleistogamy in accordance with the morphology observation.?3?We identified major forging insects,there were apis cerana?chinese bee?,Tetralonia?Apidae?and megachile,coelioxys?Megachile?of Hymenoptera.In addition,there are some insects such as flies which belong to diptera and thrips which belong to physopoda.But the bees were the major visitors and effective pollinators.Thevisitingfrequenciesoffourkindsofbeeswere1.5±0.08time·plant-1·hour-1,0.8±0.04time·plant-1·hour-1,0.5±0.02time·plant-1·hour-1,0.4±0.05time·plant-1·hour-1,and daily activity routine was affected by the climate.?4?The individuals of Viola monbeigii produced CH flowers about 4.87±0.39per plant on average in a year,however the fruit production of CH flowers was only0.67±0.24,and the seed setting rate was 51.35±4.22%.However the number of CL flowers was 23.83±4.30 per plant on average in a year and the fruit and seed setting rates were 20.73±20.73,86.85±6.75%,respectively indicating that most seeds of Viola monbeigii were produced by CL flowers which provided reproductive assurance for Viola monbeigii.?5?There were no significant differences in the morphological and size of the two types of seeds,but the hundred-grain weight of CH seeds was significantly higher than CL seeds?P<0.05?.The highest germination rates of CH and CL seeds that freshly collected were 23.33%?5?/20??and 16%?5?/20??.The seeds stored at room temperature for 3,6,9,12 months and low temperature stratification for 1,2,4 months can effectively promote the germination of CH seeds and CL seeds indicating that the storage and low temperature stratification can effectively break the dormancy of CH seeds and CL seeds.In addition,CH seed germination rate was significantly higher than CL's under the same condition?P<0.05?,indicating that CH seeds own better seed quality,so CH flowers may have a high degree of fitness. |
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