Study On The Fruit Development Process And The Seed Suitable Harvest Period Of Viola Philippica

Viola philippica belongs to the perennial herb of the genus Viola in the Violaceae.In the same individual,two flowers with completely different shapes appear in different periods--chasmogamous(CH)and cleistogamous(CL)flowers.CH flowers bloom in early spring,are showy and purple in color,and are of high ornamental value.The petalless flowers of CL have a long green period and continue to bloom and bear fruit,making it an excellent landscaping plant.Due to the character of continuous bear fruit and continuous spreading seeds in the V.philippica.This will cause seed loss and make seed production difficult.This study V.philippica as the research object.The purpose of this experiment is to explore the development of V.philippica fruit process and different maturity seed germination characteristics.By comparing different pattern in different maturity seed morphology and vitality.To figure out the shape of the fruit and seed maturity and vigor.This result to determine the V.philippica fruit division standard,the determination of the optimal period for seed harvesting,and provide scientific basis for seed production.The main results are as follows:(1)The fruits of dimorphic flowers of V.philippica are capsules.CH the fruit is mature in the 23 to 28 days after flowering.CL the fruit is mature in the 11 to 26 days after flowering.The fruit dehided along the dorsal suture after ripening.The color and seed morphology of CH and CL fruits were consistent at different developmental stages.With the continuous improvement of fruit maturity,the included angle between fruit and stalk increases,from 0°to 90°,and then to 180°.The fruit changes color from light green to emerald green and finally to grayish white.According to the angle between the fruit and fruit stalk and the morphological characteristics of the fruit,the fruit(seed)according to the maturity is divided into eight periods.The angle between the fruit not upright and the petiole was 0°,the fruit was light green,and the seed was white or creamy was scored as period Ⅰ.The fruit set upright with an angle of 60°between it and the petiole,the emerald green color of the fruit,and the yellowish status of the seeds were scored as period II.The angle between the fruit and the petiole was greater than 60°but not vertical,and the condition in which the fruit was emerald green and the seed was yellow was scored as period Ⅲ.Vertical between the fruit and the petiole,the emerald green color of the fruit,and the brown yellow color of the seeds were scored as period IV.The angle between the fruit and the petiole was 120°when the fruit was not completely upright,the fruit was yellowish green,and the light brown color of the seeds was scored as period V.The angle between the fruit and the petiole was 150°,the fruit was yellowish green,and the brown color of the seeds was scored as period VI.The angle between the fruit upright but not dehisced and the petiole was180°,the fruit was grayish white,and the seed black was scored as period VII.The fruit was upright and just dehisced,the fruit was grayish white,and the seed had not yet ejected black and was scored as period VIII.In different stages of seed development,the trend of water content was opposite,that is,1000-seed weight increased and water content decreased.When the seed is fully mature(Ⅷ period)1000 seed weight reaches the maximum,at this time the water content is the lowest.The length,width and 1000-seed weight of CH seeds were larger than CL seeds.(2)The CH flowers of V.philippica begin fruiting from the end of April to the end of May,while the CL flowers begin fruiting from June to October.The seed setting rate and seed yield of CL flowers were significantly higher than those of CH flowers.There was no significant difference in the average ejection distance between CH and CL seeds.(3)The seeds of V.philippica with different maturity had the ability to germinate in three temperature cycles of 15℃/25℃,25℃ constant temperature and 25℃/35℃ except the Ⅰ period,and there were differences among germination behaviors.The germination percentage,germination index and vigor index of seeds at lower maturity(before Ⅳ period)were significantly lower than those after Ⅳ period.Under the three temperature treatments,the germination percentage of seeds in each month in the Ⅴ～Ⅷ stage was more than 80%,the germination index was more than 10,and the vigor index was more than 200.25/35℃was the most suitable temperature for the germination of V.philippica.Under this condition,the germination indexes were higher than other temperatures,and the germination rate,germination index and vigor index remained high after the stage Ⅳ.Considering many factors such as fruit color,shape,grain weight,germination index,vigor and so on,it is concluded that when the angle between fruit and fruit stalk is greater than 90°(after period Ⅳ)and the fruit color is gray,it can be used as the standard of fruit harvesting,which is full seeds,low water content,high germination rate,fast germination and strong seed vigor.