Study On Pollination Ecology Of Ophiorrhiza Japonica In The Dolomite Karst Area,Shibing(Guizhou)

Ophiorrhiza japonica is a perennial herb of the Rubiaceae Ophiorrhiza genus.It has both pink and white flower color phenotypes and two long and short style types.It is used to study plant breeding systems and adaptive evolution characteristics good material.This paper takes O.japonica in karst area as the research object,and systematically studies its different flower color phenotypes and style types from the aspects of plant comprehensive characteristics,pollination biology,and breeding system,and compares different flower color phenotypes and flower parts between style types.Basic characteristics,flower-visiting insect species and behaviors,breeding system characteristics,and different artificial pollination treatments,reproduction success rates,etc.,in order to clarify the reproduction laws and adaptive evolution characteristics of different flower types and style O.japonica,for exploring karst areas the adaptive evolutionary mechanism of plants provides important evidence.The main results are as follows:(1)The flowering period of O.japonica populations is from the end of February to the end of March,and the main pollinators of different flower color phenotypes are bees.The visit frequency of bees to different flower color phenotypes was significantly different,and the pink phenotype was more preferred(P = 0.001).(2)The pink phenotype single flower pollen amount is7252.7±1827.7 grains,the pollen-ovule ratio(P/O)is 80.5 ± 12.9,the white phenotype single flower pollen amount is 8250.9 ± 1818.0 grains,and the pollen-ovule ratio(P/O)is 164.7 ± 0.2,all between 31.9 and396.0,facultative self-coating,and sometimes pollinators are needed.Both pink and white phenotypes have a out-crossing index of 3,facultative selfing,and sometimes pollinators are needed.(3)The number of seeds of the natural control for pink and white phenotypes was lower than other treatments,and the self-pollination treatment was significantly higher than that of the natural control.The inter-type outcrossing had a higher seed number.Therefore,the pink and white phenotypes had insufficient pollination under natural conditions.Highly self-compatible,it is a hybrid mating system with both selfing and outcrossing.The preference of pollinators and a highly self-compatible breeding system are the main factors maintaining the flower color polymorphism of Snakeroot in karst areas.(4)A circle of white pubescence in the long-morph corolla tube covers directly above the anthers.Long-morph and short-morph have obvious spatial separation of sex organs,typical dimorphic style plants.The main pollinators of different style types are bees.There was no significant difference in the visit frequency of bees among different column types(P = 0.530).(5)The pollen content of the long-morph single flower is7972.4±1664.0 grains,the pollen-ovule ratio(P/O)is 125.6 ± 9.8;the single flower pollen content of the short-morph is 7280.6 ± 2059.2 grains,and the pollen-ovule ratio(P/O)is 82.7 ± 1.8.The P/O values of the long-morph and the short-morph are both between 31.9 and 396.0.They are facultative self-coating and sometimes pollinators are needed.Both the long-morph and the short-morph have a out-crossing index of 4.Outcrossing is dominant,and some are self-compatible,and pollinators are needed.(6)The long-morph can maintain more than 70% of the pollen vitality from day 1 to the 5th day,and it drops to 15.43% on the 6th day.the short-morph maintains more than 70% of the pollen vitality from day1 to the 3rd day.It dropped to 40.80% on the 4th day,and only 5% or less remained on the 5th and 6th days.The pollen vitality of the long-morph is stronger than that of the short-morph.Three days before the flowers bloom,the stigma receptivity of the two style types are the strongest.(7)The number of seeds in the natural control treatment of the long-morph and the short-morph was significantly lower than that of the other treatments.There was no significant difference between the selfed treatment and the internal treatment,but both were significantly higher than the inter-type treatment.It shows that both the long and short style types have insufficient pollination under natural conditions,and have a high degree of self-compatibility for the same type of pollen,and are a mixed mating system dominated by selfing.(8)The pubescence structure in the long-morph corolla tube has a significant thermal insulation effect.In the thermal imaging for 5consecutive days,the temperature of the long-morph was significantly higher than the temperature of the long-morph with pubescence removed.The long-morph pollen has better water resistance than the short-morph.The pollen vitality of long-morph after 2h,3h,and 4h soaking in water were 91.74%,74.76%,16.34%,and the pollen vitality of short-morph pollen after soaking for 2h,3h,and 4h were 93.34%,25.60%,and 9.58%respectively.