| Arisaema flavum(Forsk.)Schott belongs to the Araceae,which is mainly distributed in the south to southeast of Tibet,west of Sichuan and northwest of Yunnan.In Lhasa Valley,it is common in the habitat with an altitude of 2200 to 4400 meters,such as gravel slope,shrub,forest,wasteland,roadside and farmland.A.flavum is an important Tibetan medicine plant,its tuber is often used to reduce fever and treat cough,phlegm and asthma.In recent years,Tibetan medicine plants are one of the hot areas of botany research,especially the pharmacology and chemical composition of Tibetan medicine plants have made great progress,but there are few studies on the reproductive system and ecology of Tibetan medicine plants.In this paper,we systematically studied the flowering phenology,floral characteristics,pollen dispersal,breeding system,inflorescence warming and reproductive allocation of A.flavum distributed in Lhasa valley.The main results are summarized as follows:1.The results of florescence phenology study show that the florescence of a single plant A.flavum is about 11(11.38 ± 2.28)days,and that of a population is 28 days.2.The studies on the flower characteristics of A.flavum showed that in different habitats,there is no significant difference in floral characteristics except for the length of female inflorescence.It was also found that pistil degeneration existed in the flower structure of A. flavum.In the process of flowering of A.flavum,the activity of pollen decreased from 84 h after flowering,and the receptivity of stigma kept high from 84 h after flowering.The life span of pollen of A.flavum is 6 days after it leaves the plant,but it can't be increased under the conditions of 4 ? and dry storage.The pollen / ovule ratio(P/O)and the hybridization index(OCI)are 1678.72 and 3,respectively.These parameters indicated that A.flavum is self-compatible and heterozygous,and there is no apomixes in it,reflecting that A.flavum is a mixed mating system with self and cross.3.The study of pollen dispersal show that A.flavum is mainly pollinated by insects,not by wind.Flower visiting insects include flies,ants,bees,spiders,etc,among them,flies and ants are the main effective pollinators.There is no obvious law of pollen transmission of A.flavum,and pollinators randomly pollinate.4.There is a phenomenon of temperature rising after A.flavum flowering,and the highest temperature can be 18 ? when it rises.Comparing with the frequency of insect visiting flowers,it shows that the frequency of insect visiting flowers increases after the inflorescence temperature rises,and the time of the two is basically the same.5.The results of the research on the reproductive allocation of A.flavum show that:(1)there are no significant relationship between altitude and reproductive allocation in fruiting,and nutrient distribution of A.flavum(p>0.05),the results also show that there is no significant correlation between the above ground biomass and the reproductive allocation in fruiting in the three altitude bands of A.flavum(p>0.05).(2)There is no significant differences in the reproductive allocations in flowering and nutritional allocations of A.flavum in the three different habitats in the Lhasa area(P>0.05),namely,under the forest,in the rock cracks and the open land.However,there are significant decreasing trend of reproductive allocations in flowering of A.flavum with its aboveground biomasses in the habitats of open land and stone cracks(P<0.05),but there is no significant relationship between the aboveground biomasses and reproductive allocation in flowering in the habitat under the forest.(3)Furthermore,There is a significant difference for the reproductive allocation between flowering and fruiting stages of A.flavum(P<0.05). |
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