Studies On Breeding Characteristics And System Of Gentiana Straminea Maxim.

Gentiana straminea Maxim.is one species of Gentianaceae.It is one of the important medicinal resources which is commonly used more than 2000 years in China.the quantity and distribution of this species are quickly reduced in China. National Medicines Agency has been listed it as the endangered medicinal wildlife resources in 1987.However,the study relating to the reproductive characteristics and endangered mechanism of Gentiana straminea Maxim.has seldom been done.the research object is the Gentiana straminea Maxim.in the eastern region of the Qinghai-Tibet Plateau,through field observations and laboratory tests,we study the characteristics of its pollination and fruit,the situation of seed dormancy,and propagation characteristics in the natural conditions,as well as tissue culture.This research further defines the propagation characteristics of Gentiana straminea Maxim. and preliminary studies its endangered mechanism.It makes scientific and effective measures for restoration and expansion of this species and provides theoretical reference and scientific basis for protection of Gentiana straminea Maxim.which is an important tibet medicinal natural resources,the main conclusions on Gentiana straminea Maxim.as followed:1.Analysis of related datas show that at an altitude of lower than 2500m area,between 2500 and 3500m area,higher than 3500m area,the density of the population is about 7.5,12.0 and 7.0(plants/quadrat)respectively,But the correlation between species density and altitude is not obvious(P> 0.05);the ratio of variance(V)and mean(m)of the sample datas of three experimental plots are more than 1,that is,V/M>1,which illustrates that the wild species of Gentiana straminea Maxim.in three areas of different attitudes,its spatial distribution pattern tends to clumped pattern.2.Usually at the end of June or at the beginning of July,the Gentiana straminea Maxim.begins to show buds,after about 7 days,a significant period of basic bud showing is almost end.The earliest flowering period is in early July,the period is about 30 days.the top flower of the inflorescence is first open,and the rest flowers of the inflorescence is not open in a fixed sequence.The entire open time of inflorescence is approximate from 5 to 8 days.In addition,the flower of Gentiana straminea Maxim.has obvious characteristics of male first to blossom and the combination of ectopic flower.3.Under the natural conditions,its self-pollination is unlikely,sexual reproduction needs pollinators that are mainly flies,bees and ants category,but the types and quantities are few and efficient pollination is low.The rate of natural fruit setting and seeding are both low.The rate of producing fruit of each one is between 47.06%and 81.58%.The rate of average producing fruit is 68.65%.Seeding rate is between 73.4 and 106.5(seed number / fruit),average seeding rate is 89.2(seed number / fruit).4.Seeds have dormancy characteristics.The rate of seed germination in distilled water is relatively low with the maximum of 39%.And with different concentrations of NAA,IAA and GA on seeds,the results of the treatments are different.With a concentration of 500ppm GA and after 24h'immersion,the treatment is the best, which strikingly improves the rate of seed germination(P <0.01),reaching up to 91%; In addition,with the low temperature layer treatment can also improve their germination rate after 4 months(P <0.01),their germination rate can reach to 56.97%, also much higher than the 31.13%of the compared.5.Taking seedling leaves,petioles and roots as explants for tissue culture,it can get regeneration plants of Gentiana straminea Maxim.eventually.And the induction rate can reach 91.2%,87.4%and 45.8%respectively;The differentiation rate can reach 68.37%;The propagation coefficient can reach 3,even can rench 5;The rooting rate can reach 85%.Transplanting the little plants to the field and the survival rate is up to 95%.6.The distribution of natural species of Gentiana straminea Maxim.is narrow and the trend becomes to shrink gradually.Because it maintains breeding species mainly by sexual reproduction.But this process has been restricted by the types and quantity of the pollinator,a certain number of ovule fertilization can not be completed,resulting in abortion and low seed setting rate further.Seeds are small with dormancy characteristics.So the necessary conditions for natural germination(temperature,light, moisture,etc.) may inhibit seed germination or seedling successful settlement due to factors such as litter thickness.Large-scale fragments of suitable habitat,and fragmentation as well as the disappearance might be main external factors for endangered Gentiana straminea Maxim.. 7.The recommendations for the resource protection:firstly,we not only develop its product but also protect its resource.Secondly,nature reserves must be established to conserve wild germplasm resources.Thirdly,technical studies on introduction cultivation should be strengthened and GAP funding base and germplasm base should be established.Lastly,we must strengthen resource protection and advocate the legislative.