The Biological Mechanism And Adaptive Significance Of Corispermum Lehmannianum Seeding In A Leaf-axil Area

Corispermum lehmannianum,,an early spring ephemeral plant,belongs to Chenopodiaceace,Corispermum and distributed in the Gurbantunggut Desert,which plays an important role in stability of sand.This study aimed to analyze the characteristics of adaptation in desert environment,and and explore the biological mechanism and adaptive significance by population statistics,reproductive ecology,laboratory experiments and field investigation in the Gurbantunggut Desert and different dune parts,seed setting characteristics,germination characteristics,dispersal ability and breeding system..The results showed:1.Population distribution characteristics: the important value(9.01%)of C.lehmannianum was lower than that of Haloxylon persicum(13.10%)in the Gurbantunggut Desert,which showed that C.lehmannianum had a significant ecological status.C.lehmannianum distributed on all dune slope,especially in the upper area of the sand dune.2.Fruiting characteristics and seed heteromorphism: the earliest leaf-axils seed was found in the lower part of shady slope and it's fruiting early than normal inflorescence seed in early life history.In the later stage of life history,the phenomenon of leaf-axils seed in the population was very common,but the number of leaf-axils seed was few.The leaf-axils seeds were accounted for the proportion of 2.02%,1.76% and 1.89% in smaller plants,medium plants and large plants,respectively.The size and weight of leaf-axils seed were smaller than the lower part of inflorescence,and were larger than the middle and upper part of inflorescence.3.Germination characteristics: the germination rate of leaf seed and normal born inflorescence was very low,and found that prolonging the storage time could not improve the seed germination rate.The seeds,which produced by this year and the last year,could not germinate.After pierce the seed coat,the seed germination rate has a substantial increase,among them,the seed germination rate of the leaf-axils was leaves was 98.89%,upper part of inflorescence was 52.22%,middle of inflorescence was 31.11%,lower part of inflorescence was 84.42%,respectively.4.Diffusion ability: the diffusion ability of leaf-axil seeds was weak,and the distance of diffusion was short At the wind speed of 4 m/s,the proportion of seed shedding from high to low was: upper part of inflorescence > middle of inflorescence > lower part of inflorescence > leaf-axils,many leaf-axil parts did not fall.Meanwhile,the spread distance from far to near was that: upper part of inflorescence > middle of inflorescence > lower part of inflorescence >leaf-axil.There was a significant negative correlation between seed propagation distance and seed weight.5.Pollen vitality and stigma can be granted: the pollen viability and stigma of C.lehmannianum were the strongest at 9: 30-10: 30,and with highest synchronism.The flowering period was during at May to June.Inflorescence flowers bloom from bottom to top gradually,this species also has a characteristics that was bloom and fructify at the same time.The top of the inflorescences was flowering period,the lower part of inflorescence had fruit.6.Mating system determination: the mating system of C.lehmannianum was facultative by pollination test,P / O ratio and OCI value..The P/O value was 1906 ± 510 and the OCI was 2.The self-fertility rate after bagging was 54.75%,which indicated that this species were self-friendly.The seed setting rate was 91.69% in the wild state,which had a significant difference between seed setting rate of wild rate and self-fertility rate(P <0.05).That might be due to there were more pollination opportunities from other plants in the wild state,which will greatly improve its seed setting rate.In conclusion,the mating system of C.lehmannianum was facultative,the germinate and diffusion were used to "cautious germination strategy" and "the nearest communication strategy",respectively.Although the proportion of leaf-axil seeds in plants was not high,but it common existed in the population.Besides,it played an important adaptive significance role in occupied habitat,reduce sibling rivalry and maintain the continuity.