Red osier dogwood(Cornus sericea L.),widely distributed throughout North America,is essential for wildlife,thus biodiversity.It is recommended for reclamation or revegetation of sites disturbed by oil and gas extracti...Red osier dogwood(Cornus sericea L.),widely distributed throughout North America,is essential for wildlife,thus biodiversity.It is recommended for reclamation or revegetation of sites disturbed by oil and gas extraction because it tolerates a wide range of soil types and high pH levels.Since germination of this species is extremely difficult with long stratification requirements and poor germination,cuttings facilitate propagation.In this study,to develop techniques to propagate the species from stem cuttings,four concentrations of indole-3-butyric acid(IBA)and two cutting ages previous year’s growth(PYG)and current year’s growth(CYG)were investigated for survival and growth.After 4 months,survival rate,height growth,and shoot biomass from PYG cuttings were enhanced with IB A.In contrast,IB A did not affect these parameters in CYG cuttings.Root morphology was significantly affected by IB A concentration and cutting age.IBA,at higher concentrations,increased root surface and length.Total root surface area and length of PYG cuttings were increased,which may facilitate the absorption of essential resources and consequently increase growth.The results indicate that increasing the concentration of IB A may be an effective way to have better plant survival and growth of previous year’s cuttings in red osier dogwood.展开更多
The estimation of chronologic age based on the stages of third-molar development was evaluated by using the eight stages （A–H） method of Demirjian and the third-molar development was compared, in terms of sex and a...The estimation of chronologic age based on the stages of third-molar development was evaluated by using the eight stages （A–H） method of Demirjian and the third-molar development was compared, in terms of sex and age, with results of previous studies. The samples consisted of 291 orthopantomograms from young Chinese subjects of known chronologic age and sex （including 139 males with a mean age of 14.67±3.62 y and 152 females with a mean age of 14.85±3.70 y）. Statistical analysis was performed by employing the Mann-Whitney U-test and the t-test. Regression analysis was conducted to obtain regression formulas for calculating dental age from the chronologic age. Our results showed statistically significant differences （P〈0.05） in third-molar development between males and females, at the calcification stages D, E and H. And a strong correlation was found between age and third-molar development in both males （r2=0.65） and females （r2=0.61）. New equations （Age=8.76＋1.32 Development stage） for estimating chronologic age were derived. It is concluded that third-molar genesis took place earlier in males than in females. The use of third molars as a developmental marker is appropriate in young adults of Central China. The formula obtained in the present study can be used as a guide for estimation of dental maturity and a standard for age estimation for young adults of Central China.展开更多
基金supported by the Natural Sciences and Engineering Research Council of Canada(Innovation Enhancement Grants—NSERC CCIP 517845-17)。
文摘Red osier dogwood(Cornus sericea L.),widely distributed throughout North America,is essential for wildlife,thus biodiversity.It is recommended for reclamation or revegetation of sites disturbed by oil and gas extraction because it tolerates a wide range of soil types and high pH levels.Since germination of this species is extremely difficult with long stratification requirements and poor germination,cuttings facilitate propagation.In this study,to develop techniques to propagate the species from stem cuttings,four concentrations of indole-3-butyric acid(IBA)and two cutting ages previous year’s growth(PYG)and current year’s growth(CYG)were investigated for survival and growth.After 4 months,survival rate,height growth,and shoot biomass from PYG cuttings were enhanced with IB A.In contrast,IB A did not affect these parameters in CYG cuttings.Root morphology was significantly affected by IB A concentration and cutting age.IBA,at higher concentrations,increased root surface and length.Total root surface area and length of PYG cuttings were increased,which may facilitate the absorption of essential resources and consequently increase growth.The results indicate that increasing the concentration of IB A may be an effective way to have better plant survival and growth of previous year’s cuttings in red osier dogwood.
文摘The estimation of chronologic age based on the stages of third-molar development was evaluated by using the eight stages （A–H） method of Demirjian and the third-molar development was compared, in terms of sex and age, with results of previous studies. The samples consisted of 291 orthopantomograms from young Chinese subjects of known chronologic age and sex （including 139 males with a mean age of 14.67±3.62 y and 152 females with a mean age of 14.85±3.70 y）. Statistical analysis was performed by employing the Mann-Whitney U-test and the t-test. Regression analysis was conducted to obtain regression formulas for calculating dental age from the chronologic age. Our results showed statistically significant differences （P〈0.05） in third-molar development between males and females, at the calcification stages D, E and H. And a strong correlation was found between age and third-molar development in both males （r2=0.65） and females （r2=0.61）. New equations （Age=8.76＋1.32 Development stage） for estimating chronologic age were derived. It is concluded that third-molar genesis took place earlier in males than in females. The use of third molars as a developmental marker is appropriate in young adults of Central China. The formula obtained in the present study can be used as a guide for estimation of dental maturity and a standard for age estimation for young adults of Central China.
