Alnus nepalensis seedling growth with N and P treatments

Key words: 
• botany /
• nitrogen and phosphorus /
• Alnus nepalensis /
• biomass

Abstract: Nitrogen（N） and phosphorus（P） are important nutrients for tree growth. There is low N and P content of mountain soil in Yunan Province. They maybe affect Alnus nepalensis seedling growth. This aim was to study Alnus nepalensis seedling growth with different N and P supply. Sand culture greenhouse experiments were used to determine the growth response of Alnus nepalensis to three N treatments （50，210，and 420 mg·L－1） and four P treatments（14，32，62，and 124 mg·L－1），of which the control treatment design was 210 mg·L－1 N and 62 mg·L－1 P. Split-plot design with 9 treatments and 5 replications was used in the experiment. Results showed：（1）There had significant changes in root biomass，shoot biomass，leaf biomass，height and diameter increments of seedlings with different N and P supply，but no interaction between N and P，of which the effect of N was remarkable（P ＜ 0.05），and P was extreme remarkable（P ＜ 0.01）. However，when N or P supply was less than the control，seedling growth reduced. （2）With increasing P and with N lower than 210 mg·L－1，the fine root mass/leaf mass ratio and root mass/shoot mass ratio was reduced，whereas with N of 210 mg·L－1 these two ratios increased.（3）Compared to the control，with N of 50 and 210 mg·L－1 as P increased，N content of roots and shoots decreased，but leaf N increased.（4）For all N treatments，P concentration in roots，shoots，and leaves was lowest with P 32 mg·L－1. In conclusion，there was an important effect of Alnus nepalensis seedling growth with balanced N and P supply or with increased P from a Hoagland solution.［Ch，4 fig. 3 tab. 9 ref.］