不同施肥量对降香黄檀苗木生长和叶片养分状况的影响

以半年生降香黄檀苗木为研究对象,利用普罗丹水溶性复合肥（N-P₂O₅-K₂O：20-20-20）,按照施肥量（按N用量计算）0、400、800、1200、1600 mg/株设置5个施肥量处理开展指数施肥盆栽试验,探讨施肥量对降香黄檀苗木生长以及叶片养分含量的影响,运用临界浓度法确定降香黄檀苗木的适宜施肥量,为规模化培育降香黄檀壮苗提供科学依据。结果表明：降香黄檀苗高、地径以及总生物量、地上部分生物量均随施肥量的增加呈现先升高后降低的变化趋势,在施肥量（按N用量计算）为1200 mg/株时达到最大值,其苗高、地径、总生物量和地上部分生物量依次为(64.31±6.84)cm、(6.34±0.68)mm、(14.49±1.69)g/株、(11.78±0.63)g/株,比对照显著提高50.70%、26.55%、52.69%、73.49%（P<0.05）;地下部分生物量变化规律不明显,处理间差异不显著（P>0.05）;根冠比则随施肥量的增加呈下降趋势,且均显著低于对照（P<0.05）。苗木叶片的氮（N）、钾（K）含量随施肥量的增加而增大,而磷（P）含量则趋于稳定;降香黄檀苗木叶片N、K含量以及N/P含量比的最适范围分别为26.53~41.16 g/kg、25.86~39.18 g/kg、13.79~21.42,据此推断出采用N、P、K复合肥,半年生降香黄檀苗木的适宜施肥量（按N用量计算）为800~1200 mg/株。

Growth and Foliar Nutrition of Dalbergia odorifera Seedlings under Exponential Fertilization

In order to study the effects of fertilization on the growth and foliar nutrition of Dalbergia odorifera seedlings,and then determine the optimal fertilizer amount of D.odorifera seedlings for large-scale cultivation and afforestation,five dosages(0,400,800,1200,1600 mg Nitrogen(N)per seeding)of Prod compound fertilizer(N-P₂O₅-K₂O:20-20-20)were applied on 6-month old D.odorifera seedlings through an exponential fertilization pot trail.The results showed that the height,ground diameter,total biomass and above-ground biomass of D.odorifera seedlings increased with the addition of fertilizer up to 1200 mg N per seedling,where the maximum values were achieved,with an average height of(64.31±6.84)cm,an average ground diameter of(6.34±0.68)mm,an average total biomass of(14.49±1.69)g and an average above-ground biomass of(11.78±0.63)g,which increased by 50.70%,26.55%,52.69%and 73.49%compared to the control treatment(P<0.05),respectively.After then the growth performance and biomass accumulation were inhibited slightly.No statistical differences(P>0.05)were observed on the below-ground biomass among different fertilizer supply.The ratio of root and shoot biomass decreased with the increase of fertilizer supply,while foliar content of N and potassium(K)increased.However,phosphorus(P)tended to be stable with the addition of fertilizer.According to the critical level approach,the optimum range of N,K content and N/P ratio for D.odorifera leaves was 26.53-41.16 g/kg,25.86-39.18 g/kg and 13.79-21.42,respectively.Based on these data,it could infer that when using N,P,K compound fertilizer,800-1200 mg N per seeding would be the optimal fertilizer amount for 6-month old D.odorifera seedlings.