施肥对普陀樟苗木生长及养分吸收利用的影响

为了解不同施肥水平对普陀樟Cinnamomum japonicum var.chenii苗木生长及养分吸收利用情况的影响,设置了3个水平的田间试验,即不施肥(ck),常规施肥(T50,50 g·m-2)和增量施肥(T100,100 g·m-2),于2012年6月至9月观测苗高和地径,定期采集分析土壤和植物样品。结果表明:普陀樟苗木的苗高、地径、根部和茎部生物量均随施肥量的增加而增加(P<0.05);而叶生物量和总生物量在6月时随施肥量增加而升高(P<0.05),到9月时则呈先升后降的趋势(P<0.05)。苗木体内养分质量分数和单株养分含量随施肥量的增加而增加(P<0.05),不同处理均以叶片养分质量分数最高;养分吸收及利用率随着施肥的增加而降低(P<0.05),T50和T100处理各元素的吸收利用效率均为氮>磷>钾。到试验结束时,T50处理土壤养分质量分数与试验开始时持平,T100处理钾积累,ck引起钾亏缺。从移栽成活来看,T50苗木体内养分积累,有利于移栽成活,保持土壤养分平衡;而T100养分浪费。综合判断,普陀樟苗木最适需养量应为50 g·m-2到100 g·m-2,且较接近50 g·m-2。

Responses of Cinnamomum japonicum var. chenii growth and nutrient uptake to fertilization

A field experiment was conducted on nursery land of Zhoushan Forestry Academy in 2012 to compare three fertilizer treatments: no fertilizer （ck），a normal rate with 50 g·m^-2 of 15-15-15 compound fertilizer （T50）， and twice the normal rate（T100），on growth, nutrient uptake and utilization of Cinnamomum japonicum var. chenii seedlings. Results showed that sapling growth of root and stem biomass as well as height and ground diameter significantly increased with increasing rate of fertilizer（P＜0.05）. Increasing the rate of fertilizer also significantly increased（P＜0.05）nutrient concentrations in leaves and nutrient uptake by the plants. By contrast, both nutrient use efficiency and fertilization efficiency decreased significantly （P＜0.05） with increasing fertilizer rate，being the same order in T50 and T100: N ＞P ＞K. By the end of the experiment，soil available nutrient levels of T50 remained similar to the initial ones；whereas，T100 caused K increased，and ck caused K depleted. For the survival rate, T50 resulted optimal nutrient status in the plants， which was best for transplanting, but T100 induced luxury nutrient supply. Therefore, the optimum fertilizer rate for C. japonicum var. chenii was 50－100 g·m^－2.［Ch，1 fig. 5 tab. 24 ref.］