氮素指数施肥对水杉一年生苗生长及氮素积累的影响

水杉(Metasequoia glyptostroboides)是我国特有的孑遗植物,优质种苗的培育是水杉造林成功的基础。通过探讨氮素指数施肥对水杉幼苗生长及氮素积累的影响,为水杉苗木培育提供基础。以一年生水杉幼苗为材料,采用温室盆栽方法,设定常规施肥(CF,纯氮用量5.0 g·株~(-1))和指数施肥(EF1、EF2、EF3、EF4,纯氮用量分别为1.0,3.0,5.0和8.0 g·株~(-1))。苗木生长结束后,测定水杉的地径、苗高、生物量及氮质量分数。结果表明,水杉的苗高、地径在不同施肥间没有显著差异,EF处理显著提高了水杉根、茎生物量的积累(P0.05),其中EF3处理的总生物量最高,为115.2 g·株~(-1);水杉茎、叶氮质量分数在不同施肥间的差异并不显著(P0.05);与CF相比,EF处理的根、茎氮积累量分别增加49.2%~84.4%,32.5%~34.9%,差异达显著水平(P0.05),其中EF3处理的氮积累总量为最大值,达2 938.9 mg·株~(-1)。施氮量为5.0 g·株~(-1)的指数施肥是水杉幼苗温室培育的适宜方法。

Growth and nutrient accumulation in seedlings of Metasequoia glyptostroboides with the N exponential fertilization

Metasequoia glyptostroboides is a China-specific relict plant species. Development of high quality seedlings of M. glyptostroboides plays important roles in forestation. To understand the effects of different nitrogenous exponential fertilization (EF) on seedling growth and nutrient accumulation, we conducted pot experiments in the greenhouse. The one-year-old seedlings were adopted and five treatment groups were designed including the conventional fertilization (CF) and exponential fertilization of EF1, EF2, EF3 and EF4 with the rates of nitrogen application being 5.0 g, 1.0 g, 3.0 g, 5.0 g and 8.0 g per seedling, respectively. We measured the height, ground diameter, biomass and nitrogen absorption after the seedling stop growing. We found that the seedling height and ground diameter showed no significant difference in different fertilizations. N exponential fertilization promoted the biomass of the root and stem (P<0.05). The total biomass achieved the maximum value of 115.2 g·plant^-1 under EF3 treatment. We also found that the nitrogen concentrations in the leaf and stem had no significant difference under different treatments. Compared with the CF, the nitrogen accumulation in the root and stem with EF treatments was increased by 49.2%-84.4% and 32.5%-34.9%, respectively (P<0.05), and the maximum nitrogen accumulation quantity was 2 938.9 mg·plant^-1 under EF3 treatment. The adoption of exponential nitrogen of 5.0 g·seedling^-1 was the best in cultivating M. glyptostroboides seedlings.