底部渗灌下缓释肥对华北落叶松容器苗生长和氮积累的影响

Effect of sub-irrigation with slow-release fertilizer on growth and accumulation of nitrogen of Larix principis-rupprechtii Mayr container seedlings

【目的】确定底部渗灌技术下培育华北落叶松容器苗合理的缓释肥施用量,探索在高效节水的渗灌条件下缓释肥对华北落叶松容器苗的苗木生长以及氮养分积累的影响。【方法】以华北落叶松播种容器苗为研究对象,在底部渗灌条件下,采用单因素完全随机区组设计,设置3个不同浓度梯度的缓释肥施氮量(50、100、150mg/株),通过比较苗木不同生长期的形态指标、氮浓度和氮含量以及基质不同部位的酸碱度和电导率的差异,系统研究底部渗灌下缓释肥对1年生华北落叶松容器苗生长和氮积累的影响。【结果】施氮量对华北落叶松容器苗不同时期的苗高和地径影响差异显著。当施氮量为100 mg/株时,1年生华北落叶松容器苗的苗高、地径达到最大值,分别为34.38 cm、3.67 mm;施氮量对生长季末的根生物量影响差异显著,对茎、叶不同时期的生物量影响差异显著,当施氮量为100 mg/株时,华北落叶松容器苗的总生物量最大,生长季末达1.80 g;施氮量越大,华北落叶松容器苗各器官的氮浓度和氮含量越大,施氮量为150 mg/株下的氮浓度和氮含量显著高于50 mg/株的处理,而与100 mg/株的施氮处理无明显差异;当施氮量为150 mg/株时,苗木体内的氮浓度和含量达到最大,根、茎、叶的氮质量分数分别为1.78%、1.28%、2.14%,氮含量分别为8.41、9.56、11.71 mg/株,但其苗高、地径、生物量等形态指标呈下降趋势;随着施氮量的增大,基质的EC值升高、pH降低,且基质上层的EC值显著高于下层的,而pH则表现为上层较低,但未影响苗木质量。【结论】缓释肥能够促进华北落叶松容器苗生长,并且有利于苗木体内的氮积累;底部渗灌技术下培育华北落叶松容器苗合理的缓释氮量为100 mg/株。

[ Objective] Determining the appropriate slow-release fertilizer （SRF） application rate of Larix principis-rap- prechtii Mayr container seedling, and exploring the effect of fertilizer with sub-irrigation on seedling growth and nitrogen accumulation. [ Method] An univariate completely randomized block design with treatments of 50, I00,150 mg/ind （mg per individual） SRF was applied.Seedling morphological indexes, nitrogen concentration, media pH and electrical con- ductivity （EC） at different depth in different growth period were measured with different treatments. [ Result ] There were significant effects for plant height and root-collar diameter in different fertilizer application rates at different growth peri- od. The largest plant height （34.38em） and root-collar diameter （3.67 ram） were detected at 100 mg/ind SRF treat- ment. There was a significant effect on the root biomass at the end of the growing season, while the biomass of the stem and leaf was significantly different at different growth stages. The total seedling biomass was the highest（ 1.80 g） at the 100 mg/ind SRF treatment at the end of the growing season. The nitrogen concentration and nitrogen content in different organs increased with the increasing fertilizer application rate. N concentration and N content in 150 mg/ind SRF treat- ments were significantly higher than that of 50 mg/ind SRF, while no significant difference was observed between 100 mg/ind SRF and 150 mg/ind SRF treatments. The 150 mg/ind SRF treatment had the largest N concentration and con- tent, the nitrogen concentrations of root, stem and leaf were 1.78%, 1.28% and 2.14%, respectively, and the nitrogen contents were 8.41, 9.56, 11.71 mg/ind, respectively. However, the seedling morphological indexes including height, diameter and biomass declined. The EC value of the media increased and the pH value decreased with the increasing fer- tilizer application rate, and the EC value of the top media layer was higher than that of the bottom layer, while the pH value of the top layer was lower than the bottom, however, these did not affect the seedling quality. [ Conclusion ] SRF could promote the growth and nitrogen accumulation of L. principis-rupprechtii container seedlings. The optimum SRF a- mount is 100 mg/ind SRF per seedling under sub-irrigation.