秸秆和氮肥不同配比影响平邑甜茶幼苗的生长和对氮素的吸收、分配和利用

为探讨秸秆和氮肥不同配比对平邑甜茶(Malus hupehensis)植株生长和氮素吸收、分配和利用的影响, 采用¹⁵N同位素示踪技术, 以二年生盆栽平邑甜茶为试材, 研究了不同秸秆和氮肥配比条件下平邑甜茶的生长、¹⁵N尿素吸收利用和土壤碳氮比等参数, 发现秸秆和氮肥不同配比对平邑甜茶植株的生长及¹⁵N-尿素的吸收、分配和利用具有不同的影响。园土和秸秆比在45:1的水平, 同时配施氮肥(N 300 mg·kg^-1)时, 植株株高、茎粗和植株总干重的值最高, 分别为85.33 cm、8.05 mm和74.68 g; 植株的全氮、¹⁵N吸收量和利用率也最大, 分别为0.938 g、0.029 g和9.74%。不加秸秆而仅施加氮肥(N 200 mg·kg^-1)的对照(CK)的根冠比最大, 为1.54, 显著高于其他各种处理。各试验处理地上部分从肥料中吸收分配到的¹⁵N量对地上部分全氮量的贡献率(Ndff)均大于地下部分, 且CK各器官Ndff值最高, 地上部分和地下部分分别为7.94%和4.69%。除CK外, 各处理¹⁵N分配率均是地上部>地下部。秸秆的施用显著提高了土壤的有机质、全氮含量和土壤有机质C/N比。相关性分析结果表明, 土壤有机质C/N比与植株地下部分Ndff值有极显著负相关性(p < 0.01), 与植株整株Ndff值有显著负相关性(p < 0.05)。建议果园秸秆配施氮肥时, 控制秸秆施用量在45:1水平, 氮肥在200-300 mg·kg^-1之间较好。

Effects of different ratios of straw to N-fertilizer on growth of Malus hupehensis seedling and its absorption, distribution and utilization of nitrogen

Aims The study was to explore the effects of different ratios of straw to N-fertilizer on growth of Malus hupehensis seedlings and ¹⁵ N absorption, distribution and utilization in them.
Methods Using ¹⁵N trace technique, we measured growth parameters (plant height, basal stem diameter and dry weight) and ¹⁵N parameters (absorption, N derived from fertilizer, distribution and utilization) of two-year-old M. hupehensis seedlings and C/N ratio in soil organic matter under different straw-nitrogen fertilizer treatments.
Important findings Seedlings grew best under the condition of 45 : 1 of soil to straw and 300 mg·kg^–1 N addition, showing the greatest height, basal stem diameter and total dry weight: 85.33 cm, 8.05 mm and 74.68 g, respectively. Total nitrogen, the ¹⁵N uptake and ¹⁵N utilization were also greatest: 0.938 g, 29.2 mg and 9.7%, respectively. The root/shoot ratio of seedlings without addition of straw (the control treatment) was 1.54, higher than those of other treatments. The ¹⁵N derived from fertilizer (Ndff) values of the aboveground parts for all the treatments were higher than those of the belowground parts, and the control showed the highest Ndff values in both aboveground and belowground parts, which were 7.94% and 4.69%, respectively. The ¹⁵N distribution ratios of the aboveground parts were higher than those of belowground parts in all treatments except the control. Straw additions could obviously increase the contents of organic matter and total nitrogen in soil and increase C/N ratio of soil organic matter. The correlation analysis showed that the C/N ratio of soil organic matter was significantly negatively correlated with the Ndff value of the belowground parts, as well as in the whole plant. Our findings suggest that it is better to apply nitrogen at rates between 200 and 300 mg·kg^–1 when corn straw is added into orchard soil.