基于15N同位素技术的白菜水氮耦合效应研究

Water-nitrogen coupling effects of greenhouse Chinese cabbage based on 15N tracing technology

为研究水分调控对设施栽培下白菜肥料氮素利用的影响,采用15N稳定性同位素示踪技术,设计不同施氮量(115 kg/hm^2和230 kg/hm^2)及不同土壤水分控制下限(分别占田间持水量60%、70%和80%),分析不同水氮处理下白菜各器官生物量累积、氮素利用及其与影响因子之间的互动响应关系。结果表明,水分调控和氮肥施用存在协作效应,该协作效应在根系生物量上的作用尤为明显;同时,在230 kg/hm^2施氮量处理下,水氮协作效应对叶生物量累积影响显著;115 kg/hm^2施氮量条件下,白菜氮肥利用效率明显高于相同水分控制条件下230 kg/hm^2施氮量处理;115 kg/hm^2和230 kg/hm^2施氮量均以70%水分控制下限氮肥利用效率最高,分别达到60.1%和49.9%;氮肥利用效率与15N投入量呈极显著负相关(r=-0.988),与根系生物量呈极显著正相关(r=0.948)。实际生产中,推荐以70%土壤水分控制下限作为白菜高效利用氮肥(尿素)的水分控制指标。

In order to investigate the effect of water regulation on nitrogen utilization in greenhouse Chinese cabbage,15N stable isotope tracer technique was used and different nitrogen application rates(115 kg/hm^2 and 230 kg/hm^2) and different lower water control limits(60%, 70% and 80% of field water holding capacity,respectively) were designed. Biomass accumulation, nitrogen accumulation in different organs of Chinese cabbage under different water and nitrogen treatments were observed. The relationship between nitrogen utilization and its influencing factors was analyzed. The results showed that there was a synergistic effect between water regulation and nitrogen application, especially in root biomass. At the same time, under 230 kg/hm^2 nitrogen application rate, the synergistic effect of water and nitrogen on leaf biomass accumulation was significant. Under 115 kg/hm^2 nitrogen application, nitrogen use efficiency of Chinese cabbage was significantly higher than the same water control condition with 230 kg/hm^2 N application rate treatment;115 kg/hm^2 and 230 kg/hm^2 N application rate with 70% water control lower limit were the highest in nitrogen use efficiency, which reached 60.1% and 49.9%, respectively;Nitrogen use efficiency was negatively correlated with15N input amount(r=-0.988), and was positively correlated with root biomass(r=0.948).In practice, the lower limit of 70% is recommended as the water control index for high-efficient use of nitrogen fertilizer(urea) by Chinese cabbage.