Abstract Intensive vegetable production in soil is commonly associated with low N use efficiency (NUE) and consequently appreciable N losses that have negative environmental impacts. Improved N management practices for intensive vegetable crops require detailed knowledge of crop response to N supply. This study evaluated the effects of increasing total available N (TAN, i.e. the sum of soil mineral N at planting, N mineralized from organic matter, and mineral fertilizer N applied by fertigation) on cucumber grown in soil in a greenhouse. Parameters assessed were: yield, dry matter production (DMP), crop N uptake, nitrogen use efficiency (NUE) and potential NO3− leaching loss. The study was conducted in three growing seasons, in autumn, spring and late spring. Three commercial cultivars were examined, in the Late Spring crop, to assess possible cultivar differences. Five N treatments were applied, in the Autumn and Spring crops, as different N concentrations in nutrient solution that were applied in all irrigations throughout the crops. The applied N concentrations were N1: 0.7–1.0 mmol L-1, N2: 4.7–5.7 mmol L-1, N3: 12.1–13.8 mmol L-1, N4: 16.3–17.6 mmol L-1 and N5: 19.7–21.1 mmol L-1. The cultivar ´Strategos´ was used in both crops. Three N treatments (N1: 2.4 mmol L-1; N2: 8.5 mmol L-1and N3: 14.8 mmol L-1) were continuously applied throughout the Late Spring crop to three different cultivars (´Strategos´, ´Padrera´, and ´Mitre´). Total and marketable yield, relative to maximum value, and DMP were strongly related to TAN in linear-plateau relationships for the three growing seasons and three cultivars. Using relationships that include data from the three cropping seasons and the three cultivars, TAN values for maximum DMP, total yield, and marketable yield were 222 ± 15 kg ha−1, 221 ± 14 kg ha−1 and 228 ± 15 kg ha−1, respectively, for the Autumn, Spring and Late Spring crops. The relationships of crop N uptake to TAN, and DMP to crop N uptake, were described by a logarithmic equation. The relationship of N uptake efficiency to TAN (i.e. N uptake/TAN) was described by an exponential decay equation. Considering all crops and cultivars, these relationships were described by individual equations with R2 values of 0.75-0.96. The consistency of these relationships indicate that there are general responses of greenhouse-grown cucumber to N, which is not affected by growing season or cultivar. Measured NO3− leaching losses were low because of good irrigation management. Residual mineral N was considered to be indicative of the potential NO3− leaching loss; residual soil mineral N increased exponentially with TAN, being 196 and 330 kg N ha−1 for the highest N treatments in the Autumn and Spring crops, respectively. The information provided by this study will enable the total N supply (TAN) to be matched to cucumber crop N requirements thereby reducing excessive N supply and consequent negative environmental impacts.

中文翻译：

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硝酸盐脆弱区温室土壤黄瓜作物对总有效氮的响应

摘要 土壤中的集约化蔬菜生产通常与低氮利用效率 (NUE) 相关，因此会造成显着的氮损​​失，从而对环境产生负面影响。改善集约化蔬菜作物的氮管理实践需要详细了解作物对氮供应的反应。本研究评估了增加总有效氮（TAN，即种植时土壤矿物氮、有机质矿化氮和通过灌溉施肥施用的矿物肥料氮的总和）对温室土壤中生长的黄瓜的影响。评估的参数包括：产量、干物质产量 (DMP)、作物氮吸收、氮利用效率 (NUE) 和潜在的 NO3− 浸出损失。该研究在秋季、春季和晚春这三个生长季节进行。检查了三个商业栽培品种，在晚春作物中，评估可能的品种差异。在秋季和春季作物中应用了五种 N 处理，作为营养液中的不同 N 浓度，在整个作物的所有灌溉中施用。施用的 N 浓度为 N1：0.7-1.0 mmol L-1，N2：4.7-5.7 mmol L-1，N3：12.1-13.8 mmol L-1，N4：16.3-17.6 mmol L-1 和 N5：19.7-21.1毫摩尔 L-1。栽培品种“Strategos”用于两种作物。三种氮处理（N1：2.4 mmol L-1；N2：8.5 mmol L-1 和 N3：14.8 mmol L-1）在整个晚春作物中连续施用于三种不同的栽培品种（‘Strategos’、‘Padrera’和‘米特尔'）。在三个生长季节和三个品种中，相对于最大值的总产量和可销售产量以及 DMP 与 TAN 呈线性-高原关系。使用包括来自三个作物季节和三个品种的数据的关系，最大 DMP、总产量和可销售产量的 TAN 值为 222 ± 15 kg ha-1、221 ± 14 kg ha-1 和 228 ± 15 kg ha- 1、分别用于秋季、春季和晚春作物。作物 N 吸收与 TAN 和 DMP 与作物 N 吸收的关系由对数方程描述。N吸收效率与TAN的关系（即N吸收/TAN）由指数衰减方程描述。考虑到所有作物和栽培品种，这些关系由各个方程描述，R2 值为 0.75-0.96。这些关系的一致性表明，温室种植的黄瓜对 N 有普遍的反应，不受生长季节或品种的影响。由于良好的灌溉管理，测得的 NO3− 浸出损失很低。残留矿物 N 被认为是潜在的 NO3− 浸出损失的指标；残余土壤矿物质 N 随 TAN 呈指数增加，秋季和春季作物的最高 N 处理分别为 196 和 330 kg N ha-1。本研究提供的信息将使总氮供应 (TAN) 与黄瓜作物的氮需求相匹配，从而减少过多的氮供应和随之而来的负面环境影响。