The response to nitrogen (N) rate for two potato (Solanum tuberosum L.) cultivars grown in a sub-tropical climate was evaluated during two spring seasons. Early-maturing tablestock potato cultivars, ‘Fabula’ and ‘Red LaSoda’, were grown using surface-drip irrigation. N fertilizer was applied through irrigation drip tape at 0, 112, 224, and 336 kg ha⁻¹ of N. There was no difference of aboveground and tuber biomass accumulation between N fertilizer rates from 112 to 336 kg ha⁻¹ of N during both growing seasons. Seasonal differences were observed in N recovery efficiency; in Season 1, apparent N recovery (ANR) was significantly higher for N rates of 112 and 224 kg ha⁻¹ N for ‘Fabula’ and 112 kg ha⁻¹ of N for ‘Red LaSoda’, respectively. In Season 2, there was no significant difference between ANR values among N rates between 112 and 336 kg ha⁻¹ of N, for both cultivars. There was a significant interaction of N rate and growing season on total and marketable yields. In Season 1, average total and marketable yields for both cultivars increased from 9.8 Mg ha⁻¹ with no N applied, to 25.8 Mg ha⁻¹ with 224 kg ha⁻¹ of N; no significant differences were observed at higher N rates. In Season 2, high early season rainfall likely depleted available soil N, resulting in decreased N recovery efficiency of plants and significantly lower yield compared to the previous season. N-fertilizer rates above 224 kg ha⁻¹ of N did not increase total or marketable yields in both seasons. High rainfall events at the beginning of the Season 2 likely caused N stress and reduced tuber yields by 54% compared to the previous season. Results also highlighted the dominant effect of environmental conditions, particularly rainfall, on tuber yield and harvest quality response to N fertigation rate.

在两个春季期间，评估了在亚热带气候下种植的两个马铃薯（Solanum tuberosum L.）品种对氮（N）速率的响应。早熟的马铃薯马铃薯栽培种'Fabula'和'Red LaSoda'使用表面滴灌技术进行种植。通过灌溉滴灌带分别在0、112、224和336 kg ha ^-1的氮肥下施用氮肥。在两次施肥期间，从112到336 kg ha ^-1的氮肥施用量之间，地上和块茎生物量积累无差异生长季节。氮的回收效率存在季节性差异。在第1季中，表观氮的回收率（ANR）分别对于112和224 kg ha ^-1的 N比率显着更高，'Fabula'和112 kg ha ^-1N分别代表“ Red LaSoda”。在第2季中，两个品种的N量在112和336 kg ha ^-1之间的N量之间，ANR值之间没有显着差异。氮素含量和生长季节对总产量和可销售产量之间存在显着的相互作用。在第1季中，两个品种的平均总产量和可销售单价从不施氮的9.8 Mg ha ^-1增加到有224 kg ha ^-1的25.8 Mg ha ^-1。在较高的氮含量下，未观察到显着差异。在第2季中，早季的高降雨可能耗尽了可用的土壤N，与上一季相比，导致植物的N回收效率下降，单产大大降低。224 kg ha ^-1以上的氮肥施用量的氮肥在两个季节都没有增加总产量或可销售的产量。与前一个季节相比，第2季开始时的强降雨事件可能导致N胁迫，并使块茎产量降低了54％。结果还强调了环境条件（尤其是降雨）对块茎产量和氮肥施用量响应的收获质量的显著作用。