Petiole nitrate-nitrogen (NO₃–N) sampling and testing remains a popular in-season nitrogen (N) management practice in the western United States for cotton (Gossypium hirsutum L.). However, the present guidelines used by Arizona are greater than 35 yr old and are in need of updating. The objectives of this study were to relate in-season petiole NO₃ levels with lint yields and N deficiencies and to revise the former critical deficiency level guidelines by growth stage. Petioles were sampled between first square and peak bloom in nine site-years of cotton N management field trials in Maricopa and Safford, AZ, from 2014 to 2018. Irrigation type in Maricopa was overhead sprinkler irrigation (OSI) (2014–2015) and subsurface drip irrigation (SDI) (2016–2018). In Safford (2014–2017), surface irrigation (SI) was used. Petiole NO₃ in SDI was dramatically lower than with SI or OSI, mostly in the deficient range. Lower lint yields in zero-N treatments compared with pre-plant soil NO₃ test–based reference treatments occurred in eight site-years (Safford 2016 crop lost to late hailstorm) and were considered N deficient. Critical petiole NO₃–N levels from 1984 were revised downward 1 g N kg⁻¹ because several N-fertilized treatment means of petiole NO₃ were in that range and did not exhibit an N rate–related yield depression. Sampling cotton plants for petiole NO₃ analysis should start within 1 wk of first bloom. Petiole NO₃ dynamics and critical levels in SDI cotton required further study.

中文翻译：

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修订西南沙漠灌溉棉花叶柄硝酸盐充足/缺乏指南

叶柄硝酸盐氮 (NO ₃ –N) 采样和测试仍然是美国西部棉花 ( Gossypium hirsutum L. )流行的季节性氮 (N) 管理实践。但是，Arizona 使用的当前指南已超过 35 年，需要更新。本研究的目的是将季节性叶柄 NO ₃皮棉产量和氮缺乏水平，并按生长阶段修订以前的关键缺乏水平指南。从 2014 年到 2018 年，在亚利桑那州马里科帕和萨福德进行的 9 个场地年棉花氮管理田间试验中，在第一次盛开和高峰开花之间对叶柄进行了采样。马里科帕的灌溉类型是架空喷灌 (OSI) (2014-2015) 和地下滴灌（SDI）（2016-2018）。在 Safford（2014-2017 年），使用了地表灌溉 (SI)。SDI 中的叶柄 NO ₃显着低于 SI 或 OSI，主要在缺陷范围内。与种植前土壤 NO ₃测试为基础的参考处理相比，零氮处理的皮棉产量较低，发生在八个地点年（Safford 2016 作物因晚冰雹而损失），被认为是 N 缺乏。临界叶柄 NO1984 年的₃ –N 水平向下修正了 1 g N kg ^-1，因为叶柄 NO _{3 的}几种施氮处理方法在该范围内并且没有表现出与施氮率相关的产量下降。用于叶柄 NO ₃分析的棉花植株取样应在第一次开花后 1 周内开始。SDI 棉花叶柄 NO ₃动力学和临界水平需要进一步研究。