Field grown maize (Zea mays L. cv B73 × Mo17) plants, with and without ears, were sprayed with urea solutions to determine whether foliar application of N could prevent or delay the accelerated loss of reduced N from the leaf and leaf senescence induced by ear removal. Urea sprays were applied at 7, 14, and 21 days after anthesis in three separate and equal applications that provided a total of 67 kilograms N per hectare or 1 gram N per plant. Treatments were arranged in a 2 × 2 factorial in a randomized complete block with five replicates. Appropriate plant and leaf samplings and assays were made.In response to spray treatments, net increases of reduced N were detected in the whole shoot and plant parts, especially the stalk of the earless plants and grain of the eared plants. There was no effect of urea spray treatment on the normal loss of N from the leaves or rate of senescence of the eared plants or on the accelerated loss of N from the leaves or rate of senescence induced by ear removal. Grain and stover yields were unaffected by the spray treatment.Apparently the plants were unable to utilize the urea N applied to the vegetation (primarily leaves) after anthesis to enhance or extend the accumulation of dry weight by either eared or earless plants.
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机译：用尿素溶液喷洒有穗和无穗的田间玉米（Zea mays L. cv B73×Mo17）植株，以确定叶面施用N是否能够阻止或延迟由叶片诱导的叶片和叶片衰老引起的还原N的加速损失。摘耳。在花期后的第7、14和21天，分别分三次均匀施用尿素喷雾剂，每公顷提供总计67千克氮或每株植物1克氮。将治疗安排在2×2阶乘中，随机重复，重复5次。进行了适当的植物和叶片取样和测定。响应于喷雾处理，在整个芽和植物部分，特别是无耳植物的茎和有耳植物的谷粒中检测到了减少的N净增加。尿素喷雾处理对叶片中正常氮的损失或有穗植物的衰老速率没有影响，对叶片中氮的加速损失或除耳诱导的衰老速率没有影响。喷施处理不会影响谷物和秸秆的产量。显然，在开花后，植物无法利用施于植被（主要是叶子）的尿素氮来增加或延长有穗或无穗植物的干重积累。
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