Use efficiency and responsivity to nitrogen of common bean cultivars

ABSTRACT Common beans are the main source of protein in underdeveloped countries, and nitrogen (N) is one of the nutrients the most limits the productivity of this crop. This study, under field conditions, aimed to: a) determinate through efficiency indices how N is used by 16 cultivars of common beans; and b) classify these cultivars regarding use efficiency and responsivity to N application. The experimental design was in randomized blocks in split-plot scheme, with four replicates. Main plots consisted of 16 cultivars of common beans commercially classified as ‘Carioca type’. Subplots comprised two rates of N: 20 and 120 kg ha-1 applied as top-dressing. The evaluations were number of pods per plant and grains per pod, hundred-grain weight, shoots dry matter at full flowering, straw and grains dry matter at physiological maturity and grain yield. Based on the dry matter and its nutrient contents, the N accumulations were calculated in shoots and grains. The agronomic, physiological, agro-physiological, recovery and use efficiencies of N were calculated. Cultivar BRSMG Uai stands out by agronomic, physiological, recovery and use efficiencies of N. Genotypes BRSMG Uai, BRS FC402, IPR Campos Gerais, IPR Maracanã and TAA Bola Cheia are efficient and responsive to top-dressing N application.

摘要 普通菜豆（Common beans）是欠发达国家的主要蛋白质来源，而氮（N）是限制该作物生产力的关键营养元素之一。本研究在田间条件下开展，旨在实现两大目标：a）通过效率指标分析16个普通菜豆品种对氮素的利用情况；b）基于氮素利用效率与氮肥响应性对供试品种进行分类。本试验采用裂区随机区组设计，设置4次重复。主区为16个商业化归类为‘卡里奥卡型（Carioca type）’的普通菜豆品种；副区设置两个氮肥施用量：以追肥方式施加的20 kg·ha⁻¹与120 kg·ha⁻¹。测定指标包括单株荚数、每荚粒数、百粒重、盛花期地上部干物质量、生理成熟期秸秆与籽粒干物质量，以及籽粒产量。基于干物质量及其养分含量，计算地上部与籽粒的氮素累积量，并进一步计算氮肥的农艺效率、生理效率、农艺生理效率、回收效率与利用效率。分析结果显示，品种BRSMG Uai在氮肥的农艺、生理、回收与利用效率上表现优异。基因型BRSMG Uai、BRS FC402、IPR Campos Gerais、IPR Maracanã及TAA Bola Cheia兼具氮素利用效率与追肥响应性。