AimsSymbiotic nitrogen fixation (SNF) contributes to improve grain yield under nitrogen (N) deficiency. Climbing beans are known to be superior to bush beans in their potential for SNF. The main objectives of this study were to: (i) quantify genotypic differences in SNF ability of climbing beans using 15N natural abundance method; (ii) identify climbing bean genotypes that combine high SNF ability with high yield potential that could serve as parents in the breeding program; and (iii) test whether δ15N in seed can be used instead of δ15N in shoot for estimating SNF ability.Methods98 Climbing bean genotypes were evaluated for SNF ability in terms of nitrogen derived from the atmosphere (%Ndfa). Field trials were conducted at two locations in Colombia.ResultsSignificant genotypic differences were observed in SNF ability. Good yielding lines with 4.6 t ha−1 fixed as much as 60% of their N (up to 92 kg of N fixed ha−1) without application of N fertilizer to soil.ConclusionsBased on evaluations from both locations, seven climbing bean lines (ENF 235, ENF 234, ENF 28, ENF 21, MAC 27, CGA 10 and PO07AT49) were identified as promising genotypes. Seed samples can be used to determine SNF ability, to select for genotypes with superior SNF ability.

中文翻译：

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攀缘豆共生固氮能力与种子产量的基因型差异

目的 共生固氮 (SNF) 有助于提高氮 (N) 缺乏下的谷物产量。众所周知，攀缘豆的 SNF 潜力优于灌木豆。本研究的主要目的是： (i) 使用 15N 自然丰度法量化攀缘豆 SNF 能力的基因型差异；(ii) 鉴定兼具高 SNF 能力和高产潜力的攀缘豆基因型，可作为育种计划中的亲本；(iii) 测试是否可以使用种子中的 δ15N 代替枝条中的 δ15N 来估计 SNF 能力。方法 98 根据来自大气的氮 (%Ndfa) 评估攀援豆基因型的 SNF 能力。在哥伦比亚的两个地点进行了田间试验。结果在 SNF 能力方面观察到显着的基因型差异。良好的屈服线与 4。6 t ha−1 固定了多达 60% 的 N（最多 92 kg 的 N 固定 ha−1），没有向土壤施氮肥。结论基于两个地点的评估，七个攀缘豆系 (ENF 235, ENF 234、ENF 28、ENF 21、MAC 27、CGA 10 和 PO07AT49）被鉴定为有前景的基因型。种子样本可用于确定 SNF 能力，选择具有优越 SNF 能力的基因型。