The photoassimilates and nitrogen (N) allocation in grain crops can be studied via the harvest index (HI) and the N harvest index (NHI). These two variables should be considered in breeding programs seeking more effective use of resources in maize ( L.) and other grain crops. Molecular biotechnology has emerged as a complement to improve not only maize grain yield but also resource utilization efficiency. A recent study reported a beneficial impact of increasing and extending the expression of a maize MADS-box transcription factor () on the NHI. This research aimed to further identify enhancements of C-N partitioning (HI, NHI) in DP202216 maize hybrids recognizing the main physiological and morphological traits associated to the C-N dynamics via in-season intra-canopy measurements. Two DP202216 elite hybrids were evaluated with their respective wild-type (WT) controls during two field growing seasons under two N regimes. The N nutrition index (NNI), as crop N status, was quantified to avoid misinterpretations of the results. The DP202216 trait showed, on average, a ∼6% increase in the HI with a concomitant positive impact of ∼9% in the NHI across hybrids, N regimes, and seasons. Those increases were consistent at different crop NNI. After accounting for the NNI, it was shown that the increases in both HI and NHI were supported by the accumulation of more N in leaves (mainly in both lower and middle sections of the canopy vertical profile) and more water-soluble carbohydrates (WSC) in stems before flowering, combined with more aggressive post-anthesis remobilization. In this study, it was shown an increase in the efficient use of crop resources in DP202216 hybrids with respect to their isogenic WT controls at similar NNI via increments in C and N partitioning (HI and NHI). This physiological and morphological understanding of C- and N-related traits addressed the challenge of optimizing the effective use of resources in maize breeding programs. To better understand traits by management interactions with yield and yield stability, DP202216 hybrid evaluations across a broad range of commercially relevant N scenarios would be valuable.

中文翻译：

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DP202216玉米杂交种碳氮分配优化

粮食作物中的光同化物和氮（N）分配可以通过收获指数（HI）和氮收获指数（NHI）来研究。在寻求更有效地利用玉米和其他粮食作物资源的育种计划中应考虑这两个变量。分子生物技术的出现不仅提高了玉米产量，而且提高了资源利用效率。最近的一项研究报告了增加和延长玉米 MADS-box 转录因子 () 的表达对 NHI 的有益影响。本研究旨在进一步确定 DP202216 玉米杂交种 CN 分配（HI、NHI）的增强，通过季节内冠层测量识别与 CN 动态相关的主要生理和形态特征。两个 DP202216 优良杂种在两个 N 制度下的两个田间生长季节期间与其各自的野生型 (WT) 对照进行了评估。氮营养指数 (NNI) 作为作物氮状况进行了量化，以避免对结果的误解。 DP202216 性状显示，平均而言，HI 增加约 6%，同时对杂交种、N 制度和季节的 NHI 产生约 9% 的积极影响。这些增加在不同作物 NNI 下是一致的。考虑 NNI 后，结果表明，HI 和 NHI 的增加是由叶片中更多氮的积累（主要在冠层垂直剖面的下部和中部）和更多水溶性碳水化合物（WSC）支持的。在开花前的茎中，结合更积极的花后再动员。在这项研究中，通过增加 C 和 N 分配（HI 和 NHI），DP202216 杂种相对于类似 NNI 的同基因 WT 对照，提高了作物资源的有效利用。这种对 C 和 N 相关性状的生理和形态学理解解决了在玉米育种计划中优化资源有效利用的挑战。为了通过管理与产量和产量稳定性的相互作用更好地了解性状，在广泛的商业相关氮情景中进行 DP202216 混合评估将很有价值。