The relationships between dynamics and plasticity (ability of a hybrid to modulate its traits according to growing conditions) of agronomic and nutritional traits are unclear. Quantifying and characterizing these relationships can improve understanding of plant response mechanisms to growing conditions in short cropping periods at high latitudes. This study investigated the dynamics of key agronomic performance and forage quality traits and the importance of their mean values for expression of plasticity. Data were collected on eight sampling occasions during the cropping period in 2013 and 2014, using six phenologically different forage maize hybrids grown at three high-latitude locations. The dynamics of all traits studies were significantly affected by hybrid and environment (combination of location and year). Dry matter yield (DMY) and dry matter content (DM) were affected by interactions between hybrid, growing conditions on each sampling occasion, and overall growing conditions in the different environments. Neutral detergent fiber digestibility (NDFD), starch (STA) concentration, water-soluble carbohydrate (WSC) concentration, and organic matter digestibility (OMD) in the hybrids differed significantly over time across the environments. Early-maturing hybrids progressed faster in maturity based on DM content and had higher STA concentration, NDFD, and OMD at a given time than later-maturing hybrids. Similar DMY and higher NDFD and OMD in early-maturing compared with later-maturing hybrids, regardless of sampling occasion or environment, suggests that use of early-maturing hybrids is advantageous in the short cropping season at high latitudes. For most traits, plastic ability [plasticity of trait x/mean value of trait x, or ability to change expression of plasticity of a trait is based on the mean value of the trait] was dependent on the mean value of a trait and declined with increasing mean value. Plastic ability of DM, DMY and STA was higher at early developmental stages and decreased at later developmental stages, but the opposite was true for WSC and CP. Although the dynamics of trait development over time differed between the hybrids, the dynamics of plastic ability for four traits (DM, WSC, OMD, NDF) were similar in all hybrids. These maturity characteristics-based responses of the six hybrids in terms of trait dynamics and plastic ability, and the dependence of plastic ability on the dynamics of corresponding trait, can potentially be exploited in development of new variety/hybrid and prediction models for further improving the agronomic and nutritional value of forage maize crops at high latitudes.

农艺和营养性状的动力学和可塑性（杂交种根据生长条件调节其性状的能力）之间的关系尚不清楚。量化和表征这些关系可以提高对高纬度地区短种植期植物对生长条件的反应机制的理解。本研究调查了关键农艺性能和牧草品质性状的动态及其平均值对可塑性表达的重要性。在 2013 年和 2014 年的种植期间，使用在三个高纬度地区种植的六种物候不同的牧草玉米杂交种收集了 8 个采样时间的数据。所有性状研究的动态都受到杂交和环境（位置和年份的组合）的显着影响。干物质产量 (DMY) 和干物质含量 (DM) 受杂交种之间的相互作用、每个采样场合的生长条件以及不同环境中的整体生长条件的影响。杂种中的中性洗涤纤维消化率 (NDFD)、淀粉 (STA) 浓度、水溶性碳水化合物 (WSC) 浓度和有机物消化率 (OMD) 在不同环境中随时间显着不同。根据 DM 含量，早熟杂种的成熟进展更快，并且在给定时间比晚熟杂种具有更高的 STA 浓度、NDFD 和 OMD。与晚熟杂交种相比，早熟杂交种具有相似的 DMY 和更高的 NDFD 和 OMD，无论采样场合或环境如何，这表明在高纬度地区的短耕季节使用早熟杂交种是有利的。对于大多数性状，可塑性能力 [性状 x 的可塑性 / 性状 x 的平均值，或改变性状可塑性表达的能力基于性状的平均值] 取决于性状的平均值，并且随着性状的平均值下降增加平均值。DM、DMY和STA的可塑性能力在发育早期较高，在发育后期降低，而WSC和CP则相反。尽管杂种之间的性状发展动态随时间不同，但所有杂种中四种性状（DM、WSC、OMD、NDF）的可塑性能力动态相似。六个杂种在性状动态和可塑性能力方面的这些基于成熟特征的响应，以及可塑性能力对相应性状动态的依赖性，