Maize growth, organ development, and yield formation are highly controlled by the manner in which the plant captures, partition, and remobilizes biomass and phosphorus (P). Better understanding of biomass and P accumulation, partition, and remobilization processes will improve modeling of crop resource use. However, there is still a lack of detailed data to parameterize the modeling of these processes, particularly for modern maize cultivars. A two-year (2016 and 2017) field experiment with three P fertilization treatments (0 (P0), 75 (P75), and 300 (P300) kg P₂O₅ ha⁻¹) was conducted on a Fluvo-aquic soil (Quzhou, Hebei province, China) to collect data and quantify key processes for a representative modern maize cultivar (Zhengdan 958) widely grown in China. The proportions of biomass and P partitioned into various maize organs were unaffected by P application rate. Zhengdan 958 showed a much lower leaf-senescence rate than older cultivars, resulting in post-silking leaf photosynthesis being sufficient to meet grain biomass demand. In contrast, 50%–85% of leaf P and 15%–50% of stem P accumulated pre-silking were remobilized into grain, in spite of the large proportion of post-silking P uptake. Our results are consistent with the theory that plants use resources according to the priority order of re-allocation from senescence followed by assimilation and uptake, with the re-translocation of reserves last. The results also enabled us to estimate the threshold P concentrations of Zhengdan 958 for modeling crop P demand. The critical leaf P concentration for individual leaves was 0.25%–0.30%, with a corresponding specific leaf P (SLP) of 75–100 mg P m⁻². The structural P concentration for leaf was 0.01%, corresponding to an SLP of 3.8 mg P m⁻². The maximum P concentrations of leaves and stems were 0.33% and 0.29%. The residual P concentration for stems was 0.006%.

Accurate leaf area simulation is critical for the performance of crop growth models. Area of fully expanded individual leaves of maize hybrids released before 1995 (defined as old hybrids) has been simulated using a bell-shaped function (BSF) and the relationship between its parameters and total leaf number (TLNO). However, modern high-yielding maize hybrids show different canopy architectures. The function parameters calibrated for old hybrids will not accurately represent modern hybrids. In this study, we evaluated these functions using a dataset including old and modern hybrids that have been widely planted in China in recent years. Maximum individual leaf area (Y₀) and corresponding leaf position (X₀) were not predicted well by TLNO (R² = 0.56 and R² = 0.70) for modern hybrids. Using recalibrated shape parameters a and b with values of Y₀ and X₀ for modern hybrids, the BSF accurately predicted individual leaf area (R² = 0.95–0.99) and total leaf area of modern hybrids (R² = 0.98). The results show that the BSF is still a robust way to predict the fully expanded leaf area of maize when parameters a and b are modified and Y₀ and X₀ are fitted. Breeding programs have led to increases in TLNO of maize but have not altered Y₀ and X₀, reducing the correlation between Y₀, X₀, and TLNO. For modern hybrids, the values of Y₀ and X₀ are hybrid-specific. Modern hybrids tend to have less-negative values of parameter a and more-positive values of parameter b in the leaf profile. Growth conditions, such as plant density and environmental conditions, also affect the fully expanded leaf area but were not considered in the original published equations. Thus, further research is needed to accurately estimate values of Y₀ and X₀ of individual modern hybrids to improve simulation of maize leaf area in crop growth models.