Abstract
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%.
