Modeling plant nitrogen uptake and grain nitrogen accumulation in wheat.

摘要

Grain N concn. is a major quality parameter. In this study, a dynamic model was developed for simulating plant N uptake and grain N accumulation in wheat by focusing on the variation of N accumulation rate in individual grains. To support model development and evaluation, 5 experiments were conducted investigating effects of genotype, N fertilization rates and water regimes. In the model, rate of individual grain N accumulation was determined by N availability and interactions between factors such as temp., water and N conditions within plants over time. The availability of N in individual grains was the sum of N uptake and remobilization of N from the vegetative parts post-anthesis. Exponential relationships were found between post-anthesis N uptake and grain wt. as well as post-anthesis N uptake and N accumulation at the time of anthesis. It was assumed that N remobilization from the leaves decreased with leaf area index. N remobilization from the stems and chaffs (spikes without grains) was dependent on the wt. of stems and chaffs during grain filling and on the curvilinear or linear decreases in N concn. The model included 2 genotypic parameters: max. rate of individual grain N accumulation; and physiological filling duration of specific cultivars. Independent data sets from 3 field experiments (spanning 3 yr and comprising various genotypes, N and water levels) were used to validate the overall performance of the model. There was a good fit between the simulated and observed data. It is concluded that the model can provide a reliable prediction of grain N accumulation and protein formation in various wheat cultivars under different growing conditions.