Simulation Models On Nitrogen Nutrient And Grain Quality After Anthesis In Barley

Four barley cultivars, named Yangnongpi 5, Yangsimai 3, Yangnongpi 2, Gangpi, were used to study N fertilization on nitrogen uptake and translocation and grain quality after anthesis under field condition. The models were constructed systematically to provide correlative references for barley cultivation. The main findings are as follow:Some assumptions were made during the nitrogen absorbability and translocation in barley as following: (1) After anthesis, the absorbed nitrogen from the soil was totally used for the grain protein formation. (2) After anthesis, the nitrogen stored in leaf, stem and spike starts to remobilize to the grain. Based on these assumptions, the dynamic models of nitrogen absorbability and translocation were constructed by relationship between dry matter accumulation and the nitrogen accumulation. In the model, the relationship between leaf nitrogen remobilization and the leaf area index were described with exponential functions. The nitrogen translocation from stem and spike showed nonlinear relations with the respective nitrogen contents in these two organs. The nitrogen accumulation in grain was closely related to grain dry matter weight and was expressed with exponential functions. The experiments showed that the absolute prediction error ranges of leaf nitrogen accumulation were 0.005~1.934 g·m-2 and the RMSEs were 0.555~0.814 g·m-2. The absolute prediction error ranges of grain nitrogen accumulation were 0.007~4.668 g·m-2,RMSEs were 0.188~2.548 g·m-2. The absolute prediction error ranges of stem nitrogen accumulation were 0.003~1.790 g·m-2, and the RMSEs were 0.658~0.990 g·m-2. The absolute prediction error ranges of spike nitrogen accumulation were 0.011~1.008g·m-2 and the RMSEs were 0.320~0.583 g·m-2. The models reflected an enhanced level of prediction and mechanism.This research supposed that during the barley grain filling, the grain nitrogen accumulation had the maximized tendency and the nitrogen demand of grain was supplied from the vegetative organs and the soil. Nitrogen absorbed from the soil was used completely for the grain. When nitrogen supply was insufficient, the grain would gain more nitrogen from the vegetative organ. Based on physiological development time,the model to predict 1000- grain weight was constructed. The absolute prediction error ranges for 1000-grain weight were 0.05～4.711g, and the RMSEs were 1.862g.