Studies On Simulation Model Of Morphologial Development In Wheat Plant

Modeling morphological construction in wheat is of significant importance for realizing virtual and digital growth of wheat plant. Based on through time-course observations on morphological characteristics of above-ground organs in wheat under different nitrogen rates and cultivar types, dynamic development processes of different organs with GDD as main line were simulated , and the effectiveness of nitrogen status on organ growth was quantified. The results indicated that the present model had a good performance in predicting organ morphological growth on wheat plant, and thus lay a foundation for further constructing virtual wheat plant.With time-course observations on leaf morphological properties (leaf length and leaf shape) on main stems and tillers under different nitrogen rates and winter wheat cultivars in two growing seasons, the change patterns of leaf morphology with growth progress and environmental factors were characterized and a dynamic model was developed to simulate dynamic growth characters of different leaves on wheat plant. The final leaf length at different leaf positions accorded with bimodal (two peaks) curve, with marked differences under different nitrogen rates. The growth dynamics of leaf length could be described with a logistic model (sigmoid curve), and the growth dynamics of leaf shape described with power function and quadratic equation. The effect of nitrogen status on leaf growth was quantified by the value of leaf nitrogen content. The model was validated with the field experiment data of different winter wheat cultivars. The average RMSEs of final leaf length, time-course leaf length and width on main stem were 8.4%, 12.3% and 8.9%, respectively, and the average RMSEs of final leaf length, time-course leaf length and width on tillers were 11.5%, 11.2% and 9.4%, respectively.Based on observations on leaf curvature characteristics on main stems and tillers under different nitrogen rates in Yangmai 9, a dynamic leaf curvature equation was deduced through force analysis on a wheat leaf and the equation was solved with parameterization. Simulation analyses were conducted on the equation with the experiment data and the results showed that the leaf curvature equation could reasonably and reliably describe the change pattern of leaf shape characteristics of wheat under different conditions.Based on time-course observations on leaf SPAD on main stem and tillers under different nitrogen rates and cultivar types in two growing seasons, the change patterns of leaf SPAD with growth progress and environmental factors were characterized, and the relationship between leaf SPAD and RGB was analyzed. A SPAD-based leaf color model was developed to simulate time-course growth characters of leaf SPAD on wheat plant. The results showed that the leaf SPAD at different leaf positions accorded with quadratic equation in growth initial stage and growth senescence stage, and kept a steady value in growth function stage, which showed remarkable differences under different nitrogen rates. The growth dynamics of leaf SPAD could be described with a subsection function, and the relationship between SPAD and RGB described with linear equation. The effect of nitrogen status on leaf SPAD was quantified by the value of leaf nitrogen content. The model was validated with the independent field experiment data of different winter wheat cultivars. The average RMSEs of time-course leaf SPAD on stem and tiller were 11.60% and 9.03%, respectively.Based on time-course observations on morphological properties (length, thickness and angle) of leaf sheath and stem on main stems and tillers under different nitrogen rates and cultivar types in two growing seasons, the change patterns of leaf sheath and stem with growth progress and environmental factors were characterized, and a dynamic model was developed to simulate dynamic growth characters of leaf sheath and stem on wheat plant. The results showed that the leaf sheath length at different tiller positions followed logarithm equation before jointing and sigmoid curve after jointing. The internode length and thickness could be described with sigmoid curve. The angle between leaf and stem fit with linear equation at initial growth stage and senescence stage, and was stable at functional growth stage. The effects of nitrogen status on leaf sheath and stem growth were quantified through the value of leaf nitrogen content. The model was validated with the field experiment data of different winter wheat cultivars. The average RMSEs of leaf sheath length, internode length, internode thick and angle between leaf and stem were 8.2%, 10.4%, 11.2% and 13.2%, respectively.Based on time-course observations on spike morphological properties (spike length, spike width and spike thickness) on main stems and tillers under different nitrogen rates and winter wheat cultivars in two growing seasons, the change patterns of spike morphology with growth progress and environmental factors were characterized and a dynamic model was developed to simulate growth characters of spike on wheat plant. The results showed that the final spike length at different tiller positions accorded with quadratic equation, which showed marked differences under different nitrogen rates. The growth dynamics of spike length could be described with a logistic model (sigmoid curve), and the growth dynamics of spike shape described with quadratic equation and linear equation. The effect of nitrogen status on spike growth was quantified by the value of 1 leaf nitrogen content. The model was validated with the field experiment data of different winter wheat cultivars. The average RMSEs of time-course spike length, width and thickness were 4.3%, 8.5% and 8.4%, respectively.Based on time-course observations on canopy morphological properties under different nitrogen rates and wheat cultivars in two growing seasons, a dynamic model was developed to simulate time-course growth characters of canopy topological structure on wheat plant. The results showed that the canopy topological structure accorded with sigmoid curve, with marked differences under different nitrogen rates. The growth dynamics of organ elongation could be described with a logistic model, and based on the relationship of organ elongation and PHYLL a dynamic structural model of wheat plant was developed. The model was validated with the field experiment data of different winter wheat cultivars. The average RMSEs of time-course canopy structure were 10.2%. The overall results indicated that the present model had a good performance in predicting canopy topological structure on wheat plant.