Abstract: 【Objective】 A consistent and useful system for virtual crop root system simulation was constructed with integrated hardware and software, and applied to quantify post-paddy wheat RSA. 【Method】 A crop RSA digitizer was designed and fabricated in a purely mechanical manner. The digitizer was constructed with a leveled rotating beam, a cross slider and a vertical slider. All the beam and sliders were calibrated with rulers. The coordinated movements of the three moving parts allows the measuring tip to access any possible point within the 3D root-soil volume. Root zone soil sample, installed on the platform of the digitizer, was stripped in layers, each in 3-5 mm thickness. The positions of the exposed roots were digitized. This laminated treatment continued until the whole RSA was digitized. Collected RSA data was then transferred to Pro-E, where the virtual RSA was reconstructed. As the data set used for RSA reconstruction came directly from undisturbed field-grown crop, the reconstructed virtual RSA was able to represent the actual RSA state and the dynamical process of RSA in situ. The virtual RSA was then analyzed with tools supplied in the Pro-E, where the 3D RSA parameters were calculated, such as soil exploration ability of root system, root total length and mean root elongation rate, etc. Wheat RSA dynamics was also quantified with these parameters. 【Result】 Being easy to operate, suitable for dusting environment and highly stable under noisy conditions, the proposed RSA digitizer provides a measurement resolution of <1 mm and can be used as a satisfactory tool for RSA measurement. Pro-E provides a means of realizing the virtual RSA, and also an in-depth computation of RSA parameters. Results shown that the proposed virtual RSA method was able to illustrate structural characteristics and soil exploitation abilities of root system in each stage of wheat seedling development, as well as the root-colonized soil depth and circumferential root expanding dynamics. High heterogeneity of RSA was observed in each wheat seedling stage. Wheat root was confined in shallow soil layers in winter, but rapidly expanded to deeper layers in standing and tillering stages. More rapid development of root was observed in the shooting stage. 【Conclusion】 The proposed virtual RSA, integrated with hardware and software, is a technical solution for accurate quantification of root system dynamics, root-soil relation, root topology and the dynamics of soil space exploration. This tool kit provides a solution for RSA quantification in each post-paddy wheat seedling stage, thus illustrating the dynamics of wheat RSAs and satisfying the practical needs for crop RSA study.

Key words: plant root architecture digitizer , virtual plant root tech , root system architecture , winter wheat