Quantitative Evaluation Of Influence Of PROSTRATE GROWTH1Gene And Latitude Factor On Rice(Oryza Sativa) Canopy Structure And Light Distribution Based On Three-dimensional Structure Model

The discovery and separation of PROSTRATE GROWTH1(PROG1) gene made great contribution to reveal the molecular mechanism of rice evolution and study the molecular basis of rice plant architecture. PROG1gene controls prostrate growth habit of common wild rice. In the evolutionary process, mutation of PROG1disrupts the gene function and inactivates the gene expression, leading to the transition of growth habit from prostrate to erect. Therefore the gene plays an important role in improving rice architecture. But the influence of PROG1gene under different latitude environment on rice canopy structure characteristics is not quantitatively evaluated, especially when canopy is full covered.Two rice varieties were selected to plant in Beijing and Hainan in this study, Indica Teqing (TQ) and YIL18which was developed from TQ introduced into PROG1gene which controls tiller angle. Three-dimensional digital technology was used to reconstruct the three dimensional canopies of two contrasting rice varieties in three main growth stages, i.e. booting stage, heading stage and grain filling stage. The effects of PROG1gene and latitude factor on canopy structure characteristics were quantitatively evaluated using the virtual layer cutting method. Meanwhile the Monte Carlo ray tracing algorithm and Binary Spatial Tree structure were used to calculate solar direct radiation and the diffuse radiation in canopy was simulated by Turtle model in rice canopy to access the influence of PROG1gene and latitude factor on canopy light distribution in canopy.1、The three-dimensional coordinates of TQ and YIL18canopy were collected in situ in filed using the electromagnetic three-dimensional digitizer, and the topological and geometry information were measured at the same time. The three dimensional canopies of TQ and YIL18at three main growth stages were reconstructed based on the data. Virtual layer cutting method was used to evaluate rice canopy structure characteristics including spatial distribution of the mean leaf inclination angle, leaf inclination density and leaf area density.2、Comparing with canopy structure characteristics of TQ and YIL18at three growth stages, the results showed that YIL18had the prostrate growth tendency with lower height of canopy, more tiller numbers, narrower leaves and less leaf area index under the influence of PROG1gene. The tiller angles of YIL18reduced by19.0%,10.5%and7.4%than that of TQ at three growth stages, respectively, and the mean leaf inclination angle also decreased by33.1%,14.3%and10.1%. Meanwhile, leaf inclination angle range for YIL18, which accounted for the maximum proportion at the upper parts of canopy, was one grade (10°) lower than that of TQ. Furthermore, the spike grain number and thousand seed weight of YIL18were also significantly less than that of TQ (P<0.05).3%Comparing with canopy structure characteristics of TQ and YIL18between Beijing and Hainan, the rice canopy structure had significant differences between Beijing and Hainan. The results showed that the tiller angles of YIL18in Hainan reduced by24.5%,12.4%and10.0%than that in Beijing at three growth stages, respectively, and the mean leaf inclination angle also decreased by17.6%,28.2%and35.6%. Meanwhile the tiller angles of TQ in Hainan reduced by2.2%、7.2%and4.3%respectively and the mean leaf inclination angles decreased by5.4%、22.2%、 15.1%than that in Beijing. The leaf inclination angle range for rice canopy in Hainan, which accounted for the maximum proportion at the upper parts of canopy, was one grade (20°) lower than that in Beijing. The rice canopy in low latitude district had lower tiller angle and leaf inclination angle than that in high latitude district.4、Comparing with contribution rate of PROG1gene and latitude factor on tiller angle and leaf inclination angle of rice canopy, the results showed that contribution rate of PROG1gene and latitude factor on tiller angle were approximate, about50%, however contribution rate of latitude factor on leaf inclination angle of rice canopy was significant higher than that of PROG1gene. Rice canopy can adjust angles of organs to adapt the change of solar elevation.5、Monte Carlo ray tracing algorithm and Binary Spatial Tree structure was used to calculate solar direct radiation and the diffuse radiation in canopy was simulated by Turtle model to access the light distribution in rice canopy.6%The effects of PROG1gene on light distribution in rice canopy was quantitatively evaluated. The results showed that there had significant difference in vertical distribution of solar direct radiation and diffuse radiation in canopy between TQ and YIL18. The light interception rate in canopy of TQ was0.28、0.29and0.23at three stages respectively. The light interception ratio was higher in middle canopy of YIL18(0.30、0.26and0.19at three stages respectively) and the upper parts of canopy had high light transmittance. The total photosynthetically active radiation in middle and upper parts of canopy of YIL18was significantly less than that of TQ. The canopy structure of YIL18was not beneficial to improve light interception.7-. The influence of latitude factor on light distribution in rice canopy was quantitatively evaluated The results showed that relative intensity of total photosynthetically active radiation in rice canopy in Beijing were higher than that in Hainan when solar elevation was40°. Oppositely, when solar elevation was80°the relative intensity of total photosynthetically active radiation in middle and upper parts of rice canopy in Hainan were more than that in Beijing. The rice canopy with higher tiller and leaf inclination angle can obtain more photosynthetically active radiation in high latitude district and that with low tiller and leaf inclination angle was beneficial to get photosynthetically active radiation in low latitude district. The change of tiller and leaf angles in different latitude districts was mainly related to the change of solar elevation what revealed the evolution law of rice canopy in different latitude environment.The assessment results of PROG1gene and environmental effects on canopy structure of rice reveals evolution regularity of rice architecture under the influence of PROG1gene and latitude factor. Meanwhile the results can also be applied to establish the relationship between PROG1gene, environmental factors and structural parameters and combine PROG1gene and crop physiological and ecological models to predict yield response under different gene and environmental effects for further breeding programs.