The variability of plant branching and structural properties: data analysis and modeling investigation of winter oilseed rape (Brassica napus)

Winter oilseed rape (Brassica napus) is an important annual crop in many parts of the world. Investigation of structural and developmental branching patterns could lead to improvements in rape breeding and cultivation, and furthermore could lead to improved methods to investigate tree branching patterns. We carried out two-year experiments with two rape plant cultivars for each year. The branches and pods of more than 50 rape plants were counted for each cultivar of each year. Additionally, 3D coordinates of plant structural elements were measured and modeled for four representative rape plants near the maturation phase of growth. For each cultivar, we found the mean number of primary lateral branches per plant was significantly different between different years, but within each year there were no significant differences in the distribution of primary branch number between the two cultivars. Results were different for the total number of all primary and secondary lateral branches per plant and the total number of pods on the main stem per plant. Their frequency distributions changed a lot between different years, cultivars and locations, although the mean values were not significantly different. The 3D measurements showed that azimuth angles of pods and branches were uniformly distributed over 360 degrees, and the inclination angles of pods were centered closely about zero degrees (horizontal). There are challenging aspects of plant structural measurement methodology and structural modeling that have yet to be resolved.