Effects of plant population density and intercropping with soybean on the fractal dimension of corn plant skeletal images

Three-year field experiments were conducted to determine whether the tempor al pattern of fractal dimension (FD) for corn (Zea malls L.) plant structur e is altered by plant population density (PPD) or intercropping with soybea n [Glycine max. (L.) Merr.], and how changes in the FD are related to chang es in other canopy characteristics. Plants in monocropped corn and intercro pped corn-soybean plots were randomly sampled and labelled for later identi fication. Corn plant structure was photographed from the side that allowed the maximum appearance of details (perpendicular to the plane of developed leaves) and from two fixed sides (side 1: parallel to the row and side 2: p erpendicular to the row). Images were scanned and skeletonized, as skeletal images provide acceptable information to estimate the FD of plant structur e two-dimensionally by the box-counting method. Differences in the FD estim ated from images taken perpendicular to the plane of developed leaves were not significant among competition treatments. An adjustment of corn plants to treatments, by changing the orientation of the plane of developed leaves with respect to the row, was observed. Based on overall FD means, competit ion treatments were ranked as: high > normal approximate to intercrop appro ximate to low for side 1 and intercrop > low approximate to normal > high f or side 2. Leaf area index (LAI) and plant height had a positive correlatio n with FD. In contrast, light penetration had a negative correlation with F D. In conclusion, FD provides a meaningful and effective tool for quantifyi ng corn plant structure, measuring the structural response to cultural prac tices, and modelling corn plant canopies.