This research attempts to systematically establish shape descriptor states through elliptic Fourier analysis (EFA) using pili (Canarium ovatum Engl.) kernel as a model. Kernel images of 53 pili accessions from the National Plant Genetic Resources Laboratory (NPGRL), University of the Philippines Los Baños were acquired using VideometerLab 3. Shape features, such as roundness, compactness and elongation, were extracted from the images. Shapes outlines were characterized using elliptic Fourier coefficients calculated from SHAPE version 1.3 software. Principal component analysis and cluster analysis were used to elucidate clusters representing the shape descriptor states. The first principal component accounts for the variation in length to width ratio; whereas, the second and third principal components explain the variation in the location of the widest portion and the truncation of the apex and base of the kernel, respectively. Cluster analysis separated the different accessions into six distinct clusters at 0.04 Euclidian distance. Six descriptor states, narrowly elliptic, elliptic, widely elliptic, ovate, obovate and lance-ovate, were characterized from the shape outlines and visualized through R's shape on r package. The discrimination between clusters was validated through MANOVA and LDA with 95% correct classification. The Fourier coefficients were also able to represent the variation observed from the physical properties of shape. The method may be used in establishing shape descriptors of all plant parts of all crop species.

A systematic method for determining colour descriptor states using image analysis is proposed using pili (Canarium ovatum) as a model. Kernel images of 52 pili accessions from the core collection of the Institute of Crop Science and National Plant Genetic Resources Laboratory, University of the Philippines Los Baños were captured using a calibrated VideometerLab 3 setup. Colour descriptor states were derived from the average International Commission on Illumination lightness (L*), green–red (a*) and blue–yellow (b*) colour component values. Cluster analysis and subsequent colour-parameter averaging per cluster were performed to produce representative colour values of descriptor states. The Euclidian distance (Delta E) of 3.5 was used to cut the cluster into readily distinguishable colour differences resulting to three descriptor states – light brown, brown and dark brown. Continuous colour variation of brown colour was observed indicating a possible quantitative nature of the trait. The use of delta E in elucidating the descriptor lists served as a gauge in successfully identifying distinguishable variations between colours. The method described can be applied to the elucidation of colour descriptor states of all parts of the plant of all crop species.

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