Quantifying the Leaf Variegation In Red-Pigmented Aglaonema Cultivars Using Image Color Analysis

Abstract

Aglaonema cultivars, the red-series in particular, has gained attention in the recent past with a high demand in the floriculture trade as a foliage ornamental plant. Aglaonema plants are valued based on their foliar variegation trait which is placed as the second most important consideration in the purchase decision at commercial scale. In quantifying the amount of variegated colour on leaves, a simple and efficient technique is required, especially at the export market. In this study, we attempted to develop a simple and effective method to quantify the amount of variegated colour on leaves. Image colour analysis was performed using thirteen red-pigmented Aglaonema cultivars. Using a digital camera, the images of the variegated leaves were imported into a computer. Pixel value of each colour within the selected leaf area was determined using MatLab software and respective RGB measurement graphs were generated for each sample. RGB histograms were built on the colour values 0-255 (x-axis) and relative numbers of pixels at each of the 255 colour value (y-axis). The dendrogram for the selected 13 newly introduced red pigmented Aglaonema cultivars was derived from the RGB peak colour values. All the cultivars used generally had redpink and yellow patches on leaf blade. Three main clusters were observed at the similarity percentage of 66%. Leaf samples under each cluster show similar graph patterns in RGB measurement. In most of the samples, dark red color was observed and all the leaf samples indicated having dark green colour variegations. Blue colour was not visual in the leaves. Image colour analysis qualifies as a valuable new tool for accurate, reproducible detailed and objective quantitative assessment for monitoring changes in colours and variegation patterns of plants like Aglaonema.