Morphological characterization of first selfing generation melon (Cucumis melo L.) genotypes

Abstract

The first selfing generation (S1) in melon breeding may still exhibit phenotypic variation because the materials are not yet genetically fixed. Morphological characterization at this stage is therefore useful to document visible variation before further evaluation in later generations. This study characterized qualitative and quantitative morphological traits of ten S1 melon genotypes. The experiment was conducted from May to August 2025 under greenhouse and laboratory conditions, using a Completely Randomized Design with 10 genotypes and 3 replications. Qualitative traits were characterized using melon descriptors, while quantitative traits were analyzed using analysis of variance followed by the Honestly Significant Difference test at the 5% level. Representative external and internal images of fruit were used to support visual documentation. The evaluated genotypes showed variation in fruit shape, fruit base and apex shape, rind ground color, groove and netting characteristics, flesh color, and seed color. Significant differences among genotypes were observed for internode length, leaf blade area, fruit harvest age, fruit diameter, fruit length, fruit weight, and flesh thickness. These findings show that the evaluated S1 melon genotypes remained phenotypically variable and require further evaluation in later selfing generations.