Cytogenetical Studies in the Genus <i>Citrullus</i>, III. Bitter Substances in Fruits of <i>C. colocynthis</i> Schrad. and <i>C. vulgaris</i> Schrad

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The bitter substance in the fruits of C. colocynthis and C. vulgaris was analysed by chromatographic technique. Only one compound was detected in the ripe fruit of C. No. 1 (2x & 4x). The junior author identified it as “Citbittol A”. The amount of bitter substance in the ripe fruit of tetraploids was nine times as high as that of diploids.In unripe fruits of C. No. 1 (2x), however, seven new bitter compounds were detected. These newly found bitter substances were called “Citbittol B, C, D, E, F, G and H”. The amount of bitter substance in unripe fruits was higher than that of the ripe fruits. The bitter substance in the unripe fruit decompose gradually as the fruits ripen. Four compounds were detected in the ripe fruits of V. No. 2 and 4. Although C. No. 4 belongs to C. colocynthis, bitter substances was not found in the ripe fruits in this exceptional case.Ripe fruits of di-, tri- and tetraploid interspecific hybrids obtained from all possible cross combinations among diploid and tetraploid strains of C. No. 1 and V. No. 1 contain a higher amount of bitter substance in the ripe fruit than C. No. 1.The segregation ratio 3 (bitter): 1 (non-bitter) for F2 population and 1 (bitter): 1 (non-bitter) for the testcross was indicated by chromatographic analysis of bitter substance in the ripe friuts of each individual. From this evidence, bitterness in the genus Citrullus was concluded to have monohybrid inheritance with dominance of the bitter character.