Morphological characterization of different accessions of bittergourd (Momordica charantia L.) and determination of their total alkaloid and saponin content

This study was conducted to characterize morphologically, determine the total amount of alkaloid and saponin content, and assess the genetic diversity of 15 accessions of bittergourd (Momordica charantia L.). Morphological characterization resulted in the identification of distinct characters of each accession and revealed the presence and absence of variants for a range of characters. Alkaloid content ranged from 73.74 to 111.76 mg/g with Bonito and Mayon varieties containing the most and least amounts, respectively. ANOVA however revealed no significant differences for the computed alkaloid values. Significant differences were found in the saponin content which ranged from 4.3314 to 10.2922 g/mg. Native varieties generally have higher saponin content than the commercial hybrids and improved open-pollinated (OPs) varieties. Makiling, the most studied and commonly used variety for pharmaceutical extraction purposes, had relatively low values for both alkaloid saponin contents. Leaf size was found to be negatively correlated with alkaloid content. Significant negative correlations were also obtained between saponin content and fruit shape, fruit luster, and fresh weight. Flesh color and flesh color intensity however, exhibited significant positive correlations with saponin content. All other characters showed no significant correlations with saponin and alkaloid content. Analysis of genetic diversity levels showed moderate to high diversity for majority of the characters examined. Standardized H' values ranged from 0.353 to 0.997 for qualitative characters and 0.800 to 0.964 for quantitative characters. Multivariate analysis revealed the relative genetic distances among the 15 accessions. The native, hybrid and OPS were separated into clusters at certain distances while the wide variety consistently showed a notable distance from the rest of the accessions owing to its many unshared characteristics. Results obtained in this study provided a basis for plant breeders what characters can be manipulated to increase alkaloid and saponin content in bittergourd and can serve as reference for the selection of varieties appropriate for pharmacological extraction.