Descriptors for characterization and evaluation of bael (Aegle marmelos (L.) Correa ex Roxb.) germplasm for utilization in crop improvement

Indian bael (Aegle marmelos L. Correa) is an underutilized fruit tree native to India. India harbors a diverse array of genetic variations related to desirable horticultural traits. Assessing genetic variability for varietal improvement necessitates the use of descriptors that comprehensively capture both quantitative and qualitative morphological characteristics. In the present study, variability in 213 accessions of bael were assessed and precisely characterized for various qualitative and quantitative morphological traits. The predominant traits observed in most commercial bael cultivars, which are developed through selection, include a semi-spreading or spreading nature with thorns. The bael germplasm displayed considerable qualitative and quantitative differences in morphological traits, encompassing the leaf, thorn, flower, and fruit, highlighting the diversity present within different parts of the bael tree. Aspect ratio of leaf, which relates the diameter to length, is an important identifying feature. The higher aspect ratio indicates towards round or oblate shape, while lower ratio points towards oblong or oval/ovate fruit shape. However, the final shape depends upon the nature of their either ends (apex or base). Likewise, the contents of total soluble solids (pulp), total soluble solids (mucilage) ascorbic acids and TSS: acidity ratio in the studied genotypes varied from < 34 to > 38 degrees Brix, < 45 to > 50 degrees Brix, < 0.30 to > 0.48 per cent and < 110 to > 0.125, respectively. In response to the observed variability in various traits, a comprehensive set of 55 morphological descriptors has been proposed. These descriptors are intended for the characterization, evaluation, and identification of bael germplasm. They are anticipated to be valuable not only for aiding researchers in data interpretation but also for contributing to crop improvement efforts.