Genetic diversity assessment of bael (Aegle marmelos) varieties using morphometric, yield, and quality traits under semi-arid conditions

Abstract

Bael (Aegle marmelos (L.) Correa) is a magnificent but underrated fruit species with medicinal and religious value. This study used 36 morphological, yield, and fruit quality variables to investigate the genetic diversity of 21 bael cultivars in rainfed, hot, semi-arid climates, including a local genotype and a national check (NB-5). Important characteristics such fruit color, shape, size, locule arrangement, thorn, seed, and fiber quality were found to exhibit morphometric variability. Principal component analysis (PCA) revealed that the first eight components described 87.50% of the overall variation, with the first component alone explaining 32.42%. Fruit weight and pulp weight were strongly and positively correlated with total and non-reducing sugars (r = + 1.0). Hierarchical clustering grouped the cultivars into three distinct clusters, Cluster I (varieties 1, 3, 5, 6, 7, and 9) exhibited higher means for fruit width, girth, weight, shell weight, and shell thickness, making them suitable candidates for yield-based selection. Cluster III cultivars demonstrated superior qualitative traits, including elevated levels of ascorbic acid, non-reducing sugar, total sugar, antioxidants, total phenolics, total flavonoids, and total soluble solids. These results are useful for selecting and breeding bael varieties with improved quality and production traits, as well as creating functional foods and nutraceuticals made from bael because of its therapeutic qualities. Future studies may concentrate on using the best cultivars found to extract and market bioactive substances that may have therapeutic uses. Lastly, the great genetic diversity of bael cultivars highlights their potential for both economic exploitation and genetic improvement, especially in dry and semi-arid environments.

Keywords: Aegle marmelos; Genetic diversity; Morphology; Phytochemical traits; Principal component analysis.

Fig. 1

Varietal block of bael in field repository of Station, A: growth stage of tree, B: fruit development Stage, and C: ripening stage of fruit under field condition

Fig. 2

Floral structure, pollination, growth, and developmental stages of bael fruit; (A). Unopened flower buds; (B). Anthesis in herkogamous flower; (C) Complete opened flower; (D). Honeybee pollinating bael flower; (E). Fruit setting; (F), (G), and (H). Fruit development stages; (H). A tree laden with matured fruits, and (I). Ripened fruits ready for harvesting

Fig. 3

Shape of leaf base observed in different varieties

Fig. 4

Leaf apex shape noted in different bael varieties

Fig. 5

Leaf margin variations in bael varieties

Fig. 6

Trunk bark colour variation in bael varieties

Fig. 7

Locule arrangement in bael varieties

Fig. 8

Variations in thorn characters

Fig.9

Seed character

Fig. 10

Fibre colour in different bael varieties

Fig.11

Fruit shape, size and ripened fruit colour and surface texture of bael varieties under rainfed semi-arid conditions of western India

Fig. 12

Yield variability in 21 bael varieties (q/ha)

Fig. 13

Correlation heatmap among thirty-six morphological, yield and fruit quality characters of the twenty-one A. marmelos varieties including 1 promising line and one local genotype

Fig. 14

Variable correlation heatmap among thirty-six morphological, yield and fruit quality characters of the twenty-one A. marmelos varieties including 1 promising line and one local genotype

Fig. 15

The principal component analysis (PCA-biplot) for thirty-six morphological, yield and fruit quality characters of the twenty-one A. marmelos varieties including 1 promising line and one local genotype in two factors

Fig. 16

The principal component analysis (PCA-plot) representing all the varieties and genotypes for thirty-six morphological, yield and fruit quality characters on two axes (vertical and horizontal)

Fig. 17

Hierarchical Clustering Heatmap (HCH) represents thirty-six morphological, yield and fruit quality characters of the twenty-one A. marmelos varieties including 1 promising line and one local genotype

Fig. 18

Faceted density plot represents thirty-six morphological, yield and fruit quality characters of the twenty-one A. marmelos varieties including 1 promising line and one local genotype