Physiological characterization of bael genotypes of sub-tropical region of India for cold hardiness and fruit quality

A study was conducted during 2022-2024 for identification and characterization of bael accessions for cold hardiness, high yield and better fruit quality based on pooling of two years' data in ICAR-Central Institute for Subtropical Horticulture, Rehmankhera, Lucknow, (UP) having 26 degrees 9' N latitude and 80 degrees 77 E longitude with an altitude of 121 m above mean sea level. The experimental design employed to evaluate Bael germplasm was a Randomized Block Design (RBD). Phylogenetic tree analysis and Bi-plot analysis of bael accessions showed that lot of variability exists among bael accessions based on physiological, biochemical traits and quality attributes. Genotype viz. T-33 (3.02 mg g-1 FW), T-34 (1.61 mg g-1 FW), CISH B - 1 (3.91 mg g-1 FW) and S-4 (3.13 mg g-1 FW) have higher chlorophyll (total) content and photosynthetic rate as compared to other bael accessions which provides the basis for their better adaptability for cold temperature. Based on membrane stability index which was higher in CISH B-1 (81.08%), T-33 (84.74%), T-34 (78.46%) and S-4 (88.19%) as compared to other bael accessions, seems to be cold tolerant than the others. Principal Component Analysis (PCA) revealed two principal components (PCs) with varying explanatory power i.e. PC-1 accounted for 27.89%, PC-2 for 16.98% of the total variability.. Further, total yield was also higher in these accessions (55.61, 33.25, 47.56 and 30.73 kg tree-1, respectively). Moreover, fruit quality traits like total sugar, Vitamin C (17.34, 20.87, 20.44 and 12.47 mg per 100 g pulp), and TSS was higher in T-33 (37.46 degrees B), T-34 (34.02 degrees B), CISH-B1(35.00 degrees B) and S-4 (33.99 degrees B) while the content of phenol and titratable acidity was low. Further, across all the traits, the phenotypic coefficient of variation (PCV) was consistently greater than the genotypic coefficient of variation (GCV), indicating substantial inheritable genetic variance in fruit weight, number of seeds per fruit, and yield, making them suitable for breeding selection. Overall, study warrant that lot of genetic diversity exist among bael accessions in terms of physiological, biochemical and quality traits that creates an opportunity for the breeder to design climate resilient bael genotype with higher yield and improved fruit quality. This research identifies promising accessions of the underutilized crop like bael, which can be harnessed to provide cold resistance, offering opportunities for breeding climate resilient cultivars with enhanced productivity and fruit quality.