Includes bibliographical references.

Buckwheat is a multipurpose, dicotyledonous crop belonging to Polygonaceae. It encompasses over 20 species with two commonly cultivated species i.e. Common buckwheat (Fagopyrum esculentum Moench.) and Tartary buckwheat (Fagopyrum tataricum Gaertn.). It is a short duration crop with high adaptability to harsh environments. Buckwheat is rich in starch, proteins, antioxidants, trace elements, and dietary fiber with numerous medicinal properties. Despite its versatility and nutritional richness, its cultivation has declined due to lower productivity and profitability compared to high-value crops. Being an under-utilized and lesser-known crop, limited information is available on its genetic diversity and nutritional content. Considering the need to understand the diversity present in buckwheat genotypes for potential future crop improvement programs the study was conducted with the objective to assess diversity using morphological, biochemical, and molecular characteristics. The study aimed to characterize buckwheat germplasm based on morphological descriptors, genetic analysis, and biochemical traits. In all, 104 genotypes from various geographic regions were collected from NBPGR, Shimla were evaluated at the experimental farm (plant breeding, ICAR-RC NEH) for 18 morphological characters. Petiole length, cyme length, and yield per plant were found to have high PCV, GCV, heritability and genetic advance. The highest positive direct effect on yield was observed through the number of seeds per plant and the 100 seed weight. Genotypes from Cluster II could be directly used in hybridization programs to develop high-yielding lines ideal for the midhill regions of Meghalaya. Through molecular analysis, polymorphic SSR markers were found with an average PIC of 0.32, with Fes140, Fes3256 and Fes3508 emerging as the most promising primers for diversity studies. The AMOVA indicated that there was a major genetic variation among the individuals (80%) and very little among the populations (1%). Cluster analysis and Principal coordinate analysis separated accessions based on species rather than geographical region. Two subpopulations were found using population structure analysis with minimal genetic diversity change across geographical regions indicating frequent seed exchange or recent extensive cultivation and selection. The biochemical analysis of the selected genotypes for phytic acid, protein, and carbohydrates among the accessions revealed significant variation. The Tartary buckwheat showed comparatively high carbohydrate, protein, and phytic acid content as compare to common buckwheat. Among common buckwheat, EC18771 had the highest carbohydrate content, IC107238 was the highest protein, and IC107265 was the lowest phytic acid. Form Tartary buckwheat, IC24297 had the highest carbohydrate, EC18769 was the highest protein, and IC26596 was the lowest phytic acid. Considering high mean yield and stability across all three environments as per AMMI and multi-trait stability index analysis IC13141, IC49667, IC26587, IC107983, and IC107981 are identified as the best genotypes. These accessions can be of vital significance for future buckwheat breeding programs. The traits showing correlation as well as direct effect on yield per plant, could be relied upon as selection parameters for yield improvement in buckwheat. Additionally, the marker with high PIC will aid in better distinguishing between individuals. The buckwheat accessions are also rich source of carbohydrate and protein as compared mainstream cereal crops. Overall, the study offered intriguing details about the diversity of morphological traits, genetic diversity, and biochemical content in F.esculentum and F.tartaricum accessions. The findings from the current study will form a favorable base for genetic resource management, improved cultivation and applications of buckwheat at the commercial level in mid-hill regions of Meghalaya.