Analysis of variance (ANOVA)
Statistical analysis using ANOVA demonstrated significant differences among the Kodo millet genotypes for most nutritional traits except carbohydrate (Table 1). The existence of significant variation among nutritional parameters indicates the possibility of selecting superior genotypes for quality improvement and breeding program.
Significant variation was observed among the eleven kodo millet genotypes for nutritional traits, indicating the existence of valuable genetic diversity for quality improvement (Table 2). Among the evaluated genotypes, RK250-90 recorded the highest protein, iron and ash contents, suggesting its potential as a nutritionally superior genotype. KMV3, KMV4 and KMV9 demonstrated favorable nutrition profiles by combining higher protein with moderate to high carbohydrates and mineral contents. Whereas, lowest nutritional values has been observed in KMV1 genotypes. These variations demonstrates that these genotypes will be used as valuable genetic resources for breeding programs for improving nutritional quality in Kodo millet. Similarly,
Upadhyaya et al., (2014) emphasized the importance of exploiting genetic diversity in millet germplasm for nutritional enhancement.
Principal component analysis (PCA)
Principal component analysis is widely recognized as a robust multidimensional statistical tool for assessing genetic diversity and identifying nutritionally superior germplasm based on multiple quantitative traits simultaneously
(Upadhyaya et al., 2014; Jolliffe and Cadima, 2016). In this regards, PCA was performed to examine relationships among nutritional traits and to identify patterns of variability among Kodo millet varieties. The PCA plot revealed variation among the genotypes, as evidenced by their wide distribution across the first two principal components (Fig 1). Varieties positioned closer together demonstrated similar nutritional characteristics, while those located farther apart showed greater divergence. Among the evaluated genotypes, RK250-90 separated distinctly from KMV genotypes and occupied the upper left quadrant of the PCA plot. This isolated position indicates that RK250-90 has a unique nutritional profile as it contain comparatively higher protein and mineral values as compared with other genotypes. This diverse position suggest that this genotype may represent an important donor genotype for nutritional improvement programs. Similarly, KMV1 was positioned independently on the extreme positive side of PC1, indicating considerable divergence from other genotypes and may represent another valuable source of genetic variability.
KMV2, KMV3 and KMV8 formed a compact cluster in the positive region of the PCA plot indicating close nutritional similarity among these genotypes. KMV4, KMV9 and KMV10 were grouped together on the negative side of PC1 showing their comparable nutritional composition. Similar clustering patterns have been reported in diversity studies of millets and other cereal crops
(Upadhyaya et al., 2014; Goron and Raizada, 2015). KMV6 occupied an intermediate position whereas, KMV3 and KMV7 occupied separate position towards the lower region of PC2 indicating moderate divergence from the remaining genotypes
(Patil et al., 2019; Porwal et al., 2023). The significant variation in nutritional composition of grains among millet genotypes is governed by genetic factors and can be effectively exploited in breeding programmes for nutritional improvement and biofortification
(Upadhyaya et al., 2014; Goron and Raizada, 2015;
Nirubana et al., 2021). Developing cultivars with improved protein and micronutrient contents has become increasingly important in addressing hidden hunger, malnutrition problems and improving nutritional security, particularly in regions where millets constitute an important component of the daily diet (
Food and Agriculture Organization, 2023; International Crops Research Institute for the Semi-Arid Tropics, 2023;
Thakur and Saini, 1995;
Vishnuprabha and Vanniarajan, 2018).
Correlation analysis of nutritional traits
The heatmap illustrates the correlation among different nutritional traits of kodo millet varieties, namely protein, carbohydrate, fat, iron and ash content (Fig 2). Protein exhibited a strong positive association with iron (r=0.68) and ash (r=0.76) content, indicating that varieties with higher protein levels also tended to possess greater mineral content. This relationship suggests that simultaneous improvement of protein and iron through selection may be feasible, which is advantageous for breeding nutritionally superior cultivars (
Goron and Raizada, 2015). Iron also showed a moderately strong positive correlation with ash (r=0.62), revealed the contribution of mineral accumulation to the total ash content of the grain. Similar positive associations between mineral content and ash have been reported in cereal grains and millets, suggesting ash serve as an indicator of total mineral composition
(Saleh et al., 2013).Fat displayed moderate positive correlation with ash content but weak association with iron and carbohydrates. Carbohydrate showed a weak or negative relationship with iron, suggesting that higher carbohydrate concentration may not contribute to increased iron accumulation
(Yadav et al., 2020). Overall, the heatmap reveals the interrelationship among nutritional parameters and helps identify traits that can be simultaneously improved in breeding programs for nutritionally superior kodo millet varieties.
Cluster analysis of kodo millet varieties
Hierarchical cluster analysis (HCA) was performed using nutritional parameters to assess the similarity among the eleven Kodo millet germplasm. The dendrogram classified the varieties into two clusters represent variability among different kodo millet varieties based on their nutritional characteristics (Fig 3). The varieties were grouped according to their similarity, where closely linked varieties indicate similar nutritional composition. The clustering pattern reflects the degree of similarity among the varieties, where shorter linkage distances indicate greater nutritional resemblance while longer distances represent higher divergence (
Mohammadi and Prasanna, 2003).
The first cluster (cluster 1) contains KMV1, KMV5, KMV2 and KMV8. Within this cluster, KMV2 and KMV8 were most closely related varieties, joining at the lowest linkage distance, suggesting that these genotypes possess highly similar nutritional composition. KMV5 subsequently clustered with this pair, while KMV1 joined at a comparatively higher linkage distance, indicating that although nutritionally related, it is relatively more distinct than the other genotypes of this cluster. The second cluster (Cluster II) consisted of RK250-90, KMV3, KMV7, KMV4, KMV9, KMV10 and KMV6. In this cluster, KMV3 and KMV7 formed the closest pair indicating a high degree of nutritional similarity. KMV4and KMV9 clustered together at a short linkage distance, suggesting similar nutritional profiles. KMV10 and KMV6 also formed a closely related subgroup, reflecting comparable nutritional characteristics. These three sub-group were subsequently merged to form the larger cluster II.
The present investigation highlights the nutritional significance and variability among different Kodo millet genotypes. Future research may focus on molecular characterization of nutritionally superior genotypes to identify genes associated with enhanced protein and mineral accumulation. Such studies can support marker-assisted breeding and genetic improvement programs. Processing techniques including germination, fermentation, malting and extrusion may be optimized to enhance nutritional quality and functional properties of foods based on millets
(Dekka et al., 2023). Development of value-added meal products may help increase consumer awareness and commercial utilization of Kodo millet. Shelf-life studies and storage behavior of millet grains and processed products should also be investigated to improve product stability and marketability. Multi-location and multi-season trials involving larger germplasm collections are required to evaluate genotype x environment interactions affecting nutritional traits. Integration of advanced statistical tools, genomics, metabolomics and precision breeding approaches may further accelerate the development of high-yielding and nutritionally superior Kodo millet cultivars suitable for sustainable agriculture and nutritional security.