The trial was conducted during the Rabi season of 2022 to 2023 on the research farm of the Division of Vegetable Science at IARI, New Delhi, in a semi-arid subtropical climate with sandy clay loam soil classified as a Cambisol. Because the test accessions were too numerous to replicate individually, the team used an augmented block design: the four check varieties were replicated six times across six randomised blocks, while the remaining 90 accessions were distributed among the blocks, each block holding 15 test entries alongside the four checks. Plots were spaced at 30 centimetres between rows and 15 centimetres between plants, and standard fertilisation with farmyard manure, nitrogen, phosphorus and potassium was applied. Data were collected from five plants per plot and analysed with the augmentedRCBD package in R, which adjusts for block effects in unreplicated designs.

The laboratory work behind the study was extensive. Total phenolic content was measured with the Folin-Ciocalteu reagent method, expressed as gallic acid equivalents per 100 grams. Antioxidant capacity was assessed in two complementary ways: the DPPH radical scavenging assay, which tracks the bleaching of a violet free radical at 517 nanometres, and the ferric reducing antioxidant power, or FRAP, assay, which measures the ability of antioxidants to convert ferric to ferrous iron under acidic conditions, read at 593 nanometres. Total sugars were quantified with the anthrone reagent method, proteins by the DUMAS combustion technique, in which samples are burned at roughly 1000 degrees Celsius and nitrogen is measured by thermal conductivity, and minerals including calcium, magnesium, iron and zinc by atomic absorption spectroscopy after microwave digestion.

The results showed that genetic variation for nutritional quality in this germplasm is far larger than many earlier studies had suggested. Phenol content ranged more than six-fold, from 29.18 to 185.58 milligrams of gallic acid equivalents per 100 grams, with the line IPFD-16-13 recording the highest value and GP 1804 the lowest, against a mean of 70.74. Sugar content spanned 1.80 to 9.80 percent, with the check variety Pusa Prabal the sweetest at 9.80 percent and GP 1104 the least sweet. Protein, measured on a fresh weight basis, varied from 3.54 to 9.09 percent, with GP 1102 topping the entire panel at 9.09 percent and 2021/PMVAR-7 the lowest. Analysis of variance confirmed that treatment effects were highly significant for every trait evaluated, while block effects were non-significant, indicating that the augmented design effectively controlled field heterogeneity.

The mineral data were equally encouraging for biofortification. Calcium ranged from 8.04 to 33.49 milligrams per 100 grams and magnesium from 24.41 to 60.59, with GP 1102 again the leader for both. Iron varied from 0.76 to 3.05 milligrams per 100 grams, with 2021/PMVAR-6 accumulating the most, and zinc ranged from 0.52 to 3.12, with GP 1801 far exceeding all check cultivars. Iron and zinc deficiencies remain among the most widespread forms of hidden hunger worldwide, so identifying pea lines that naturally concentrate these micronutrients offers a low-cost route to nutrient-enriched cultivars. GP 1102 outperformed the best check for protein, calcium and magnesium simultaneously, making it a particularly valuable donor for overall nutritional density.

Antioxidant capacity told its own story. JP625 recorded the highest values in both the DPPH assay, at 0.83 percent Trolox equivalents, and the FRAP assay, at 0.99 micromoles of Trolox equivalents per gram fresh weight, while IPFD-16-13 and JP625 both showed substantially higher phenolic content than the best check. Correlation analysis revealed why phenolics matter so much here: phenol content was strongly and positively associated with both DPPH, at a coefficient of 0.633, and FRAP, at 0.709, indicating that phenolic compounds are the primary drivers of antioxidant activity in pea seeds. The two antioxidant assays also correlated strongly with each other, at 0.594, reinforcing the reliability of the measurements.

The correlation matrix also exposed trade-offs and opportunities that breeders will need to navigate. Protein content was positively associated with calcium, magnesium, iron, zinc and FRAP, but negatively correlated with moisture, pod yield per plant, DPPH and sugar. Sugar content, by contrast, correlated positively with pod yield, iron and moisture, suggesting that selection for sweeter, higher-yielding peas may run counter to selection for protein density. The strong positive relationship between protein and magnesium, at 0.808, is biologically plausible because magnesium is an essential cofactor in nitrogen assimilation and protein biosynthesis, meaning genotypes that accumulate more magnesium may simply be better equipped to synthesise protein. Moisture content showed strong negative correlations with most nutritional constituents, consistent with a dilution effect in which drier, more nutrient-dense seeds concentrate proteins and minerals on a fresh weight basis.

Multivariate statistics sharpened the picture further. Principal component analysis showed that the first two components together explained more than 50 percent of total variation, with the first five components accounting for 33.73, 18.38, 14.75, 12.74 and 6.61 percent respectively. The first principal component emerged as a nutritional-density axis, with positive loadings for protein, magnesium, phenolics and both antioxidant assays, effectively separating nutrient-dense genotypes from watery, lower-quality ones. Hierarchical clustering using Ward’s method and Euclidean distance grouped the 94 genotypes into six distinct clusters. The largest inter-cluster distance, 113.83, separated clusters 6 and 1, while cluster 4 contained the highest cluster means for protein, calcium and magnesium and included GP 1102, and cluster 6, which included JP625, recorded the highest phenol content and antioxidant activity. Crosses such as GP 1102 crossed with JP625 or IPFD-16-13 could combine superior protein and mineral content with enhanced antioxidant capacity, while GP 1102 crossed with GP 1801 or 2021/PMVAR-6 might improve protein and micronutrients together.

The authors are careful to frame these results as a starting point rather than a finished recipe. The study was conducted over a single growing season, and biochemical traits in peas are known to be environmentally responsive, so the genotype rankings reported here reflect performance under the specific conditions of the 2022 to 2023 Delhi winter rather than genetically fixed values. Multi-location and multi-year trials will be needed to confirm the stability of lines such as GP 1102 and JP625 before they enter commercial breeding programmes, and future work should profile the specific phenolic subclasses and individual sugars in the elite lines using chromatographic techniques such as HPLC-DAD or LC-MS. Still, the message is clear: within existing vegetable pea germplasm lies enough natural variation to breed peas that are sweeter, richer in protein and minerals, and packed with health-promoting antioxidants, all through conventional selection and crossing rather than genetic modification.

Subject of Research: Nutritional and biochemical evaluation of garden pea germplasm for quality breeding

Article Title: Nutritional and biochemical analysis in vegetable pea germplasm for quality breeding

Article References: Nutritional and biochemical analysis in vegetable pea germplasm for quality breeding. (n.d.). https://doi.org/10.1007/s44372-026-00912-6

Image Credits: AI Generated

DOI: 10.1007/s44372-026-00912-6

Keywords: garden pea, Pisum sativum, germplasm, biofortification, antioxidant activity, phenolic compounds, protein content, genetic diversity, plant breeding, mineral nutrients, principal component analysis, nutritional quality