Deciphering agronomic traits, biochemical components, and color in unique green-seeded fenugreek (Trigonella foenum-graecum L.) genotypes

Abstract

Fenugreek is a high-value legume known for its potential to enhance human health and combat a variety of diseases and metabolic disorders. This versatile crop has demonstrated promising therapeutic effects in managing obesity, diabetes, cancer, and poor metabolism conditions that have become major global health concerns. Despite the availability of multiple pharmaceutical remedies for these ailments in the market, often times the heavy chemical doses are accompanied by side effects on human body. To investigate the agronomic traits, medicinal potential, and color of fenugreek seeds, this study was conducted and identified fenugreek genotypes with green seed color (GSF1 to GSF10), which can prevent the progression of aforementioned diseases without the hassle of side effects. Ten unique green-seeded fenugreek (GSF) genotypes were compared with five released varieties (yellow-seeded fenugreek; YSF1 to YSF5) as check. The genotypes were assessed during rabi season for 3 consecutive years (2021-22 to 2023-24) in semi-arid Eastern Plain Zone of Rajasthan, India. The findings exhibited that agronomically GSF performed well, almost at par with the YSF. Harvest index (23.21 ± 0.37%) is higher in GSF with very marginal differences in other agronomic traits. The medicinal potential of the GSF showed that GSF6 has nearly 1.5 to 2 times higher insulinotropic 4-hydroxyisoleucine (0.90%) levels compared to the YSF genotypes. This unique non-protein branched amino acid is found in fenugreek seeds. GSF1 has a high concentration of chlorophyll (0.45 mg/100 g), GSF10 has low diosgenin and high 4-OHIle (261.80 mg/100 g and 0.85%, respectively), and GSF9 has low total soluble sugars (TSS; 3.50%). Oil content, phenols, and proteins were found to be higher in GSF making it preferable over YSF. The study further revealed that darkness of green color in the seed is directly related to its chlorophyll content and is directly associated with higher content of 4-OHIle and lower TSS. Among the studied genotypes, harvest index is higher in green-seeded genotypes with maximum seed yield (2473.74 Kg/ha) in genotype GSF8. The superior genotypes GSF1, GSF6, GSF8, GSF9, and GSF10 developed in the study hold potential for future breeding initiatives, aimed at boosting medicinal value, nutritional quality, and productivity.

Keywords: PCA; cancer; harvest index; insulin-resistance; medicinal; obesity; seed color.

Figure 1

(A–C) Geo location of experimental site (India, Ajmer, ICAR-NRCSS), (D) Field view of experiment, (E) Seeds after harvesting and (F) Extract of seeds.

Figure 2

Meterological graph of 2021–22, 2022–23 and 2023–24 depicting (A) Temperature (°C) (B) Relative humidity (%) (C) Evaporation (mm/day) (D) Total weekly rainfall (mm).

Figure 3

Comparative violin and boxplots of different morphological traits in green and yellow seeded fenugreek genotypes (A). Plant height (CM), (B). Primary branches, (C). Secondary branches, (D) Pods per plant, (E) Pod length (cm), (F) Seeds per pod, (G) Seed yield (Kg/ha), (H) Straw yield (Kg/ha), (I) Biological yield (Kg/ha), (J) Harvest Index (%), (K) Test weight (gm), (L) Maturity days, (M) Days to flowering.

Figure 4

(A) Comparison of medicinal compounds, (B) Total Chl (mg/100 g) contents and (C) Comparative value representation for medicinal compound and chlorophyll content. [4-OHIle (4-Hydroxyisoleucine), TSS (Total soluble sugar), FAA (Free fatty acid), Chl (Chlorophyll content)].

Figure 5

Radar graph representing the mean score of green and yellow seeded fenugreek genotypes (A) L* (Lightness) (B) a* (Red-Green Axis) (C) b* (Yellow-Blue Axis) (D) h* (Hue) (E) C* (Chroma) (F) ΔΕ True green (G) ΔΕ True yellow (H) (Greeness Index) (I) YI (Yellowness Index).

Figure 6

(A) Scree plot, (B) Variable PCA and (C) PCA biplot of Agronomic, Biochemical and color attributes representing variability Plant height (PH), primary branches (PB), secondary branches (SB), number of pods per plant (PPP), pod length (PL), secondary branches per plant (SPP), days to flowering (DF), maturity duration (MD), seed yield (SY), straw yield (StY), biological yield (BY), harvest index (HI) and test weight (TW), 4-hydroxyisoleucine (4-OHIle), Chlorophyll (Chl), Free amino acids (FAA), Total soluble sugars (TSS), Green Seeded Fenugreek (GSF) and Yellow Seeded Fenugreek (YSF).

Figure 7

Correlation heat map for all studied traits among fenugreek genotypes PH (Plant height), PB (Primary branches per plant), SB (Secondary branches per plant), DF (Days to flowering), MD (Days to Maturity), PPP (Pods per plant), PL (Pod length), SPP (Seeds per pod), SY (Seed yield), BY (Biological yield), HI (Harvest index), TW (Test weight), 4-OHIle (4-Hydroxyisoleucine), TSS (Total soluble sugar), OC (Oil content), FAA (Free fatty acid), Chl (Chlorophyll content), L* (Lightness), a* (Red green axis), b* (Yellow blue axis), h (Hue), C (Chroma), E (Color difference), GI (Greeness index) YI (Yellowness index).

Figure 8

Two-way clustering heatmap for fenugreek genotype based on biochemical and seed color traits 4-OHIle (4-Hydroxyisoleucine), FAA (Free fatty acid), h* (Hue), GI (Greeness index), Total Chl (Total chlorophyll content), a*(Red green axis), YI (Yellowness index), b* (Yellow blue axis), C* (Chroma), L* (Lightness), E (Color difference), TSS (Total soluble sugar).

Figure 9

Regression analysis (A) Plant height (B) Primary branches per plant (C) Secondary branches per plant (D) Pods per plant (E) Pod length (F) Seeds per pod (G) Straw yield (H) Biological yield (I) Harvest index (J) Test weight (K) Days to flowering (L) Days to maturity (M) 4-Hydroxyisoleucine (N) Total soluble sugars (O) Disogenin (P) Free fatty acid.