Most of Melilotus Miller species, a forage legume, contain coumarin, an unfavorable component in their shoot. There is no information concerning coumarin on Iranian Melilotus germplasms. It is crucial for plant breeders to know the concentration of this component in the breeding materials, its relationship with other traits and with genotype geographic origin. In a two-year field study a total of 196 accessions of biennial Melilotus were planted in two replications in March 2014. Thirty-nine agro-morphobiochemical traits were recorded according to standard descriptors. Fluorescencemetery assay was applied to detect free, conjugated, and total coumarin concentrations in plant leaves. The data were subjected to correlation, path, regression, factor, and cluster analyses. Total coumarin concentration varied from 0.09 to 5.27% of leaf dry weight (LDW) with a mean of 1.63 ± 0.08% of LDW among accessions. In M. officinalis, correlation analysis showed no significant correlation between coumarin concentration and cotyledon, hypocotyl, and stem colors. Therefore, no early predicting trait was determined to estimate coumarin concentration in the early growth phases of the germplasms. A positive linear relationship between leaf area and total coumarin concentration was observed by path and regression analyses. Based on factor analysis and extracted bi-plot, the scatter of accessions with low coumarin and high forage yield was determined. Materials were divided into three groups by k-means cluster analysis. There was no clear pattern between coumarin concentration and genotype geographic origin. The findings could be utilized by Melilotus breeders to apply in their breeding programs.

Coumarin variation in Iranian biennial Melilotus genetic resources and its relationship with agro-morphophenological traits

White sweet clover (Melilotus albus) cultivation, despite its many positive features such as the high yield of green mass, as well as protein content, is currently not widespread. This study aimed to determine the effect of the different sowing densities (500, 1000, and 1500 seeds per m2) and harvesting at different growth stages (before budding, budding, and full flowering) on the quality of fodder from the white sweet clover (Adela variety). The field experiment was carried out in the years 2018–2020 in a split-plot design. Plant biometric measurements, green and dry yield, the content of total protein, crude fat, crude fiber, ash, macro and microelements, and coumarin content were determined. The results show that an increase in the sowing density significantly increased the plant population after emergence and green and dry matter. However, it does not affect the total protein, crude fat, crude fiber, ash, macro and microelements, and coumarin content. Harvesting plants at the flowering stage increased plant height and green fodder yield. Plants harvested at the prebudding phase were characterized by the highest share of leaves (40.3%) and were the most abundant in protein (21.7%) and minerals (ash content 12.71%). Unfortunately, sweet clover at this growth stage contained the highest level of coumarin, which limits its use in animal feed.

https://www.mdpi.com/2077-0472/12/5/575/pdf?version=1650513413

The Effect of Sowing Density and Different Harvesting Stages on Yield and Some Forage Quality Characters of the White Sweet Clover (Melilotus albus)

Sweet clover (Melilotus sp.) has recently been identified in Australia as a pasture legume potentially suited to saline land. Some Melilotus species have shown high herbage productivity under such conditions. However, Melilotus can contain high levels of coumarin that can be converted to dicoumarol upon fungal contamination (Sanderson et al. 1986). Dicoumarol is an anti-coagulant and is the cause of sweet clover poisoning in stock fed spoiled Melilotus hay (Yamini et al. 1995).

S Hughes

Papers

Variation in coumarin concentration between lines of Melilotus sp.