Ecological, morpho-agronomical, and nutritional characteristics of Sulla flexuosa (L.) Medik. ecotypes

Abstract

The present work was part of assessing wild genetic plant resources of forage interest in Northern Morocco and aimed to study the agro-morphology and nutritional value of Sulla flexuosa (L.) Medik. (Hedysarum flexuosum L.) ecotypes. The seeds of twenty-one wild S. flexuosa (L.) Medik. ecotypes were collected from 21 sites. The edaphic and climatic characteristics of the collection sites were studied and testified to the remarkable adaptability of S. flexuosa (L.) Medik. These 21 ecotypes were cultivated in three complete randomized blocks design for two consecutive years. Statistical analysis showed substantial variability between the collected ecotypes. Principal component analysis and heatmap analysis allowed to distinguish four groups of ecotypes mainly based on nutritional parameters (fiber content and digestibility), forage production (dry matter yield, number of leaves per plant, and total number of branches), and reproduction (number of inflorescences per plant and, weight of thousand seeds and seeds per plant). Furthermore, the present study pointed out the value of ecotype 1, which was dual purpose with its high productivity, nutritional value, and reproductive parameters. Ecotype 4 was also highlighted as having late flowering but intermediate productivity, which can be used mainly for haymaking as the drying period could coincide with the last rainfall in the region.

Figure 1

Collection sites of the 21 S. flexuosa (L.) Medik. ecotypes (This map was generated using ArcGIS Desktop version 10.4.1—Esri, Redlands, CA, USA, https://en.freedownloadmanager.org/Windows-PC/Portal-for-ArcGIS.html ).

Figure 2

Correlation matrix of agro-morphological and edapho-climatic traits evaluated in 21 Moroccan S. flexuosa (L.) Medik. ecotypes. Positive correlations are displayed in green and negative correlations in purple color. The color intensity and the size of the circle are proportional to the correlation coefficients. On the right side of the correlogram, the legend color shows the correlation coefficients and the corresponding colors. NPB Number of plagiotropic branches, PH Plant height (cm), LOA Length of the orthotropic axis (cm), LLPB Length of the longest plagiotropic branch (cm), NLP Number of leaves per plant, NIP Number of inflorescences per plant, NTB Number of total branches, SD Stem diameter (cm), FMY Fresh matter yield (T/ha), DMY Dry matter yield (T/ha), LSR Leaf to stem ratio, NDE Number of days to emergence (°C), FBA First bud appearance (°C), FDUR Flowering duration (°C), SWP Seed weight per plant (g), K Exchangeable potassium (ppm), FnSilt Fine silt (%), CoSilt Coarse silt (%), BIO4 Temperature seasonality (standard deviation × 100), BIO6 Minimum temperature of the coldest month (C°), BIO7 Average temperature of the wettest quarter (°C), BIO8 Average temperature of the wettest quarter (C°), BIO11 Average temperature of the coldest quarter (°C), BIO15 Precipitation seasonality (coefficient of variation, %), BIO18 Precipitation of warmest quarter (mm), BIO19 Precipitation of coldest quarter (mm).

Figure 3

The correlation matrix of nutritional and edapho-climatic traits evaluated in 21 Moroccan S. flexuosa (L.) Medik. ecotypes. Positive correlations are displayed in green and negative correlations in purple color. The color intensity and the size of the circle are proportional to the correlation coefficients. On the right side of the correlogram, the legend color shows the correlation coefficients and the corresponding colors. Ash (% DM), NFE Nitrogen-free extract (% DM), CF Crude fibers (% DM), NDF Neutral detergent fibers (% DM), ADF Acid detergent fibers (% DM), ADL Acid detergent lignin (% DM), IVEOMD Enzymatic organic matter digestibility (%), IVTD In vitro true digestibility (%), ME Metabolizable energy (MJ/kg DM), CT Condensed tannins (% DM), CoSilt Coarse silt (%), P Available phosphorus (ppm), BIO1 Average annual temperature (°C), BIO2 Average diurnal variation [monthly average (max temperature—min temperature)] (°C), BIO3 Isothermality (BIO2/BIO7 × 100)], BIO4 Temperature seasonality (standard deviation * 100), BIO5 Maximum temperature of the warmest month (C°), BIO7 Average temperature of the wettest quarter (°C), BIO13 Precipitation of wettest month (mm), BIO15 Precipitation seasonality (coefficient of variation), BIO19 Precipitation of coldest quarter (mm).

Figure 4

Graph of the variables and individuals of the principal component analysis. NLP Number of leaves per plant, SWP Seeds weight per plant (g), TSW Thousand seed weight (g), NIP Number of inflorescences per plant, NTB Number of total branches, SD Stem diameter (cm), DMY Dry matter yield (T/ha), CF Crude fiber (% DM), NDF Neutral detergent fibers (% DM), ADF Acid detergent fibers (% DM), ADL Acid detergent lignin (% DM), IVEOMD Enzymatic organic matter digestibility (%), NFE Nitrogen-free extract (% DM), ME metabolizable energy (MJ/kg DM), Hum. Humidity (%), FnSilt Fine silt (%), P Available phosphorus (ppm), EC Electrical conductivity (mS/m), OM Organic matter (%), BIO6 Min temperature of coldest month (°C), BIO12 Annual precipitation (mm), BIO13 Precipitation of wettest month (mm), BIO14 Precipitation of driest month (mm), BIO16 Precipitation of wettest quarter (mm), BIO17 Precipitation of driest quarter (mm), BIO18 Precipitation of warmest quarter (mm), BIO19 Precipitation of coldest quarter (mm). Four clusters were determined by the cluster heatmap analysis and represented via the four colored circles (green, purple, yellow, and blue) on this figure.

Figure 5

Cluster heatmap analysis of S. flexuosa (L.) Medik. ecotypes’ responses to morpho-phenological, agronomic, and nutritional characterization. The heatmap plot describes the relative abundance of each S. flexuosa (L.) Medik. ecotype (rows) within each trait (column). The color code (blue to dark red) displays the values of the parameters: blue color indicates high values while red color indicates low values. The dendrogram (on the left) shows the hierarchical clustering of S. flexuosa (L.) Medik. ecotypes based on the Euclidian distance and Ward’s clustering method. CF Crude fibers (% DM), NDF Neutral detergent fibers (% DM), ADL Acid detergent lignin (% DM), DMY Dry matter yield (T/ha), SD Stem diameter (cm), NTB Number of total branches, NLP Number of leaves per plant, EF End of flowering (°C), SF Start of flowering (°C), IVEOMD Enzymatic organic matter digestibility, ME Metabolizable energy (MJ/kg DM), TSW Thousand seed weight (g), NFE Nitrogen-free extract (% DM), FDUR Flowering duration (°C), SWP Seed weight per plant (g), NIP Number of inflorescences per plant.