Arbuscular Mycorrhizal Fungi (AMFs) could be used to sustainably improve crop yields. The present study evaluated the diversity of AMF species associated with soybean (Glycine max L. Merill) in main soybean-producing ...Arbuscular Mycorrhizal Fungi (AMFs) could be used to sustainably improve crop yields. The present study evaluated the diversity of AMF species associated with soybean (Glycine max L. Merill) in main soybean-producing areas in Benin. Composite soil samples from 13 production areas at a rate of 04 villages per production areas were collected. A spore trapping device was set up to reveal the diversity of spores. The physical and chemical properties of the soils, the frequency and intensity of mycorrhization of roots, and the diversity of AMF spores were determined in the soil samples following trapping. As result, eight morphotypes belonging to four genera: Glomus, Acaulospora Gigaspora and Disversispora and three families: Diversisporales, Glomérales and Paraglomérales were observed. An important variability of spore densities was observed from one production areas to another with a higher abundance in the production areas of Copargo estimated at 3584 spores/100g soil. The biological diversity indexes as Shannon (0.0311), Simpson (0.0204) and Hill (0.0235), varied significantly (p < 0.05) from one production areas to another. There was significant correlation between the parameters studied, particularly between the physico-chemical parameters of the soils and between the physico-chemical parameters and the biological diversity indexes. For the mycorrhization parameters, the mycorhization frequencies did not vary from one production areas to another, unlike the intensities, which significantly varied from one production areas to another (2.31% to 24.62%). Finally, this study revealed that the physico-chemical parameters of the soils had an influence on the other parameters studied. Moreover, there were an abundance and a significant diversification of AMFs associated with soybean in the different production areas, which are influenced by certain physico-chemical soil parameters.展开更多
Bambara groundnut [Vigna subterranea (L.) Verdc.], as a legume, can establish relationships with nitrogen-fixing bacteria such as Rhizobium. However, Rhizobium efficacy is not always optimal due to the lack or poor ef...Bambara groundnut [Vigna subterranea (L.) Verdc.], as a legume, can establish relationships with nitrogen-fixing bacteria such as Rhizobium. However, Rhizobium efficacy is not always optimal due to the lack or poor efficient strains in the soil. This study aimed to evaluate symbiotic efficiency of endogenous Rhizobia nodulating Bambara groundnut and their resistance to abiotic conditions. Root nodules were randomly sampled from three agroecological zones across the country, surface sterilized, ground and paste plated on YEMA media. After 24 hours, the bacterial colonies were purified. The pure cultures were further characterized using morphological and biochemical methods and their resistance to antibiotics and heavy metals was evaluated. Lastly, the symbiotic efficiency of the isolates was assessed through a greenhouse experiment. A total of eighty-five presumptive strains were isolated from Bambara groundnut roots nodules obtained from the farms. The physiological characterization of the isolated showed a decrease in isolates growth when NaCl concentration was more than 7%. In addition, 47% of the isolates were tolerant to a temperature of 40°C. Most of the isolates were highly resistant to Erythromycin in all its concentration levels and to Kanamycin, Spectinomycin, Neomycin and Ampicillin at 10 μg⋅mL<sup>−1</sup>. Most of them showed resistance to Cu and Zn at 10 μg⋅mL<sup>−1</sup>. Results of the effectiveness test on two Bambara groundnut varieties yielded dry shoot matter varying from 3.33 g⋅plant<sup>−1</sup> to 7.21 g⋅plant<sup>−1</sup> for variety 1 and from 4.38 g⋅plant<sup>−1</sup> to 8.38 g⋅plant<sup>−1</sup> on variety 2. N uptake ranged between 0.09 g⋅plant<sup>−1</sup> and 0.29 g⋅plant<sup>−1</sup> for variety 1 and between 0.12 and 0.29 g⋅plant<sup>−1</sup> for variety 2. The isolates yielding higher shoot dry weight and N uptake were LMSEM312, LMSEM338, LMSEM307, LMSEM351 for variety 1 and L展开更多
The runoff and soil loss were assessed <em>in situ</em> at the scale of 2.12 m<sup>2</sup> plots during the rainy season of 2010 to better understand the determinants and magnitude of the massi...The runoff and soil loss were assessed <em>in situ</em> at the scale of 2.12 m<sup>2</sup> plots during the rainy season of 2010 to better understand the determinants and magnitude of the massive soil loss and land subsidence (donga) in the sub-humid zone of Africa in Karimama, North Benin. The experimental design was a split plot with two factors: the topography in 3 modalities (upstream, center and downstream of the donga) was assigned as main plot factor and the degree of degradation of dongas in 2 modalities (beginner dongas and advanced dongas) was assigned as subplot factor. Runoff water was collected through a storage system composed of two tanks. Data were collected on 36 plots (9 plots per donga × 4 dongas). The runoff varies significantly from one site to another for the rainy episode of October 10, 2010. It is twice as high in land use areas (5.87 mm) as in W Park (2.32 mm;l.s.d. = 1.81 mm). From upstream to downstream, runoff and soil loss increased from 2.4 mm to 85.3 mm and 80 g<span style="white-space:nowrap;">·</span>m<sup>-2</sup> to 197 g<span style="white-space:nowrap;">·</span>m<sup>-2</sup>, respectively. Runoff is high in the early dongas (7.60 mm) and low in the advanced dongas (5.68 mm) in contrast to lower soil loss in the early dongas (34 g<span style="white-space:nowrap;">·</span>m<sup>-2</sup>) and high in the advanced dongas (237 g<span style="white-space:nowrap;">·</span>m<sup>-2</sup>). The low value of soil loss with respect to the magnitude of the phenomenon suggests the probable occurrence of other soil loss mechanisms to be elucidated.展开更多
文摘Arbuscular Mycorrhizal Fungi (AMFs) could be used to sustainably improve crop yields. The present study evaluated the diversity of AMF species associated with soybean (Glycine max L. Merill) in main soybean-producing areas in Benin. Composite soil samples from 13 production areas at a rate of 04 villages per production areas were collected. A spore trapping device was set up to reveal the diversity of spores. The physical and chemical properties of the soils, the frequency and intensity of mycorrhization of roots, and the diversity of AMF spores were determined in the soil samples following trapping. As result, eight morphotypes belonging to four genera: Glomus, Acaulospora Gigaspora and Disversispora and three families: Diversisporales, Glomérales and Paraglomérales were observed. An important variability of spore densities was observed from one production areas to another with a higher abundance in the production areas of Copargo estimated at 3584 spores/100g soil. The biological diversity indexes as Shannon (0.0311), Simpson (0.0204) and Hill (0.0235), varied significantly (p < 0.05) from one production areas to another. There was significant correlation between the parameters studied, particularly between the physico-chemical parameters of the soils and between the physico-chemical parameters and the biological diversity indexes. For the mycorrhization parameters, the mycorhization frequencies did not vary from one production areas to another, unlike the intensities, which significantly varied from one production areas to another (2.31% to 24.62%). Finally, this study revealed that the physico-chemical parameters of the soils had an influence on the other parameters studied. Moreover, there were an abundance and a significant diversification of AMFs associated with soybean in the different production areas, which are influenced by certain physico-chemical soil parameters.
文摘Bambara groundnut [Vigna subterranea (L.) Verdc.], as a legume, can establish relationships with nitrogen-fixing bacteria such as Rhizobium. However, Rhizobium efficacy is not always optimal due to the lack or poor efficient strains in the soil. This study aimed to evaluate symbiotic efficiency of endogenous Rhizobia nodulating Bambara groundnut and their resistance to abiotic conditions. Root nodules were randomly sampled from three agroecological zones across the country, surface sterilized, ground and paste plated on YEMA media. After 24 hours, the bacterial colonies were purified. The pure cultures were further characterized using morphological and biochemical methods and their resistance to antibiotics and heavy metals was evaluated. Lastly, the symbiotic efficiency of the isolates was assessed through a greenhouse experiment. A total of eighty-five presumptive strains were isolated from Bambara groundnut roots nodules obtained from the farms. The physiological characterization of the isolated showed a decrease in isolates growth when NaCl concentration was more than 7%. In addition, 47% of the isolates were tolerant to a temperature of 40°C. Most of the isolates were highly resistant to Erythromycin in all its concentration levels and to Kanamycin, Spectinomycin, Neomycin and Ampicillin at 10 μg⋅mL<sup>−1</sup>. Most of them showed resistance to Cu and Zn at 10 μg⋅mL<sup>−1</sup>. Results of the effectiveness test on two Bambara groundnut varieties yielded dry shoot matter varying from 3.33 g⋅plant<sup>−1</sup> to 7.21 g⋅plant<sup>−1</sup> for variety 1 and from 4.38 g⋅plant<sup>−1</sup> to 8.38 g⋅plant<sup>−1</sup> on variety 2. N uptake ranged between 0.09 g⋅plant<sup>−1</sup> and 0.29 g⋅plant<sup>−1</sup> for variety 1 and between 0.12 and 0.29 g⋅plant<sup>−1</sup> for variety 2. The isolates yielding higher shoot dry weight and N uptake were LMSEM312, LMSEM338, LMSEM307, LMSEM351 for variety 1 and L
文摘The runoff and soil loss were assessed <em>in situ</em> at the scale of 2.12 m<sup>2</sup> plots during the rainy season of 2010 to better understand the determinants and magnitude of the massive soil loss and land subsidence (donga) in the sub-humid zone of Africa in Karimama, North Benin. The experimental design was a split plot with two factors: the topography in 3 modalities (upstream, center and downstream of the donga) was assigned as main plot factor and the degree of degradation of dongas in 2 modalities (beginner dongas and advanced dongas) was assigned as subplot factor. Runoff water was collected through a storage system composed of two tanks. Data were collected on 36 plots (9 plots per donga × 4 dongas). The runoff varies significantly from one site to another for the rainy episode of October 10, 2010. It is twice as high in land use areas (5.87 mm) as in W Park (2.32 mm;l.s.d. = 1.81 mm). From upstream to downstream, runoff and soil loss increased from 2.4 mm to 85.3 mm and 80 g<span style="white-space:nowrap;">·</span>m<sup>-2</sup> to 197 g<span style="white-space:nowrap;">·</span>m<sup>-2</sup>, respectively. Runoff is high in the early dongas (7.60 mm) and low in the advanced dongas (5.68 mm) in contrast to lower soil loss in the early dongas (34 g<span style="white-space:nowrap;">·</span>m<sup>-2</sup>) and high in the advanced dongas (237 g<span style="white-space:nowrap;">·</span>m<sup>-2</sup>). The low value of soil loss with respect to the magnitude of the phenomenon suggests the probable occurrence of other soil loss mechanisms to be elucidated.
