Inoculating plant growth-promoting bacteria and arbuscular mycorrhiza fungi modulates rhizosphere acid phosphatase and nodulation activities and enhance the productivity of soybean (Glycine max)

Abstract

Soybean [Glycine max (L.) Merrill] cultivation is important for its dual role as rich source of dietary protein and soil fertility enhancer, but production is constrained by soil nutrient deficiencies. This is often resolved using chemical fertilizers that exert deleterious effects on the environment when applied in excess. This field study was conducted at Nkolbisson-Yaoundé in the agro-ecological zone V of Cameroon to assess the performance of soybean when inoculated with plant growth-promoting bacteria (PGPB) and arbuscular mycorrhiza fungi (AMF), with or without NPK fertilizer addition. Ten treatments (Control, PGPB, AMF, PGPB+AMF, PGPB+N, PGPB+PK, PGPB+N+PK, PGPB+AMF+N, PGPB+AMF+PK, and PGPB+AMF+N+PK) were established in a randomized complete block design with three replicates. Mycorrhizal colonization was only observed in AMF-inoculated soybean roots. In comparison to control, sole inoculation of PGPB and AMF increased the number of root nodules by 67.2% and 57%, respectively. Co-application of PGPB and AMF increased the number of root nodules by 68.4%, while the addition of NPK fertilizers significantly increased the number of root nodules by 66.9–68.6% compared to control. Acid phosphatase activity in soybean rhizosphere ranged from 46.1 to 85.1 mg h–1 kg–1 and differed significantly across treatments (p < 0.001). When compared to control, PGPB or AMF or their co-inoculation, and the addition of NPK fertilizers increased the acid phosphatase activity by 45.8%, 27%, 37.6%, and 26.2–37.2%, respectively. Sole inoculation of PGPB or AMF and their integration with NPK fertilizer increased soybean yield and grain contents (e.g., carbohydrate, protein, zinc, and iron) compared to the control (p < 0.001). Soil phosphorus correlated significantly (p < 0.05) with soybean grain protein (r = 0.46) and carbohydrate (r = 0.41) contents. The effective root nodules correlated significantly (p < 0.001) with acid phosphatase (r = 0.67) and soybean yield (r = 0.66). Acid phosphatase correlated significantly (p < 0.001) with soybean grain yield (r = 0.63) and carbohydrate (r = 0.61) content. Effective root nodules correlated significantly with carbohydrate (r = 0.87, p < 0.001), protein (r = 0.46, p < 0.01), zinc (r = 0.59, p < 0.001), and iron (r = 0.77, p < 0.01) contents in soybean grains. Overall, these findings indicate strong relationships between farm management practices, microbial activities in the rhizosphere, and soybean performance.

Introducing the Power of Plant Growth Promoting Microorganisms in Soilless Systems: A Promising Alternative for Sustainable Agriculture

“…By understanding the principle mechanism of rhizoengineers, we can see that improved crop performance results from genes in the microorganisms that are functionally related to promoting plant growth, altering root morphology, improving water translocation, and facilitating nutrient absorption and mineralization. Our search showed that the soilless observed trends in overall yield growth were similar to those reported in studies that employed PGPM in soil-based cropping systems; AMF inoculation in hydroponics, under reduced nutrient levels, increased the total yield by 49.54%, which is consistent with results obtained in soil cultivations (46-50% increase) [85]. In addition, endophytes were shown to increase total yield by 22.12%, just as demonstrated under limited-N soil conditions (31-39% increase) [86].…”

Drought-Tolerant Bacteria and Arbuscular Mycorrhizal Fungi Mitigate the Detrimental Effects of Drought Stress Induced by Withholding Irrigation at Critical Growth Stages of Soybean (Glycine max, L.)

“…In addition, the results showed that the mixture application showed higher nodule numbers as compared to the individual and dual applications. Similarly, Ngosong et al [ 62 ] found that the combination of PGPB and AMF resulted in a higher number of root nodules when compared to individual applications. Also, Ashwin et al [ 35 ] found that dual inoculation with rhizobia and AMF increased the number and weight of soybean nodules.…”

Combination of Liquid Organic and Chemical Fertilizer on Corn and Soybean Using Intercropping in Ultisols

“…According to [41], microorganisms Azospirillum, Azotobacter, Bacillus and Pseudomonas can increase nutrient availability and absorption, plant growth, and crop production. Azospirillum inoculant applied to the soil could increase soil fertility and maize production [42].…”

“…Soybean is a legume from the leguminous family. Soybean is rich in protein content, and planting soybeans can increase soil fertility [27]. One of the advantages of soybean plants is the ability to fix nitrogen from the air to the soil.…”