Introduction
Nitrogen is an essential macronutrient required for plant growth. However, excessive application of synthetic nitrogen fertilizers can lead to environmental degradation. The availability of nitrogen in leguminous plants can be enhanced by utilizing nitrogen-fixing bacteria such as Rhizobium. These bacteria capture atmospheric nitrogen and convert it into compounds that can be absorbed by plants. Improving nitrogen use efficiency through the optimization of organic fertilizers and nitrogen-fixing bacteria can enhance soil productivity and increase agricultural yields by up to 50%. Plant Growth – Promoting Rhizobacteria (PGPR) represent an innovation that utilizes rhizobacteria to fix atmospheric nitrogen. The application of PGPR at a concentration of 150 mL/L can reduce nitrogen fertilizer usage by up to 25%. The utilization of microbes isolated from edamame roots has demonstrated the presence of nitrogen-fixing bacteria carrying the nifH gene, which can increase soybean yield by up to 36.1%.
Furthermore, to achieve environmentally friendly cultivation techniques, the use of amino acids is a strategy to increase disease resistance and plant nutrient absorption. Amino acids from fish are a way of utilizing fish waste to produce liquid amino acids with high added value. Amino acids not only contribute to soil fertility and chlorophyll formation but also support root nodule formation in legume plants. Their potassium, protein, and other organic compounds make amino acids effective in accelerating growth and increasing plant resistance to pests and diseases.
Edamame (Glycine max L. Merril.) is a type of legume known for its premium quality and high economic value. Edamame is often consumed as a vegetable due to its rich nutritional content, including vegetable protein, essential amino acids, fiber, vitamins, and minerals. Climate change, which causes increases in temperature and light, is positively related to amino acid levels but negatively related to organic acids and nucleotides, thus affecting the quality and taste of edamame.
Materials and Methods
This research was conducted at the experimental garden of Jember State Polytechnic, East Krajan, Sumbersari, Sumbersari District, Jember Regency, East Java. From June to September 2025. The materials used in the research include edamame seeds of the R-305 variety, amino acid materials (fish, biofertilizer), PGPR materials (Edamame Roots, Molasses, EM4, Potatoes, Shrimp Paste, Pineapple, and Rice Bran), identification materials for PGPR bacteria from edamame roots (Glycine max L. Merril.). The tools used include hoes, buckets and lids, meters, sprayer tanks, mulch, knives, sickles, scales, litmus paper, nameplates, markers, raffia ropes, and label paper.
This study used a Factorial Randomized Block Design (RBD) with two treatments, namely the administration of fish amino acid concentration with 5 levels (0 ml/l as a control, 5 ml/l, 10 ml/l, 15 ml/l and 20 ml/l) and the application of edamame root PGPR with 2 levels (0 ml/l as a control and 150 ml/l), carried out 3 replications with a total of 30 experimental units. Amino acid application was carried out at the age of 14 HST, 21 HST, 28 HST and 49 HST. And the application of edamame root PGPR was applied at the age of 14 HST and 28 HST. The stages of this study include the manufacture of amino acids and PGPR, land preparation, planting, application of amino acid and PGPR treatments, maintenance, observation, data analysis. The variables observed in this study were plant height, number of leaves, root length, number of root nodules, root crown ratio, number of productive internodes, number of branches, total pod weight, and number of edamame pods. Soil analysis of total N and organic C content was carried out before and after planting using the Kjeldahl and Walky and Black methods, while available P and K analysis was only carried out after planting using the Bray and 25% HCl methods. Data obtained by Analysis of Variance (ANOVA). If the data results have a significant effect, a further DMRT test is carried out at a 5% level.
Results And Discussion
Plant growth variables
In growth variables including plant height, root nodules, crown-root ratio, root length and number of leaves. PGPR and amino acid treatments (Figure 1,2,3 and 4) showed no significant differences in all observations. PGPR is thought to be able to stimulate plant growth by providing and optimizing the absorption and utilization of nitrogen nutrients which are useful for increasing plant height and stimulating budding. In addition, plant population also affects plant growth. However, in this study the results were not significantly different because PGPR and amino acids are organic materials that have slow-release properties (slow availability) but can be available longer in the soil than inorganic fertilizers.
The availability of nitrogen by providing additional nitrogen fertilizer will affect the development of plant branches. In line with the findings. Increasing the number of branches in edamame plants allows for an efficient supply of materials needed for plant growth, through the process of nitrogen fixation from the air, phosphorus dissolution, and the influence of exudates from hormonal compounds such as cytokinins and auxins. These compounds can stimulate nutrient absorption and improve the process of photosynthesis, which ultimately supports increased growth and yield of edamame plants.
Production variables
The observation variable of the number of pods showed a significant difference after further testing with 5% DMRT as in Table 1. Amino acid treatment at a concentration of 20 ml/L showed the highest result, namely 102.65 pods, but was not significantly different from the concentration of 10 ml/L, namely 102.40. The increase in the number of edamame pods in the amino acid treatment was caused by the high protein content as an enzyme activator that can optimize the pod formation process.
| Treatment | Number of Pods |
| A4 (20 ml/l) | 102.65a |
| A2 (10 ml/l) | 102.40a |
| A3 (15 ml/l) | 91.80ab |
| A0 (0 ml/l) | 89.50ab |
| A1 (5 ml/l) | 79.80b |
In other production observation variables such as the number of productive segments and weight pods showed no significant difference in results (Figure 5 and 6). The increase in the number of pods in amino acid treatment did not correlate with increased pod weight, this was because the rate of pod filling was followed by remobilization of dry weight and N from the crown to the seeds so quickly that not all pods were fully filled. According that, edamame plants will grow well if the required nutrients are sufficient and balanced.
N total and C/N
Based on laboratory results conducted before and after planting. The regression equation obtained for the variables N total and C-Organic on the total pod weight variable is as follows:
Y = 12.46+0.12X1+0.05X2
The regression model above can be interpreted as follows:
- The constant in the regression equation explains that if the total N variable (1) and the organic C variable (X2) are constant, then edamame production is 12.46 tons.
- The regression coefficient for the total N variable of 0.12 indicates that total N has a positive effect on edamame production. This means that higher total N can increase edamame production.
- The regression coefficient for the total C organic of 0.05 indicates that organic C has a positive effect on edamame production. This means that higher organic C can increase edamame production.
This is consistent with statement that N availability during the growth phase is positively correlated with crop yield. N application at planting time is recommended to increase yield and efficiency of edamame cultivation without compromising quality. Soil organic carbon content increases with the addition of organic matter. The C/N ratio affects nutrient availability because C/N is inversely proportional to nutrient availability. If C/N is too high, nutrients are less available to plants, whereas if C/N is low, nutrient availability will increase. This aligns with the opinion that low C/N content (<2%) will cause unstable soil aggregates. Topsoil is optimal for plant life with 5% organic matter.
Pod filling is followed by rapid remobilization of dry matter and N content from the crown to the seeds, which occurs before all pods are completely filled. Amino acids from fish contain a complete range of NPK nutrients, making them widely used to increase the productivity and fertility of soils that have declined in quality. Furthermore, it is a good source of minerals for the soil. Minerals function as indicators of nutrient load and indicators of food reserves in meeting the energy needs of plants.
Conclusion
The treatment of amino acid concentration with 10 ml/l showed significantly different results on the number of pods. The combination of amino acid and PGPR treatments showed a regression equation Y = 12.46 + 0.12X1 + 0.05X2, where total N and organic C contributed positively to increasing edamame plant production.
If you are interested in natural nitrogen or amino acid fertilizers, you are welcome to contact the Dora team.
