Agricultural scientists investigated how different micronutrients affect wheat growth and grain yield. They conducted three experiments in controlled greenhouse conditions using identical soil compositions except for the nutrients being tested.
Experiment 1: Zinc Supplementation
Researchers planted wheat seeds in 20 identical pots containing nutrient-depleted soil. The pots were divided into four groups (5 pots each), and each group received a different concentration of zinc sulfate solution:
Figure 1 shows the experimental setup used for each pot.
After 90 days, researchers measured plant height, number of grain heads per plant, and total grain mass per pot.
Table 1 shows the results of Experiment 1.
| Group | Zinc Conc. (mg/L) | Avg Plant Height (cm) | Grain Heads / Plant | Total Grain Mass (g/pot) |
|---|---|---|---|---|
| A | 0 | 42.3 | 2.1 | 18.4 |
| B | 25 | 58.7 | 3.4 | 31.2 |
| C | 50 | 61.2 | 3.8 | 35.8 |
| D | 100 | 54.1 | 3.0 | 27.6 |
Experiment 2: Iron Supplementation
Using the same experimental design as Experiment 1, researchers tested iron sulfate at four concentrations:
Table 2 shows the results of Experiment 2.
| Group | Iron Conc. (mg/L) | Avg Plant Height (cm) | Grain Heads / Plant | Total Grain Mass (g/pot) |
|---|---|---|---|---|
| E | 0 | 43.1 | 2.0 | 17.9 |
| F | 50 | 52.4 | 2.8 | 25.6 |
| G | 100 | 55.8 | 3.1 | 28.4 |
| H | 200 | 48.2 | 2.4 | 21.3 |
Experiment 3: Combined Micronutrients
Researchers tested whether combining zinc and iron would produce synergistic effects greater than either nutrient alone. They used the optimal concentrations identified in Experiments 1 and 2:
Figure 2 compares the total grain yield across the four treatment groups.
Note: The expected additive effect of combining zinc and iron (calculated as J + K − I = 47.2 g/pot) was greater than the observed combined effect (42.8 g/pot), suggesting a partially antagonistic interaction.