Foliar Nutritive Strategies for Superior Seedling Vigor: Synergistic Effects of Chelated Iron and Magnesium Sulphate on Improving Growth and Nutritional Status of Nemaguard Peach Rootstock Seedlings

In the world of fruit farming, the journey of a peach tree begins long before the first blossom appears. It starts with the rootstock, the sturdy foundation upon which the prized fruit-bearing variety is grafted. Among the many options available to growers, a specific type known as Nemaguard is highly prized for its ability to grow vigorously and resist harmful soil pests. However, getting these young seedlings to a size large enough for grafting can be a slow and difficult process. Nurseries often face the challenge of feeding these young plants enough nutrients to thrive, especially when the soil itself cannot provide everything the plant needs quickly. This is where the science of foliar fertilization comes in. Instead of relying solely on the roots to pull nutrients from the ground, this technique involves spraying a liquid nutrient solution directly onto the leaves. The leaves act as a direct gateway, absorbing these essential elements rapidly to fuel growth. Two specific nutrients are particularly vital for this process: magnesium, which sits at the very heart of the green pigment that captures sunlight, and iron, which helps the plant move energy and build proteins. Without enough of these, a plant struggles to grow tall or produce strong stems.

Researchers at the National Research Centre in Egypt set out to find the perfect recipe for feeding these young Nemaguard seedlings. Over the course of two growing seasons, they conducted a careful experiment to see how different amounts of chelated iron and magnesium sulphate, when sprayed onto the leaves, would affect the health and speed of growth of the young trees. They worked with seedlings that were two years old, placing them in large plastic pots filled with soil. The team divided the plants into groups, spraying some with plain water as a control, while others received specific doses of iron or magnesium. The iron was applied in three increasing strengths, and the magnesium was also tested at three different levels. Each group received three sprays during the season, with two weeks between each application, starting in mid-June. The researchers then waited two months after the final spray to measure the results, looking at everything from how tall the seedlings grew to how many leaves they produced and what nutrients were stored inside them.

The results painted a clear picture of how these nutrients transformed the young plants. Every group that received a nutrient spray grew significantly better than the group that received only water. The plants that were sprayed with magnesium sulphate at a concentration of 3 grams per liter showed the most dramatic improvement in physical size. These seedlings reached heights of 114 centimeters in the second season and developed the thickest stems, measuring 0.60 centimeters in diameter. They also produced the most leaves, with an average of 196 leaves per seedling in the second season, and their leaves were larger, heavier, and contained more green chlorophyll than any other group. While the iron treatments also helped the plants grow taller and produce more leaves compared to the water-only group, the magnesium treatment consistently outperformed the iron in terms of overall size and leaf production.

Beyond just getting bigger, the plants showed a deeper internal change. The seedlings treated with the highest dose of magnesium accumulated the most carbohydrates, which are the sugars and energy reserves the plant builds to support its structure. This group reached a carbohydrate content of roughly 3.75 percent in their leaves. The iron treatment, however, had a different specialty. The seedlings sprayed with 30 milligrams per liter of chelated iron ended up with the highest levels of nitrogen and iron within their leaves. Nitrogen is a key building block for proteins, and having more of it helps the plant build its tissues. The magnesium treatment also helped the plants absorb other important minerals like potassium, phosphorus, and zinc more effectively. The researchers found that the magnesium not only helped the plant grow but also acted like a key, unlocking the plant's ability to take in and use other nutrients from the air and soil.

The study concludes that for nursery owners looking to produce strong, healthy peach rootstock quickly, the most effective strategy is to spray the leaves with magnesium sulphate at 3 grams per liter and chelated iron at 30 milligrams per liter. This combination creates a powerful synergy, where the magnesium drives rapid physical growth and energy storage, while the iron ensures the plant has the necessary tools to build proteins and transport energy. By following this schedule of three sprays starting in mid-June, growers can produce vigorous seedlings that are ready for grafting in a shorter time than usual. The research suggests that this approach does not just make the plants bigger; it fundamentally improves their nutritional status, ensuring they are robust enough to support the future fruit-bearing tree. While the researchers noted that higher concentrations might be tested in the future, the current levels proved to be the most efficient method for achieving superior seedling vigor under these specific conditions.