Hoorman: Seed Quality Effects Germination
As spring planting gets underway, farm stress is high. When seeds germinate quickly that farm stress goes away. Getting new seeds and plants off to a vigorous start increases the potential for a healthy crop with abundant yields. However, when seeds germinate slowly because of challenging soil or weather conditions, early stress on young seedlings is likely to produce a yield drag.
When seeds germinate quickly, corn seed maggot feeding decreases. When root systems develop quickly, wireworm or rootworm larvae is greatly reduced. When seedlings grow very rapidly, and have balanced seed nutrition, they can resistant slugs and flea beetles feeding. However, none of these positive effects occur when seeds germinate slowly or when seeds are of poor quality.
Planting conditions are not always ideal. Poor weather conditions means that often planting occurs under less-than-ideal conditions. Farmers typically have only about 9-10 days or less to get most crops planted on time. It is even probable that weather and soil conditions will be less than ideal more frequently in the future. Weather variability this year may even impact germination next year by producing poor quality seed.
When farmers purchase seed, the quality may not always be the best. Many seeds may germinate but lack vigor, and may germinate slowly, even when planted in ideal conditions. This is especially true of commodity grain crop seeds, but also for many vegetable seeds. A researcher tested several hundred seed corn samples from seed suppliers and planted them in seedling trays to test germination and seed vigor. While most of the seed samples reached the germination percentage on the label, many germinated quite slowly, emerging only 5-7 days after being planted. Some emerged 10 days after being planted, despite being maintained in perfect moisture and temperature conditions for rapid germination.
In seed corn production, small seed size seems to be ideal. Hybrid seed corn has a lower yield and often plant nutrition is adjusted for lower yields. Before pollination, the plants are “detasseled” by cutting off the plant above the ear, which removes up to 50% of the plant’s photosynthetic capacity. To keep seed size small, plants are desiccated as soon as the seeds reach maturity. The corn seed is smaller, lower in stored carbohydrate energy, and may have less mineral nutrition; resulting in lower quality seed, especially if weather conditions were poor. Seeds with lower nutrition may germinate slowly and are particularly susceptible to insects and disease. Seeds with high seed vigor and good nutrition generally germinate the fastest and get that crop off to a fast start.
The best fast germinating seeds contains abundant nutrition, mineral nutrition as well as carbohydrates, proteins and fats. Seed with generous nutrition will be heavy, have fewer seeds per pound, and have a high-test weight. In addition, the best seed also carries a population of beneficial microbes on the seed surface that immediately colonizes emerging roots and leaves. The inherited microbes from the parent seed are very important. Over time, over using harsh chemicals on your seed may reduce the viability of these beneficial microbes that help a plant get off to a fast start.
Fast root microbial colonization helps reduce root diseases. Without beneficial microbes on the seed, new seedling now need to recruit beneficial soil microbes. This process takes time (up to two weeks) and more energy. Diseases like fusarium, rhizoctonia, pythium, anthracnose, phytophthora and many other root-rot diseases may take over when disease repressing microbes are not present. Seeds that do not carry healthy microbes predispose young seedlings to disease susceptibility. Fungicide seed treatments may even make this process worse.
Some of these beneficial microbes are called plant growth promoting rhizobacteria or PGPR’s. These bacteria produce phytohormones that influence plant growth and development, particularly root branching. Robust root systems, established immediately after germination, are a critical to producing large crop yields. PGPR’s also increase stem size and create a larger vascular system to increase plant nutrition. Plants have the genes to produce more grain and fruit, but often the pipeline is not large enough to supply the water and nutritional requirements to support higher yields
Seeds with abundant trace minerals (manganese, zinc, copper and boron) germinate quicker than those without. Some farmers apply a combination of chelated trace minerals (25 to 100 ounces each) of manganese, iron, zinc, cobalt and copper per ton of seed. When selecting seed, look for high test-weights and healthy seed to increase crop yields. Adding the right biologicals (inoculants) that contain beneficial microbes may be helpful if they are missing in your seed. Overall, seed health and plant health are important for producing high quality food and higher yields.