Maize is a very special crop. Due to its tropical origin and its different carbon assimilation cycle (C4), it requires an adequate amount of heat and light practically throughout the growing season. As a result of appropriate selection and subsequent breeding, cultivars adapted to temperate or even cooler climatic zones have been developed, but it still remains a plant with relatively high thermal and light requirements. Therefore, apart from the obvious necessity to choose the right varieties, a very important element leading to a high yield is the maximum use of the potential of a given site, as well as the appropriate prevention of consequences resulting from unpredictable weather conditions.
The date for sowing maize in Poland, depending on the region and the weather, is between 15 April and 10 May, which means that, in Poland’s climatic conditions, it can coincide with the occurrence of unfavourable conditions. Sometimes in the initial period of its growth it may be cool and humid, and sometimes, on the contrary, soil drought occurs. Especially for dent-type varieties, sowing should begin when the soil has warmed up to 8-9OC at a depth of 5-10 cm. For flint varieties, a temperature of 5-6OC is sufficient and their cultivation is possible on heavier sites in cooler conditions with a delayed spring. Warm weather guarantees fast and even emergence, provided there is sufficient moisture in the soil. Seeds sown into warm soil germinate quickly, which minimises the occurrence of seedling diseases. In too cool a soil, the seeds swell, but often do not form a root or germ. This can even lead to their death. Maize is also very sensitive to frosts before emergence. Under these conditions, damage to the sprout tips sometimes occurs. This causes the leaves to develop below the surface of the soil and then makes emergence difficult or even impossible. The germination process of maize seeds is a “hormonal storm”, which starts with the absorption of water in 3 basic phases.
Phase 1 – Rapid water absorption – occurs due to the pressure difference between the seed and the surrounding environment,
Phase 2 – Temporary interruption of water absorption due to the use of spare substances (carbohydrates, proteins, etc.) to produce new compounds necessary for the germination process,
Phase 3 – Resumption of rapid water uptake due to production of low molecular weight compounds.
The rapid absorption of water in phases 1 and 3 destroys the structure of cell membranes and thus causes stress the more unfavourable the environmental conditions are at that time. All phases of germination are regulated by hormones such as abscisic acid, cytokinins and gibberellins. Since it is impossible to predict with certainty under which conditions maize sowing will take place, the risk of unfavourable conditions is virtually always present. Although it cannot be completely eliminated, in many cases the adverse consequences can be minimised. One such possibility is the use of the microbial seed dressing SuperPower. The seed dressing consists of a mixture of many species of bacteria from the group (PGPR – Plant Growth Promoting Rhizobacteria), which stimulate the correct functioning of hormones related to the germination process and affect the better development of the root system. These bacteria have the ability to reduce the production of so-called stress ethylene, which is an undesirable aging hormone that occurs as a result of stress. In addition, the bacteria applied to the seed during dressing have the ability to produce siderophores – natural compounds that chelate metals, especially iron. Siderophores convert mineral substances into simple organic compounds, such as amino acids, which are the building blocks of tissues. In addition, the presence of siderophores near the roots of plants can protect them from many pathogens by binding into chelates all available forms of iron and not making it available to pathogenic organisms. The use of SuperPower fertiliser results in better and more even emergence, stimulates seedling growth and increases the efficiency of nutrient uptake. This is confirmed by research conducted at the Institute of Soil Science and Plant Cultivation National Research Institute in Puławy, where the application of SuperPower resulted in an increase in maize aboveground weight by 8.9%, as well as an increase in root mass by 15.2%. The dressing is applied in the amount of 1 kg per 1 ton of maize grain. The required amount of the preparation should be dissolved in a small amount of water (approx. 0.5 l) by vigorous shaking, and the resulting solution should be added to the dressing, mixed and dressed as usual.