Micronutrient Knowledge Base

Although the nanoparticle (NP) utilization in agronomy is currently orientated to intensify crop yield, the potential negative effects on soil and plant reproductive organs, including effects on pollen are largely absent in the literature. For this reason, our study was set to evaluate the impact of ZnO nanoparticles (ZnO-NPs) on the selective properties of Fluvisol, on the direct microbial activity and zinc (Zn) phytoavailability, and crop yield after their foliar application on soybean [Glycine max (L.) Merril] under field conditions. Additionally, the potential hazardous impact to plant reproductive structures was evaluated, focusing on the agronomically and environmentally sensitive biomarker – pollen viability. The soil biological activity was evaluated through microbial respiration while Zn phytoavailability was determined using reaction agents with nutrients analysis conducted through fl ame atomic absorption spectroscopy (F-AAS). Pollen viability was evaluated using the iodine potassium iodide (IPI) test. The experiments were carried out at an experimental site of the Faculty of Agrobiology and Food Resources (FAFR) at the Slovak University of Agriculture (SUA) in Nitra, located in Central Europe, during the 2023 vegetation season. Depending on increasing concentrations of ZnO-NPs through order of 1.4, 14, and 140 mg∙L–1, revealed no harmful effect on soil microbial activity or hazardous Zn accumulation in the context of its Fluvisol-phytoavailable distribution compared to NPs-free control. A positive impact on soybean pollen viability was observed at all applied ZnO-NP concentrations compared to the NP-free control. The highest pollen viability, reaching up to 97.04%, was achieved at a concentration of 1.4 mg∙L–1, and, subsequently, it slightly decreased with increasing concentrations of ZnO-NPs. Moreover, the application of ZnO-NPs had a positive impact on soybean weight of thousand seeds and seed yield, where it’s the highest concentration was the most effective. Thus, our results directly demonstrate the positive effi ciency on selective properties of soil and reproductive structure – pollen, where ZnO-NP spray application acted positively and stimulatingly. Additionally, ZnO-NPs had positive impact on weight of thousand seeds (TSW) and seed yield. Therefore, the use of nanoparticles in foliar applications could be considered as kind of novelty in precision and sustainable agriculture.

In well-pH-balanced soils, micronutrient deficiencies in crops are usually rare in our clay soils, but there are some exceptions. Our soils are naturally high in calcium, iron, and magnesium, while the micronutrients of copper, nickel, and molybdenum are needed in such small quantities that deficiencies are unlikely in most soils. Deficiencies in these nutrients in our clay and silt-based soils are normally caused by high or low pH, which makes them unavailable. The nutrients of boron, manganese, chloride, and zinc are a little different, though. There are some places where these nutrients don’t have a naturally high background level, but they aren’t always a concern either. All of the micronutrients have different aspects, reactions, and levels of concern in the soil. (Technically, calcium and magnesium are secondary nutrients, but they are close enough for this discussion.)

Corn production in Georgia declined in 2022 following 4 years of continual increases between 2018 and 2021. The planted acreage of corn in Georgia decreased by 11.5% in 2022 compared to 2021 but is still greater than 2019, a pre-COVID19 pandemic year. The harvested acreage also decreased by 13.5% in 2022 compared to 2021. Likewise, grain yield increased by 4% in 2022 compared to 2021. Corn planted and harvested acreage, as well as grain yield, over the past 10 years in Georgia is shown in Table 1. Corn is a vital crop in row crop rotations in Georgia, ensuring the diversity and stability of farm income. Corn remains the third-largest row crop, after cotton and peanut, and according to the 2023 Georgia AgSnapshots report, corn's economic value was $509.1 million, the eighth agricultural commodity by economic value in Georgia. Georgia corn is also vital to the state’s livestock and ethanol industries. On average, Georgia farmers produce more than 60 million bushels per year. The majority of Georgia corn production is dent corn or field corn and agronomic production practices vary by region. Across the state, most of the corn is grown on 30 to 36-inch row spacings with some growers going as wide as 40 inches and others going as narrow as 15 inches. In the Coastal Plain region, tillage systems are predominately conventional or strip-till, whereas the Piedmont and Mountain regions are predominately strip-till or no-till. Furthermore, in the Coastal Plain approximately 90% of the corn is irrigated, compared to approximately 50% and 10% for the Piedmont and Mountain regions, respectively. Irrigation is crucial in the Coastal Plain, where sandy soils with low water holding capacity dominate, to achieve high-yielding corn. Soils with greater water holding capacities and shallow water tables in river bottoms help offset the effects of drought in the Piedmont and Mountain regions. Across all these different production systems, Georgia corn growers have demonstrated the ability to achieve great corn grain yields in the past. These yields have been achieved through the adoption of modern corn hybrids coupled with improved management technologies and careful attention paid to all production practices. In 2022, multiple growers in Georgia had yields of 300+ bushels in irrigated production systems. While many of these yields were achieved with great help from favorable environmental conditions, they were still a product of great management systems. As you strive to increase your corn yields, the key is to carefully consider and track all your management decisions and practices throughout the growing season. Detailed field notes are not only a good way to understand what you did right during the growing season, but more importantly, to know what went wrong. Knowing what went wrong during one growing season will help prevent the same missteps in the following years. The following chapters contain information gathered from years of research in Georgia and will hopefully help you in making the best crop possible with maximum returns from your 2022 corn crop.

Abiotic factors, such as drought, can significantly impact the vegetative growth and productivity of maize. To investigate the effects of the combined foliar application of zinc (Zn) and iron (Fe) nanoparticles with the recommended nitrogen dose (RND) on maize production and grain chemical composition under different water regimes, two field experiments were conducted in El-Ayyat city, Giza, Egypt, during the summer seasons of 2022 and 2023. This study utilized a split-split-plot experimental design with three replications. The main plots were designated to different water regimes (100, 80, 60, and 40% of estimated evapotranspiration), while the sub-plots were randomly distributed with Zn and Fe nanoparticle concentrations (0, 100, and 200 mg/L). The sub-sub-plots were randomly allocated to three maize cultivars (SC-P3062, SC-32D99, and SC-P3433). The results revealed that exposure to drought conditions resulted in a significant decline in the yield and yield-related attributes across all maize cultivars examined. Grain yield decreased by 10–50% under drought conditions. However, the foliar application of Zn and Fe nanoparticles was found to significantly improve grain yield, protein content, oil content, starch content, crude fiber, ash, and macro- and micronutrient concentrations in the maize cultivars under control and drought stress conditions. The foliar application of Zn and Fe nanoparticles at a concentration of 200 mg/L to the SC-P3433 maize cultivar led to the greatest grain yield per hectare, reaching 11,749 and 11,657 kg under the irrigation regimes with 100 and 80% total evapotranspiration, respectively. According to the assessment using the relative drought index, the SC-P3062 maize cultivar demonstrated tolerance (T) to water stress conditions. In conclusion, the foliar application of Zn and Fe nanoparticles (100–200 mg/L) effectively mitigated the negative effects of drought stress on maize plants. This approach can be recommended for farmers in arid and semi-arid regions to maintain and improve maize yield and grain quality under water-deficit conditions. Keywords: corn; water regime; yield; protein; starch; macro- and micronutrients

Biological nitrogen fixation in soybean is enhanced when seed is treated with cobalt (Co) and molybdenum (Mo) prior to planting. In this study, our objective was to verify if Co and Mo application during the reproductive phase of the crop increases seed Co and Mo concentration without adverse effects on seed quality. Two experiments were conducted. First, we investigated foliar and soil Co and Mo application under greenhouse conditions. Next, we validated the results obtained in the first study. The treatments for both experiments consisted of Co doses combined with Mo, and a control without Co and Mo application. The foliar application was more efficient in producing enriched Co and Mo seed; meanwhile, as Co doses increased so did Co and Mo concentrations in the seed. There were no adverse effects on nutrition, development, quality, and yield of parent plants and seed when these micronutrients were applied. The seed showed higher germination, vigor, and uniformity for the development of soybean seedlings. We concluded that the application of 20 g ha􀀀1 Co and 800 g ha􀀀1 Mo via foliar application at the reproductive stage of soybean increased germination rate and achieved the best growth and vigor index of enriched seed. Keywords: germination; Glycine max; plant nutrition; seed quality; Cerrado