Nanofertilizers are increasingly explored for sustainable micronutrient delivery in agriculture. Pre-treating seeds with nanofertilizers prior to planting (i.e., seed priming) reduces concerns about nanoparticle (NP) fertilizer non-target dispersion; however, priming formulations and concentrations must be carefully selected to avoid germination inhibition and toxicity. Here we investigate changes in corn seed germination and seedling development after seed priming with ZnO NPs, ZnO bulk and ZnCl₂. To evaluate the effects sterile seeds were immersed in priming solutions of 0, 20, 40, 80, 160 mg L⁻¹ Zn for the three Zn sources. Following an 8 h priming the seeds were evaluated for germination and vigor for 5 days on germination paper. Root and shoot lengths were measured as well as fresh and dry biomass. Compared to the control, the ZnO NP and ZnCl₂ seed priming promoted beneficial effects. ZnO NP seed-priming exhibited a concentration dependent profile in improving seedling growth, with greatest benefit around 80 mg L⁻¹, providing 17%, 25% and 12% higher values than control for germination, root length, and dry biomass production, respectively. In contrast, seeds primed with bulk ZnO did not differ from the control. These findings support NP-seed priming as an alternative to delivery of essential micronutrients, such as zinc, to corn seedlings.

From 1913 onwards, the global situation changed from a scenario of nitrogen (N) scarcity to an abundance of ammonia (NH ₃ ) produced synthetically via the Haber-Bosch process. Several N compounds have been synthesized since then, with urea becoming the main source of N, accounting for 55 % of current N consumption. However, N efficiency in agroecosystems is low and, normally, N recovery in cultivated plants is less than 50 %. This occurs because a large amount of reactive N is lost to the environment, inducing various forms of pollution, threatening human and environmental health, in addition to causing a negative economic impact on the farmer. The main processes responsible for low N efficiency are NH ₃ volatilization, leaching, and N denitrification. Considering global NH ₃ volatilization losses of 14 %, it can be assumed that up to 8.6 million Mg of urea are lost every year in the form of NH ₃ . For each ton of NH ₃ produced, 1.9 to 3.8 Mg of CO ₂ is emitted into the atmosphere. Therefore, increasing N use efficiency (NUE) without compromising yield is a necessity and a challenge for crop improvement programs and current management systems, in addition to reducing greenhouse gas emissions. In this context, enhanced efficiency fertilizers (EEFs), which contain technologies that minimize the potential for nutrient losses compared to conventional sources, are an alternative to increasing the efficiency of nitrogen fertilization. Currently, EEFs are classified into three categories: stabilized, slow-release, and controlled-release. This study aims to understand the technologies used to produce EEFs and the factors that govern their availability to plants. This review covers the following topics: the discovery of N, N dynamics in the soil-atmosphere system, N assimilation in plants, strategies to increase NUE in agrosystems, NH ₃ synthesis, NH ₃ volatilization losses, N fertilizer technologies, the importance of characterization of EEFs, conventional nitrate or ammonium-based fertilizers to reduce gaseous losses of NH ₃ and future prospects for the use of N fertilizers in agriculture.

A compreensão e a quantificação do impacto dos sistemas de uso e manejo nos teores de C orgânico do solo (COS) e em propriedades físicas são fundamentais para o desenvolvimento de sistemas agrícolas sustentáveis. O objetivo deste trabalho foi avaliar alterações em alguns atributos físicos e COS de um Latossolo Vermelho da região noroeste do Paraná sob diferentes sistemas de uso e manejo: mata nativa, pastagem e as culturas de mandioca e de cana-de-açúcar. Foram coletadas amostras deformadas para determinação da textura, da densidade de partículas, do ensaio de Proctor normal e dos teores de matéria orgânica; e amostras indeformadas, para determinação da densidade do solo (Ds) e porosidade do solo. Os resultados indicaram que os sistemas de manejo estudados induziram alterações nos atributos físicos do solo em relação à mata nativa, o que foi verificado pelos maiores valores de Ds, densidade relativa do solo e densidade máxima do solo e menores valores de macroposidade, porosidade total, COS e estoque de C do solo, na seguinte ordem crescente: pastagem, mandioca e cana-de-açúcar. Contudo, as áreas não são consideradas fisicamente degradadas. Os valores de densidade máxima do solo foram de 1,91, 1,93, 2,00 e 2,03 Mg m-3, e os de estoque de C do solo, de 17,8, 16,6, 12,8 e 12,1 Mg ha-1, para mata nativa, pastagem, mandioca e cana-de-açúcar, respectivamente.

Aluminum (Al) toxicity is one of the most limiting factors for productivity. This research was carried out to assess the influence of Al nutrient solution on plant height, dry weight and morphoanatomical alterations in corn (Zea mays L.) roots and leaves. The experiment was conducted in a greenhouse with five treatments consisting of Al doses (0, 25, 75, 150, and 300 µmol L-1) and six replications. The solutions were constantly aerated, and the pH was initially adjusted to 4.3. The shoot dry matter, root dry matter and plant height decreased significantly with increasing Al concentrations. Compared to the control plants, it was observed that the root growth of corn plants in Al solutions was inhibited, there were fewer lateral roots and the development of the root system reduced. The leaf anatomy of plants grown in solutions containing 75 and 300 µmol L-1 Al differed in few aspects from the control plants. The leaf sheaths of the plants exposed to Al had a uniseriate epidermis coated with a thin cuticle layer, and the cells of both the epidermis and the cortex were less developed. In the vascular bundle, the metaxylem and protoxylem had no secondary walls, and the diameter of both was much smaller than of the control plants.

The development of new fertilizer technologies to reduce nitrogen (N) losses from an agricultural system and to increase nitrogen use efficiency (NUE) is a global research objective. Controlled-release nitrogen fertilizers have shown great potential for reducing N losses and synchronizing N release according to crop demand, thereby improving the NUE. The objective of this study was to characterize controlled-release nitrogen fertilizers and compare them with conventional nitrogen sources in terms of N release, N loss via NH3 volatilization, and [...] ABSTRACT The development of new fertilizer technologies to reduce nitrogen (N) losses from an agricultural system and to increase nitrogen use efficiency (NUE) is a global research objective. Controlled-release nitrogen fertilizers have shown great potential for reducing N losses and synchronizing N release according to crop demand, thereby improving the NUE. The objective of this study was to characterize controlled-release nitrogen fertilizers and compare them with conventional nitrogen sources in terms of N release, N loss via NH3 volatilization, and