Péter Csontos

The effects of the rust fungus Puccinia komarovii Tranzschel and the aphid Impatientinum asiaticum Nevsky 1929 on plant height, seed number per capsule, and seed mass were investigated in eight small balsam (Impatiens parviflora DC.) stands in Hungary and one in Poland. Two stands were infected by rust, five by aphids, and two were healthy. The lowest average plant height was 37.5 cm and the highest 94.7 cm, both measured in aphid-infested stands. Examining the stands separately, no relationship appeared with the type of damage. For data pooled across stands, differences were significant: rust-infected plants were the tallest, healthy shoots were the shortest, while aphid-infected plants fell in between. Mean seed number per capsule was the lowest (1.53) in the pest-free Nagybörzsöny stand, and the highest (2.33) in the aphid-infested Bielsko-Biała stand. In pairwise comparison of stands, average seed number did not differ in most cases. Significant positive correlation was found between average plant height and average seed number per capsule. Seeds were the heaviest in the healthy stand, whereas they were lighter in rust-infected and aphid-damaged stands. Regarding the applicability of the studied pests as biological control agents, the results showed that both pests reduce seed mass but not overall performance of the host plant.

N fertilisation affects the nutrient content of grasslands, and thus animal health. The effect of fertiliser treatments with calcium ammonium nitrate at doses of 0, 100, 200 and 300 kg N ha⁻¹ year⁻¹ was investigated on grassland nutrient content in a long-term field experiment. The dilution effect due to biomass growth was analysed separately from other effects. The biomass of the grass increased 3.4-fold, up to 5.82 t ha⁻¹. N fertilisation significantly reduced the concentrations of P and Mo and increased the concentrations of N, NO₃–N, Na, Mn, and Cu in the grass. From a grazing or feeding perspective, N treatment adversely increased the NO₃–N concentration, which exceeded the risky level of 1500 mg NO₃–N kg in the 200 kg N ha year⁻¹ treatment and decreased the P concentration. The treatments favourably increased the Na, Cu and Zn concentrations, reduced the Mo concentration, and improved the tetany index and the K:Na ratio. The 100 kg ha⁻¹ year⁻¹ N dose can be recommended under conditions similar to those in the experiment. It is important to analyse the element content of grass when using mineral fertiliser in order to minimise animal health risks.

The effects of the rust fungus Puccinia komarovii Tranzschel and the aphid Impatientinum asiaticum Nevsky 1929 on plant height, seed number per capsule, and seed mass were investigated in eight small balsam (Impatiens parviflora DC.) stands in Hungary and one in Poland. Two stands were infected by rust, five by aphids, and two were healthy. The lowest average plant height was 37.5 cm, the highest 94.7 cm, both measured in aphid-infested stands. Examining the stands separately, no relationship appeared with the type of damage. For data pooled across stands, differences were significant: rust-infected plants were the tallest, healthy shoots were the shortest, while aphid-infected plants fell in between. Mean seed number per capsule was the lowest (1.53) in the pest-free Nagybörzsöny stand, and the highest (2.33) in the aphid-infested Bielsko-Biała stand. In pairwise comparison of stands, average seed number did not differ in most cases. Significant positive correlation was found between average plant height and average seed number per capsule. Seeds were the heaviest in the healthy stand, whereas they were lighter in rust-infected and aphid-damaged stands. The pests tested had no detrimental effect on Impatiens parviflora, but both pest types somewhat reduced the seed mass. The applicability of the studied pests as biological control agents against host plant invasion is also discussed.

Nitrogen (N) fertilisers should be utilised as efficiently as possible. In addition to N fertiliser doses, nitrogen use efficiency (NUE) is influenced by other factors. The effects of four different N, phosphorus (P), and potassium (K) supply levels (0–3) and rainfall periods (dry, normal, wet) were investigated on NUE indices in six selected years of a field experiment. Generally, rainfall and N had the strongest effects. N × rainfall supply interaction increased biomass production from 0.915 t ha⁻¹ (N0, dry) to 10.4 t ha⁻¹ (N3, wet). The N balance varied between −47.3 kg ha⁻¹ (N0, wet) and 218 kg ha⁻¹ (N3, dry). The N uptake per unit N of fertiliser (FNRE) was mainly determined by the P × rainfall interaction, varying between 26.13% (P0, dry) and 83.73% (P3, wet). Both the biomass increment per unit N of fertiliser (agronomic efficiency—AE) and the biomass production per unit N uptake (internal efficiency—IE) were mainly influenced by the N × rainfall interaction, with AE decreasing from 43.7 kg kg⁻¹ (N1, wet) to 10.6 kg kg⁻¹ (N3, dry) and IE from 114 kg kg⁻¹ (N0, normal) to 45.9 kg kg⁻¹ (N3, wet). Both P and, to a lesser extent, K had a significant positive effect on these indices. The N dose of 200 kg ha⁻¹ year⁻¹, the P₂O₅ supply of 153 mg kg⁻¹, and the K₂O supply of 279 mg kg⁻¹ proved to be optimal in terms of NUE indices.

This research is part of a Hungarian Research OTKA project that examines the vegetation of sandy grasslands along the Danube. During this study, Festuca wagneri and Festuca tomanii were identified as potentially suitable grass species for urban planting and turf establishment based on preliminary research. Our aim was to determine the germination success of seeds from aesthetically selected individuals and to identify the growing media on which they germinate most effectively. From the collected Festuca individuals, we analyzed 30 specimens of each taxon under garden conditions and selected the individuals for germination. The Festuca tomanii individuals were uniform, so we selected only 5 individuals. The Festuca wagneri individuals were categorized into three groups: leaves and inflorescence densely upright, inflorescence shoots spread out, and low ’dwarf’ form (compact and dense but short in stature). It was assumed that Festuca species seeds would germinate better in sandy soils. To test our hypothesis, seeds from ten Festuca wagneri and five Festuca tomanii individuals, selected based on aesthetic criteria, were sown in six different substrates: a sand–peat mixture, sand, coconut fiber, peat, coconut fiber–sand mixture, and native sandy soil (Calcaric Arenosol). Contrary to our expectations, the growth and germination rates of seeds sown in peat and coconut fiber substrates were higher than those in native sandy soil. These results suggest that Festuca seeds germinate better on substrates resembling dead plant debris with a peat-like structure or on the surface of live mosses rather than on bare sand. Among the examined individuals, the seeds from the spreading Festuca wagneri group exhibited the highest germination rate, making this group particularly suitable for urban environments. Additionally, one of the upright Festuca wagneri individuals showed the highest leaf average length and should also be considered for urban planting. In contrast, despite their uniform appearance, the Festuca tomanii individuals did not demonstrate similar germination trends. In fact, the seeds from two clumps did not germinate at all, indicating that further research is necessary.

Water shortage, one of the main limiting factors for plant growth and development, can be alleviated by an adequate nutrient supply. The effect of different nitrogen (N), phosphorus (P) and potassium (K) supply levels and their combinations was examined in different rainfall supply periods (wet, normal, dry) on a grass sward in a field experiment. Dry and fresh aboveground biomass production were primarily increased by the N–rainfall supply interaction, from 0.739 to 6.51 and from 1.84 to 21.8 t ha⁻¹, respectively, but the P–rainfall supply and N–P interactions and K treatment all had significant effects. Dry matter content was primarily influenced by the N–rainfall supply interaction, increasing in response to N in dry periods and declining in wet periods. Water use efficiency (WUE) was increased by the N–rainfall supply interaction from 28.3 to 127 kg ha⁻¹ mm⁻¹, but the N–P interaction had a similarly strong effect, and K treatment increased it in the dry period. The N, P and K contents of the aboveground biomass were increased by treatment with the corresponding element, but were also influenced by rainfall supply. The increase in biomass, mainly due to N treatment, caused the dilution of the P and K contents in grass in treatments poorly supplied with P and K. Biomass production and WUE were significantly improved up to a dose of 200 kg ha⁻¹ year⁻¹ of N, up to a supply level of 153 mg kg⁻¹ of P₂O₅, and 279 mg kg⁻¹ of K₂O measured in the soil. Treating grass with the N, P and K macroelements may effectively increase biomass production and water use efficiency, but above a certain level their application is unnecessary.