Éva Lehoczky

Loss of Nutrients Caused by Excessive Weediness at the Early Stage of Maize Vegetation Period

Abstract The experiment was carried out in a field previously not exposed to herbicides, in which jimsonweed (Datura stramonium L.) and wild hemp (Cannabis sativa spp. spontanea) were the dominant weeds. Using sites identified with global positioning system (GPS) coordinates, changes in abundance of weeds in time were investigated. Before the trial in autumn, soil samples were taken for analysis. Nutrient uptake was determined and compared with the results of the spring plant examinations. One month after the sowing of maize (Zea mays L.), the total number of weeds and the number of weed species present at the sampling sites were determined, and aerial fresh and dry weights of the crop and weed plants were measured. Plant tissue samples were assayed for contents of nitrogen, phosphorus, potassium, and calcium, and data obtained from weedy and weed‐free control areas were compared. Similarly, maize yields were determined, and their dependence on plot weediness was evaluated. We found that uptake of large amounts of nutrients by jimsonweed and wild hemp at the early stage of the development of maize is an important factor in crop‐weed competition.

Study on competition between maize and weeds in long-term soil tillage experiments

One of the biggest challenges for the safe maize production is the yield stability in a wide range of environments with different soil fertility, weather conditions, prevailing pests and diseases as well as cultural practices. In order to achieve it, new hybrids with higher tolerance to biotic and abiotic stress are continuously being created. In order to compare performance of maize hybrids in environments with different levels and types of stress, and relate it to the stalk lodging incidence, we compared performance of 64 maize hybrids obtained by crossing 16 inbred lines with four inbred testers in three different environments. Two environments at same location (Rugvica) differed in crop rotation, and the third environment at location Botinec was considered as dry because of low water capacity of the soil. Mixed models that included all design elements and genetic background of hybrids were used to analyze the effect of lodging on yield in different environments. The results show that stalk lodging had a significant effect on yield, but significant lodging x environment interaction indicates that this effect was rather environment specific.Sweet pepper Istra F1 hybrid was grown in a greenhouse on K rich soil. For evaluation of K antagonism, two K rates (55 and 85 kg ha-1) were applied in a randomized complete block design with four replications. Total number of fruits, total number of BER affected fruits as well as average fruit mass were recorded for each harvest. Fruit and leaf K and Ca content were determined at three plant growth stages (at the stage of the first, third and fifth fruit cluster). Higher K rate gave higher : average fruit mass (169.45 g), total number of fruits per plant (7.95), number of BER affected fruits per plant (3.82), K in leaves (5.44% DM), K in fruits (6.35% DM), but negatively correlated with Ca concentration in fruits (0.57% DM) and leaves (3.24% DM). This resulted in decreased marketable yield of sweet pepper fruits.

EFFECT OF THE SOIL TILLAGE AND N-FERTILIZATION ON THE WEEDINESS OF MAIZE

Introduction The valuation of cultivation systems and comparison takes important place in the research of plant production. The soil cultivation influences basically the soil as natural source of energy, the productivity of agriculture and the economic of production. (Kismanyoky et al. 1997, Birkas et al. 1999, Toth 2003). The methods and tools of soil cultivation dispose to weed control effect, as follows the ploughing, disc tillaging, harrowing, cultivating. Aspect from the weed control, the stubble stripping is the most important crop establishment work. Which aim is to eliminate the weeds on the stubble and the seeds in the soil, and to constrain to sprout the weed seeds (Ujvarosi 1973). In the last decades in the agrotechnical changing and the increasing of fertilizers usage was very important and the amount of fertilizers multiplied. After that yield increased, the fertilizer multiplication influenced the composition of weed population. The level of manuring probably has an effect on the combination of weeds, because of the different competitive capacity of weeds and they reactions. The professional manuring produce results powerful crop plant cover and less weediness (Kadar et al. 1999). There are essential differences in the cover of weeds and in the number of the weed species depending on the fertilization system employed (Lehoczky Kismanyoky 2005). Nitrogen fertilization often cannot increase the competitive ability of crops to weeds. It may even reduce it depending on the weed species (Lehoczky 2003). Fertilizer application cause a greater increase in the phosphorus uptake of weeds than that of maize, as weeds utilized fertilizer phosphorus more efficiently than maize (Lehoczky et al. 2006). On the cultivated fields the influence of weeds shows wide diversity. The common of weeds, control a many factor, which in seems the most important influential factor the agrotechnical as anthropogenic element. In the last decades, the disc tillage and the no-till drill cultivation methods have come to the forefront. In Hungary, the opinion about direct drilling is differing. It is fact, that the weediness is one of the derogatory factors of the direct drilling (Birkas et al. 1999). The aim our study was to investigate the effect of the cultivation methods to the weediness and the number of weeds. The experimental investigate was made in maize on 5 of June 2006. The effect of the different cultivation methods demonstrated markedly the weed cover on the plots and the number of weed species.

Investigation of the Damage Caused by Weeds Competing with Maize for Nutrients

The experiment was set up on a trial site where the weed infestation was already known. The objective of this study was to achieve efficient weed control. The effect of herbicide treatments on biomass production and nutrient uptake of weeds were determined and the impact on corn yield was measured. Effect of the maize–weed competition on the biomass and yield production of maize was tested in 2005 at Keszthely, Hungary. A randomized small plot trial was carried out in three replications on Eutric cambisol soil. The effect of the herbicide treatment was compared to the untreated plot. The tested herbicide was Trophy at 3 l fp ha−1 (active ingredient [a.i.] acetochlor + dichlormid) in a tank mix combination with Merlin at 0.12 kg fp ha−1 (a.i. isoxaflutole), which provided excellent weed control. The products efficacy was evaluated by estimating the percentage of weed cover in 1 m2. Individual weed species were identified, and the efficacy was evaluated by species. The fresh and dry weights of weeds and maize were measured, along with the effect of the weeds on the growth of maize and on the yield. The percentage of weed coverage in the untreated plot was 9.6% at the first (3 June) and 28% at the second (4 July) evaluation. The weed coverage in the treated plot was 0.5% at the first and 0.6% at the second evaluation. The fresh and dry shoot weights were measured on 27 July, and both the fresh and dry weights of the crop were reduced by 25 and 55%, respectively, in the untreated plots in comparison to the treated ones. The fresh and dry weights of cobs were reduced by 47% and 56% in the untreated plots. The herbicide treatment provided good weed control and provided favorable conditions for the crop. As a consequence, the fresh and dry weights of maize were 1.9 and 2.3 times higher in the treated plots than in the untreated ones. Nutrient concentration of maize was measured as well, to estimate the proportion of nutrient uptake by different plant species and the competition for nutrients between maize and weeds. The effect of the competition of weeds was that there were 1.9–2.3 times fewer corncobs on the control plots. There was strong competition between weeds and corn for nutrients. On the weedy control plots, weeds contained 16 kg ha−1 nitrogen (N), 2.5 kg ha−1 phosphorus (P), and 28.2 kg ha−1 potassium (K), whereas corn contained 38.2 kg ha−1 N, 4.2 kg ha−1 P, and 29.5 kg ha−1 K.

Weediness and nutrient uptake by weeds in relation to the soil tillage.

The study was carried out in 2006 in Keszthely, on the soil tillage portion of a long‐term experiment. In this experiment, a combination of three cultivation methods [no‐till drill, disk tillage, conventional tillage (plowed)] and five nitrogen (N) rates (N0: 0, N1: 120, N2:180, N3: 240, and N4: 300 kg N ha−1) were assessed. The trial was arranged in a split‐plot design with four replications, and it was carried out during the first occurrence of maize in winter wheat–winter wheat–maize–maize rotation. Maize was sown on 10 May 2006; the weed survey was carried out using Balázs‐Ujvárosi coenological method on 5 June 2006, after which weed control was implemented. Maize biomass of plants at the three to four leaf stage was determined at the same time. Sixteen weed species were identified in the no‐till treatment, and 14 each in the in the conventional and the disk tillage treatments. Cultivation systems had a profound effect on the weediness of maize, with the lowest weediness occurring in the conventional tillage treatment. There was a strong interaction between N application and weed biomass that favored increased yield of maize over all cultivation treatments at higher N rates. The N content of weeds decreased as follows: conventional tillage < disc tillage < no‐till.

Spreading, ecology and damages caused by the common milkweed (Asclepias syriaca L.) in Hungary

One of the biggest challenges for the safe maize production is the yield stability in a wide range of environments with different soil fertility, weather conditions, prevailing pests and diseases as well as cultural practices. In order to achieve it, new hybrids with higher tolerance to biotic and abiotic stress are continuously being created. In order to compare performance of maize hybrids in environments with different levels and types of stress, and relate it to the stalk lodging incidence, we compared performance of 64 maize hybrids obtained by crossing 16 inbred lines with four inbred testers in three different environments. Two environments at same location (Rugvica) differed in crop rotation, and the third environment at location Botinec was considered as dry because of low water capacity of the soil. Mixed models that included all design elements and genetic background of hybrids were used to analyze the effect of lodging on yield in different environments. The results show that stalk lodging had a significant effect on yield, but significant lodging x environment interaction indicates that this effect was rather environment specific.Sweet pepper Istra F1 hybrid was grown in a greenhouse on K rich soil. For evaluation of K antagonism, two K rates (55 and 85 kg ha-1) were applied in a randomized complete block design with four replications. Total number of fruits, total number of BER affected fruits as well as average fruit mass were recorded for each harvest. Fruit and leaf K and Ca content were determined at three plant growth stages (at the stage of the first, third and fifth fruit cluster). Higher K rate gave higher : average fruit mass (169.45 g), total number of fruits per plant (7.95), number of BER affected fruits per plant (3.82), K in leaves (5.44% DM), K in fruits (6.35% DM), but negatively correlated with Ca concentration in fruits (0.57% DM) and leaves (3.24% DM). This resulted in decreased marketable yield of sweet pepper fruits.

Relationships Between Soil Characteristics and Weeds

Abstract Information technologies, such as the global positioning system and geographic information system, provide new opportunities for improving the efficiency of weed management, thereby resulting in a reduction in financial and environmental costs. Thus, an evaluation of data of systematic weed surveys carried out repeatedly at locations identified by geographical coordinates allows the establishment of relationships between weed associations and soil properties. Our quantitative survey targeted a 53‐ha agricultural field at Baracska, Hungary, with a total of 122 sampling sites. Soil properties (pH, texture, organic carbon, humus, and macro‐ and microelement contents [altogether 24 parameters]) were determined and weeds (frequency and density for 27 species) were recorded at the sampling sites. A distinct negative association between the crop yield (tightly linked to levels of nitrogen, phosphorus, and potassium fertilizers in the soil) and the total weed density at the sampling sites was demonstrated by principal component analysis of our data, indicating a good management of the project area that successfully increased the crop plants competitiveness with weeds.