Never has the need been greater for an ecosystem approach to agriculture. As our global population exceeds 9 billion in the next 30 years, with a concomitant demand for agricultural products, ever more pressure will be placed on our agricultural systems. Meanwhile, climate change is altering the ecological settings in which agriculture is pract...iced, demanding adaptation. Knowledge generated by long-term research will help to address one of the grand challenges of our time: how to meet sustainably the growing world demand for agricultural products – in a way that minimizes environmental harm and enhances the delivery of a diverse array of ecosystem services.
The results of experiments carried out in the Agricultural Research Institute of the Hungarian Academy of Sciences clearly show that in the case of hybrids grown in a monoculture greater fertiliser responses can be achieved with increasing rates of N fertiliser than in crop rotations. In the monoculture experiment the parameters investigated re...ached their maximum values at a rate of 240 kg/ha N fertiliser, with the exception of 1000-kernel mass and starch content. In both cases the starch content was highest in the untreated control, gradually declining as the N rates increased. Among the parameters recorded in the crop rotation, the values of the dry grain yield, the 1000-kernel mass, the protein yield and the starch yield were greatest at the 160 kg/ha N fertiliser rate, exhibiting a decrease at 240 kg/ha. Maximum values for the protein content and SPAD index were recorded at the highest N rate. It is important to note, however, that although the N treatments caused significant differences compared to the untreated control, the differences between the N treatments were not significant.
In the given experimental year the values achieved for the untreated control in the crop rotation could only be achieved in the monoculture experiment at a fertiliser rate of 160 kg/ha N, indicating that N fertiliser rates could be reduced using a satisfactory crop sequence, which could be beneficial from the point of view of environmental pollution, crop protection and cost reduction.
The weather in 2006 was favourable for maize production, allowing comparative analysis to be made of the genetically determined traits of the hybrids. Among the three hybrids grown in the monoculture experiment, Maraton produced the best yield, giving maximum values of the parameters tested at a fertiliser rate of 240 kg/ha N. The poorest results were recorded for Mv 277, which could be attributed to the fact that the hybrid belongs to the FAO 200 maturity group, while the other hybrids had higher FAO numbers. Maraton also gave the highest yields in the crop rotation experiment at the 160 kg/ha N level. All three hybrids were found to make excellent use of the natural nutrient content of the soil.
It was proved that the protein content of maize hybrids can only be slightly improved by N fertilisation, as this trait is genetically coded, while the starch content depends to the greatest extent on the ecological factors experienced during the growing season.
The effect of crop production factors on the grain yield was analysed on the basis of three-factorial experiments laid out in a split-split-plot design. In the case of maize the studies were made as part of a long-term experiment set up in 1980 on chernozem soil with forest residues, well supplied with N and very well with PK. The effects of fi...ve N levels in the main plots and four sowing dates in the subplots were compared in terms of the performance of four medium early hybrids (FAO 200). In the technological adaptation experiments carried out with durum wheat, the N supplies were moderate (2010) or good (2011), while the P and K supplies were good or very good in both years. Six N top-dressing treatments were applied in the main plots and five plant protection treatments in the subplots to test the responses of three varieties.
The results were evaluated using analysis of variance, while correlations between the variables were detected using regression analysis.
The effect of the tested factors on the grain yield was significant in the three-factorial maize experiment despite the annual fluctuations, reflected in extremely variable environmental means. During the given period the effect of N fertilisation surpassed that of the sowing date and the genotype. Regression analysis on the N responses for various sowing dates showed that maize sown in the middle 10 days of April gave the highest yield, but the N rates required to achieve maximum values declined as sowing was delayed.
In the very wet year, the yield of durum wheat was influenced to the greatest extent by the plant protection treatments, while N supplies and the choice of variety were of approximately the same importance. In the favourable year the yielding ability was determined by topdressing and the importance of plant protection dropped to half, while no significant difference could be detected between the tested varieties. According to the results of regression analysis, the positive effect of plant protection could not be substituted by an increase in the N rate in either year. The achievement of higher yields was only possible by a joint intensification of plant protection and N fertilisation. Nevertheless, the use of more efficient chemicals led to a slightly, though not significantly, higher yield, with a lower N requirement.
The tolerance of 15 inbred maize lines grown on chernozem soil with forest residues in Martonvásár was tested against herbicides applied post-emergence in two dry, warm years (2003 and 2011) and in two cool, wet years (2004 and 2010). The herbicides mesotrione + terbutylazine, nicosulfuron and dicamba were applied to maize inbred lines in the... 7–8-leaf stage at the maximum dose authorised for practical use and at double this rate. The plants were scored for the intensity of visible phytotoxic symptoms 14 days after treatment.
The level of phytotoxicity observed in dry, warm years was 5.14%, averaged over the lines, herbicides and rates. The intensity of visible symptoms was almost 2.5 times as great in cool, wet years (12.76 %).
Averaged over the four years, the lines and the rates, the least damage was caused by dicamba (5.77 %), followed by mesotrione + terbutylazine (7.23 %). The most severe symptoms were induced by nicosulfuron (16.17 %). This could be attributed to the fact that some of the inbred lines were extremely sensitive to herbicides, especially those of the sulfonylurea type.
A difference of more than 1.5 times was observed between the two doses, but the correlation between the concentration and the severity of the visual symptoms was not strictly linear. Compared to the normal dose (100 %) the double rate resulted in a 162.5% increase in symptom severity. In most cases plants treated with the normal dose were symptom-free or only exhibited a low level of phytotoxicity.