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  • Author or Editor: Z. Berzsenyi x
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Investigations on the process of dry matter accumulation over time could contribute to improvements in the N fertiliser utilisation of maize hybrids. In 2001 and 2002 the effect of four N fertiliser rates (0, 80, 160, 240 kg ha −1 ) on the growth and productivity of three maize hybrids with different vegetation periods [Mv TC 272 (FAO 280), Mv 355 SC (FAO 390) and Maraton SC (FAO 450)] was studied in an almost 50-year-old long-term experiment involving continuous maize, as a stress environment. The experiment was set up in Martonvásár on chernozem soil with forest residues in a split-plot design with four replications, with the N treatments in the main plots and the maize hybrids in the subplots. Plant samples for yield analysis were taken at 14-day intervals on 8 occasions a year. The dynamics of dry matter accumulation in the whole plants and in various plant organs (stalk, leaf, grain), and that of leaf area, differed significantly between N treatments and hybrids. The effect of mineral N fertilisation was significant from the 4–6-leaf stage and the differences between hybrids from the flowering stage. Both the dry matter yield and the leaf area were greatest in the N 160 treatment. The greatest difference in the pattern of N fertiliser reactions over time was detected between the pre-flowering and post-flowering stages. The maize grain yield was greatest in the N 160 treatment, exhibiting the following values (t ha −1 ) in the individual N treatments: N 0 : 4.907, N 80 : 7.872, N 160 : 8.921, N 240 : 8.770. The results indicate that the dynamics of dry matter accumulation in the whole maize plant and in various plant organs could further our understanding of the N fertiliser responses of maize hybrids.

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The use of growth analysis and growth parameters could make an important contribution to improving the utilisation of N fertiliser by maize hybrids. In 2001 and 2002 the effect of four N fertiliser rates (0, 80, 160, 240 kg ha −1 ) on the growth and productivity of three maize hybrids with different vegetation periods was studied in a long-term experiment involving continuous maize, representing a stress environment, set up in Martonvásár on chernozem soil with forest residues almost 50 years ago. Each year eight samples were taken at 14-day intervals for the destructive method of growth analysis. N fertiliser was found to have a significant effect on the growth parameters of individual plants (RGR, NAR, LAR) in both the vegetative and generative stages of growth, up to N rates of 80 and 160 kg ha −1 , respectively. The value of RGR increased until the N 160 treatment and that of NAR until N 80 , while LAR declined significantly in response to N fertilisation. RLGR was enhanced by N fertiliser up to a rate of N 80 , and all the N treatments reduced the extent of leaf withering. Among the growth parameters of the canopy, the values of CGR and HI rose significantly up to N 160 and that of LAI max up to N 80 . The cumulative values of LAD and BMD were highest in the N 160 treatment. All the growth parameters increased as the vegetation period of the hybrids lengthened, and all reflected the year effect. Compared to the highest N rate, N stress of 29–38% was calculated for the control treatment. On average, N fertilisation resulted in a 6–27% relative decline in LAI after flowering.

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Long-term experiments are indispensable for investigations on the long-term effects of various crop production methods and technologies. The long-term experiments set up in Martonvásár by Béla Győrffy are now 50 years old and can be considered as part of the national heritage. The most important of these experiments involve crop rotation vs. monoculture trials, the comparison of fertilisation systems, studies on the interactions and carry-over effects of organic and mineral fertilisers, fertiliser rate experiments and polyfactorial experiments. The long-term experiments in Martonvásár form an integral part of maize and wheat research and provide a place for testing the agronomic responses of maize hybrids and wheat varieties. Valuable scientific results are obtained from these experiments regarding the reasons for yield depression in monocultures, the yieldincreasing effect of crop rotations, the comparative benefits of organic and mineral fertilisation, the agronomic responses of genotypes, the sustainability and yield stability of crop production techniques, and the interaction between various crop production factors. These results promote the improvement of maize and wheat production and are regularly incorporated into recommendation systems. The present generation of scientists has a responsibility to maintain these experiments, so that they can continue to serve their purpose in the coming decades.

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Using the classical and functional methods of growth analysis, the effect of mineral N fertiliser (0, 80, 160 and 240 kg ha −1 ) on the dynamics of growth and growth parameters was studied in 2001 and 2002 in a two-factorial, long-term experiment set up in a split-plot design on three maize hybrids with different genotypes, Mv 272 (FAO 280), Mv 355 (FAO 390) and Maraton (FAO 450). The following growth parameters were calculated to characterise the effect of N fertiliser: the absolute growth rate (AGR, ALGR), the relative growth rate (RGR), the leaf area index (LAI), the net assimilation rate (NAR) and the harvest index (HI).Similar tendencies were found for the yield response of maize and the values of the growth parameters as a function of N fertilisation. Based on the results of principal component analysis, multiple regression analysis and discriminant analysis, the parameters AGR, LAI max , ALGR and HI were found to have a decisive influence on the grain yield of maize. It could be concluded from the results that growth parameters can be used to predict the N fertiliser responses of maize in early growth stages.

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A. R. Overman and R. V. Scholtz III.: Mathematical Models of Crop Growth and Yield. Marcel Dekker, 270 Madison Avenue, New York, NY 10016. 2002. Hardcover, 344 pp., 150.00. ISBN 0-8247-0825-3.

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The research agenda for crop science in the 21st century will depend largely on whether the present conditions regarding the global food surplus continue, or whether a food scarcity recurs. Crop production research is based chiefly on small-plot field experiments, the majority of which are either long-term experiments or experiments set up to investigate the specific agronomic responses of Martonvásár maize hybrids and wheat varieties. The sustainability of crop production is examined in long-term experiments. The agronomic responses of maize hybrids and wheat varieties are studied at various levels of biological organisation. Growth analysis facilitates the exact characterisation of agronomic responses and the grouping of response effects and types using multivariable methods. Continued experimentation coupled with crop simulation models and decision support systems are an ever more useful framework for analysing the complexity of agricultural systems.

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The effect of four rates of nitrogen (N) fertilisation (0, 80, 160, 240 kg ha−1) on the growth and yield components of three winter wheat varieties with different maturity dates (Mv Toborzó — extra early, Mv Palotás — early, Mv Verbunkos — mid-early) was analysed in a long-term experiment laid out in a two-factorial split-plot design with four replications in the years 2007–2009. The dry matter production of the whole plant and of individual plant organs, the maximum leaf area, the area of the flag-leaf and all the yield components except the thousand-kernel weight were significantly the greatest in the N160 or the N240 treatments. Averaged over the varieties and years the grain yield in the N treatments was N0: 5.5, N80: 7.1, N160: 7.3 and N240: 7.5 t ha−1. Averaged over N treatments and years the variety Mv Verbunkos had the highest dry matter production, stem mass, spike mass, number of grains per spike and grain yield. Mv Verbunkos had the greatest leaf area in the favourable years of 2008 and 2009 and the greatest flag-leaf area in 2008. Averaged over N treatments and varieties the dry matter production per plant, the leaf and stem mass, the number of spikes per square metre and the thousand-kernel weight were greatest in 2007. The spike mass was lowest in 2007 and had higher, very similar values in 2008 and 2009. The maximum leaf area per plant, the area of the flag-leaf, the number of grains per spike and the grain yield were highest in 2008. The values and dynamics of the growth parameters gave a good characterisation of the effect of the treatments (N fertilisation, variety, year) on plant production (yield, yield components) in various stages of growth.

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The growth dynamics determining the yield of winter wheat depends partly on genetic determination and partly on environmental factors, including nutrient supplies. Growth and yield responses to nutrient supplies were investigated for three diverse genotypes. In the dry year of 2007 dry matter production and leaf area were influenced chiefly by N supplies, while in the more favourable year of 2008 the genotypic effect was more pronounced, and in most cases N fertiliser only led to a significant increase in yield up to a rate of 80 kg ha −1 . The maximum value of the leaf area index (LAI) was recorded at the 240 kg ha −1 N level for all three varieties in 2007 (11.5; 9.9; 8.1), while in 2008 the maximum was observed at the 160 kg ha −1 N level for Mv Toborzó and Mv Palotás (8.6 and 8.4, respectively), and only in Mv Verbunkos did LAI continue to increase up to 240 kg ha −1 N (9.8). The cumulative BMD and LAD parameters mostly exhibited much higher values in 2007 than in 2008. The maximum grain yield was achieved at 160 kg ha −1 N in 2007 and at 80 kg ha −1 N in 2008. It could be concluded from the results that the manifestation of genotypic traits was enhanced by favourable weather conditions, which also led to the better utilisation of lower rates of N fertiliser.

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The effect of nitrogen (N) fertilisation on the growth of winter wheat varieties was examined in three diverse years using the functional method of growth analysis. The main plot in the two-factorial, split-plot experiment was the N treatment and the subplot the variety. The wheat varieties Mv Toborzó (extra-early), Mv Palotás (early) and Mv Verbunkos (mid-early) were treated with N rates of 0, 80, 160 and 240 kg N ha−1 (N0, N80, N160, N240). The Hunt-Parsons (HP) program fitted a third-degree exponential function to the dry matter and leaf area data. In 2007 and 2008 dry matter accumulation continued up to the N240 rate and in 2009 to the N160 rate. In all three years the highest value was recorded for Mv Verbunkos (4.62 g plant−1 in 2007, 4.63 g in 2008 and 4.51 g in 2009). The highest value of maximum leaf area (237.5 cm2) was found for Mv Verbunkos in the N240 treatment. The maximum values of leaf area in each N treatment, averaged over years and varieties (cm2 plant−1), were as follows: N0: 86.2; N80: 141.0; N160: 164.0; N240: 173.1. The parameter AGRmean exhibited the highest value (8.04 g day−1 102) in the N160 treatment, while among the varieties Mv Verbunkos had the highest mean value (7.18 g day−1 102). The highest value of RGRmean was achieved by Mv Toborzó in the N160 treatment in 2009 (3.94 g g−1 day−1 102). The value of NARmean increased up to fertiliser rates of N160 and N240, with mean values (g m−1 day−1) of N0: 2.35, N80: 2.44, N160: 2.53 and N240: 2.47. The highest value of NAR (3.29 g m−1 day−1) was obtained for Mv Palotás in the N160 treatment in 2008. On average the greatest value of LARmax was recorded in the N160 treatment (172.8 cm2 g−1), while the highest absolute value (213.6 cm2 g−1) was achieved by Mv Toborzó in 2008. The unfavourable effect of the drought in 2007 was clearly reflected in the values of the growth parameters.

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In maize, plant density has a considerable influence on the rate of dry matter accumulation and on its partitioning between vegetative and reproductive sinks. The aim of the present research was to use the first, second and third derivatives of the Richards function (RF) for growth analysis on maize hybrids grown at various densities. In two-factorial split-plot experiments carried out in Martonvásár, Hungary in 1997–1999 the growth analysis method was used to examine the effect of six plant densities (20, 40, 60, 80, 100 and 120 thousand plants ha −1 ) on the growth of three maize hybrids (Mara, Mv 355, Florencia) with different vegetation periods. Plant density had a significant effect on the dynamics of dry matter accumulation, absolute growth rate (AGR) and absolute acceleration rate (AAR). There was a significant reduction in the asymptotic maximum (A) and growth parameters (AGR, AAR) of the whole plant and of the individual plant organs (stalk, leaf, ear and grain yield), while the parameters of the leaf area index (LAI) increased significantly with a rise in the plant density. The usefulness of the RF for approximating the growth processes of maize plants and individual plant parts was confirmed statistically.

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