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The climatic conditions in Hungary and in the countries to which seed is exported makes the study of maize cold tolerance and constant improvements in the cold tolerance of Martonvásár hybrids especially important. An improvement in the early spring cold tolerance of maize would allow it to be grown in more northern areas with a cooler climate, while on traditional maize-growing areas the profitability of maize production could be improved by earlier sowing, leading to a reduction in transportation and drying costs and in diseases caused by Fusarium sp. The recognition of this fact led Martonvásár researchers to start investigating this subject nearly four decades ago. The phytotron has proved an excellent tool for studying and improving the cold tolerance of maize. The review will give a brief summary of the results achieved in the field of maize cold tolerance in the Martonvásár institute in recent decades.

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The carbon balance of the sandy pasture (Bugac) and the mountain meadow (Mátra) varied between −171 and 96 gC m−2 year−1, and −194 and 14 gC m−2 year−1, respectively, during the study period (2003–2009). Large part of interannual variability of net ecosystem exchange (NEE) was explained by the variation of the annual sum of precipitation in the sandy grassland ecosystem, while this relationship was weaker in the case of the mountain meadow on heavy clay soil. These different responses are largely explained by soil texture characteristics leading to differences in soil water contents available to plants at the two grasslands. The grassland on heavy clay soil was more sensitive to temporal distribution of rainfall for the same reason. The mountain meadow therefore seems to be more vulnerable to droughts, while the sandy grassland is better adapted to water shortage. The precipitation threshold (annual sum), below which the grassland turns into source of carbon dioxide on annual basis, is only 50–80 mm higher than the 10 years average precipitation sum. In extremely dry years (2003, 2007 and 2009), even the sandy grassland ecosystem was not stable enough to maintain its sink character.

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Some agronomical characters of twelve single-cross maize hybrids were investigated at five different locations in Hungary over a three-year period. The characters examined were individual plant production (total mass of the ears on a single plant), thousand-kernel mass, number of kernel rows, ear length, number of kernels per row, shelling % and the assimilating leaf area above the main ear. Among these yield components, the individual plant production, the ear length, the number of kernels per row and the grain-cob ratio (shelling %) were influenced to the greatest extent by the year, followed by the variety and the location. The greatest average yield was achieved by the tested hybrids at all five locations in 1997 (263 g/plant). The average yields in 1998 and 1999 were significantly lower (221 and 203 g/plant, respectively). The outstanding yields achieved in 1997 could be attributed to the favourable ecological conditions, which led to the development of secondary ears in Keszthely and Sopronhorpács. At the other three locations there was only one ear per plant, but these ears were longer than in the following years. The greatest year effect was recorded in Sopronhorpács, where the individual plant production amounted to 305 g/plant in 1997 and 238 g/plant in the worst year, 1999. In Gyöngyös conditions were very dry in all three years, so the year effect was least pronounced at this location (grand mean of 195 g/plant in 1997 and 201 g/plant in 1999). Stability analysis was carried out using the coefficient of variance for individual plant production. Hybrids Mv 3, Mv 5, Mv 9 and Mv 12 were found to have the best adaptability. The shelling % was not significantly influenced by the location; the grain-cob ratio is relatively stable for maize hybrids. A correlation was found between the individual plant production and the leaf area above the main ear (R2=0.658). Hybrids with the largest leaf area above the main ear also had the greatest ear mass.

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The surface microbial contamination is of great interest, since these microbes can be potential sources of food-borne diseases. The purpose of this study was to determine and compare the microbial surface contamination of sour cherry (Prunus cerasus L.) produced by integrated and organic cultivation methods in Hungary. The effects of the growing area, year, and cultivar were studied on 62 samples. According to the results, the average microbial contamination of sour cherry is within a certain range, independently from the cultivar, growing area, and year. The frequency distribution of the surface bacterial, mould and yeast counts also did not show significant differences between the growing methods or cultivars. Principal component analysis ranked the sour cherry samples into seven groups on the basis of the level of microbial contamination. The discriminant analysis proved the correctness of the grouping. The grouping was independent from cultivars, growing methods, and years. No examined food-borne pathogen Salmonella spp. or Listeria spp. were found on the surfaces of sour cherry.

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Lactating crossbred Holstein-Friesian dairy cows (n = 331) were started on an Ovsynch regimen 68 ± 8.2 days after calving; 200 µg GnRH intramuscularly (i.m.) on Days 0 and 9, and 35 mg prostaglandin F2a i.m. on Day 7. Thirty-eight and 31 cows (11.5 and 9.4%, respectively) were in oestrus on Days 0 to 6 and 7 to 8, respectively, and inseminated, and the remainder were fixed-time inseminated (on Day 10). For these three groups, pregnancy rates (60-65 days after breeding) were 31.6, 38.7 and 34.0%, respectively (P = 0.82) and calving rates were 100, 100 and 89.9% (P = 0.23). In a preliminary trial, twelve lactating cows (45 to 60 days postpartum) with inactive ovaries were given 1500 IU eCG i.m.; 10 were in oestrus within 10 days after treatment (and inseminated) and eight of these were pregnant (30 days after breeding). The Ovsynch program resulted in acceptable reproductive performance in cyclic cows and eCG treatment has considerable promise for inducing oestrus in anoestrous cows.

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The breeding of hybrid maize now has a history of over 100 years. In 1908, George H. Shull was the first to report on the high yields, great uniformity and homogeneity of hybrids derived from a cross between two inbred lines. Following this discovery, consistent self-fertilisation over a period of six to eight generations was found to be an extremely efficient method for developing maize lines. From the mid-1970s, however, with the elaboration of the monoploid ( in vivo ) and microspore culture ( in vitro ) techniques, it became possible to develop homozygous lines within a year.With the help of an efficient plant regeneration system based on anther culture, large numbers of doubled haploid (DH) lines can be produced. In the course of the experiments the seed of DH plants selected over several years was multiplied and crossed with Martonvásár testers, after which the hybrids were included in field performance trials in three consecutive years (2005–2007). The aim was to determine whether the field performance of hybrids developed in this way equalled the mean yield of standards with commercial value. The data also made it possible to calculate the general (GCA) and specific (SCA) combining ability of the parental lines, indicating the usefulness of the parental components in hybrid combinations and expressing the extent to which a given line contributes to yield surpluses in its progeny.A total of 52 maize hybrids were evaluated in the experiments in terms of yield and grain moisture content at harvest. The combinations, resulting from crosses between 12 DH lines, one control line developed by conventional inbreeding and four testers, were found to include hybrids capable of equalling the performance of the standards, and four DH lines were identified as improving the yield level of their progeny. As the experiment was carried out on a very small number of genotypes, the results are extremely promising and suggest that, if the range of genotypes used to develop DH lines is broadened and the sample number is increased, it will be possible in the future to find maize hybrids, developed with in vitro DH parental components, that surpass the performance of commercial hybrids.

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The research, carried out in the Martonvásár phytotron in 2007, was aimed at determining how the leaf water potential of maize hybrids produced in direct and reciprocal crosses, and thus possessing different levels of seed vigour, changed as the result of water withholding in the flowering phenophase. In the case of the silage maize hybrids Mv 290 and Lima it was found that seedling vigour influenced the plant height (measured at 30 days) of adult plants. Crosses produced on chilling-sensitive female genotypes (GL, AM, H29), such as the hybrids Káma, Maraton and Hunor, proved to be unambiguously stress-sensitive if water was withheld for more than six days. In all cases drought stress reduced the relative quantum efficiency, irrespective of the crossing combination.

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Solar UV-B radiation is generally regarded as an environmental stress factor, causing harm to living organisms by damaging DNA, proteins, lipids and membranes. Increased UV-B radiation may affect plant life directly or indirectly, having an influence on photosynthesis and plant biomass. In many plants, including maize (which is one of the most important crops in the world), exposure to increased UV-B radiation causes the induction of UV-B absorbing compounds (e.g. flavonoids), which act as UV-B screens and reduce the dangerous levels and effects of this radiation in plant tissues and cells.This study aimed to reveal how Martonvásár maize inbred lines (bred under Central European environmental conditions) respond to increased UV-B radiation.

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Acta Agronomica Hungarica
Authors: Z. Hegyi, Z. Zsubori-Tóth, J. Pintér, and C. Marton

Experiments have been underway in Martonvásár for many years to develop leafy silage hybrids, which have a greater aboveground mass than conventional silage hybrids. The best hybrids for biogas production would be those that produce a large quantity of biomass and are rich in starch. The chief characteristic of leafy hybrids is that they have more leaves than normal hybrids. Due to this enhanced leaf area above the ear, the vegetative period of leafy genotypes is shorter, while the grain-filling period is longer, which has a positive effect on both yield and grain quality. The results of the present experiment show that during the anaerobic fermentation of the silage, leafy hybrids produced more biogas (640 l per 1000 g dry matter) than conventional hybrids (606 l per 1000 g dry matter). There were no significant differences between the methane contents of the leafy and non-leafy hybrids tested in the experiment. A strong positive correlation was found between biogas yield and the starch content of the silage, and a moderate positive correlation between biogas yield and the sugar content. The correlation between biogas yield and the lignin and protein contents was negative, in accordance with other literary data.

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A total of 96 hybrids from four maturity groups (FAO 200, 300, 400, 500) were tested in two years (2006, 2007) at two locations in Hungary (Martonvásár, Szarvas). Considerable differences were found between the years for the grain yield per hectare and for the grain quality parameters. In 2006 record yields were achieved at both locations, averaging 11.61 t/ha in Martonvásár and 12.20 t/ha in Szarvas, due primarily to well-timed irrigation in Martonvásár and to good rainfall supplies in Szarvas. In 2007 both locations suffered from drought, with less rainfall than average during the critical months of the vegetation period, which was partially compensated for by irrigation in Martonvásár, giving a yield average of 5.96 t/ha, while the hybrids grown in Szarvas had a yield average of 5.06 t/ha. The grain quality parameters exhibited a close correlation with the grain yield in the individual FAO maturity groups. Hybrids of the flint type, which have a short vegetation period, had high protein and oil contents, but the yield averages were low due to the slower rate of starch incorporation. Hybrids of the dent type have a longer vegetation period and more intense carbohydrate accumulation, but low protein and oil contents. In wet years and locations there was a higher rate of starch accumulation, while dry years are favourable for protein and oil accumulation. The Bravais correlation coefficient was calculated between the yield and the grain quality parameters (averaged over years, locations and varieties). A positive, moderately strong correlation (0.68) was found between the yield and the starch content, a negative, moderately strong correlation (−0.52) between the yield and the protein content, and a loose negative correlation (−0.19) between the yield and the oil content.

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