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  • Author or Editor: V. Kovačević x
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Wheat is the second most important field crop on arable lands in Hungary and Croatia. Yield variations between years are high in both countries. In the short term these variations are mainly the result of the weather parameters specific to individual growing seasons. The aim of this study was to compare variations in winter wheat yields over years in four counties in Hungary and five in Croatia, with the emphasis on the impact of rainfall and mean air temperature regimes. The results showed that rainfall in spring was most decisive for winter wheat yields. The highest winter wheat yields were obtained when the rainfall in the winter half-year ranged from 230–260 mm and the spring rainfall from 180–230 mm. The precipitation in the growing season is much higher in eastern Croatia than in eastern Hungary, so water shortage is a more pronounced environmental problem for wheat in Hungary. This is probably why wheat yields were lower in eastern Hungary than in eastern Croatia in the period tested. Pearson correlation analysis on the yields and meteorological data between 1990 and 2009 revealed a positive correlation between spring rainfall and the yield, and a negative correlation between spring temperature and the yield. The results proved that yields were determined not only by weather conditions, but by many other factors (crop rotation, tillage, fertilization, variety, crop protection, etc.).

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Authors: V. Kovacevic, D. Banaj, J. Kovacevic, A. Lalic, Z. Jurkovic and M. Krizmanic

Aim of this study was testing of field crops (maize-maize-sunflower-winter barley rotation) to lime (carbocalk: waste of sugar factory, 39% CaO) application in five rates up to 90 t/ha. Field trial was conducted in autumn 2000 in four replicates. Liming with carbocalk resulted with considerable increases of field crop yields as follows: up to 50% and 36% (maize for 2001 and 2002, respectively), up to 49% (sunflower 2003) and up to 30% (barley 2004). In general, by application of carbocalk to level of 90 t/ha, yields drastically decreased mainly to level of control as affected by over liming. Concerning oil contents in sunflower grain, it was significantly higher compared to control for treatments 15, 30 and 45 t/ha, but similar for control and 60 t/ha. Using of 45 and more lime per hectare decreased grain quality of malting barley because protein contents were significantly increased.

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Oil crops constitute the second most important field crops worldwide and are important both in Hungary and Croatia. Among the oil crops, sunflower has a significant role in Hungary (∼550,000 ha) and Croatia (∼30,000 ha). The main aim of this study was to compare sunflower yields and their variation over years (2000–2007) in the eastern parts of Hungary and Croatia, with the emphasis on the impact of rainfall and temperature regime, and using a rain factor (RFm) calculated monthly as the quotient of precipitation (mm) and mean air temperatures (°C). The results showed that the year had a different effect on the yield of sunflower in the different counties of eastern Hungary and Croatia, because of their different soil conditions. The results proved that the highest yields of sunflower (2140–2710 kg ha−1) were obtained in years when the rainfall before and during the vegetation period was 110–130 mm and 350–420 mm, which was very similar to the 30-year mean data (82–108 mm and 305–346 mm, respectively). The strongest correlations (positive and negative r values) between meteorological data and sunflower yields were found in counties with unfavourable soil conditions. In counties with better soil fertility the correlation coefficients were smaller, indicating that better soil conditions can compensate for unfavourable year effects (especially temporary shortage of rainfall or unfavourable rainfall distribution).

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Drought and soil acidity are two major abiotic stress factors limiting maize production worldwide, generating imbalances in the manganese (Mn) and zinc (Zn) status in plants. This study was conducted to determine the effects of drought stress on the Mn and Zn status in maize genotypes grown on acid and non-acid soils and how the Mn and Zn status affects the changes in grain yield caused by drought stress and soil acidity. Seventeen genotypes were grown at two locations differing in soil acidity in Eastern Croatia in 2003 and 2004. Positive values of an aridity index indicated drought stress in 2003. The genotypes had much higher Mn and Zn concentrations on acid soil than on nonacid soil: more than twice as high in both seasons for Zn and about 6 and 9 times higher in normal and in dry seasons, respectively, for Mn. This demonstrates that drought combined with soil acidity led to the excessive accumulation of Mn in maize plants. However, variation was observed between the maize genotypes for the Mn accumulation on soils differing in acidity when drought occurred. Some genotypes accumulated Mn on acid soil irrespective of drought. The Mn and Zn status had no discernible effect on the changes in grain yield caused by drought stress and/or soil acidity.

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Authors: D. Banaj, V. Kovacevic, D. Simic, M. Seput and B. Stojic

The field experiment with three rates of phosphorus (P) fertilization for maize (OsSK444 and OsSK552 hybrids) up to 2000 kg P 2 O 5 /ha were conducted in the spring 2002. For the next growing seasons (2003 and 2004) only ordinary fertilization was applied. In general, maize yields were independent on applied fertilization. Only application of the highest P rate had residual influences on maize yields for the 2003 growing season. Probably very favorable weather conditions for 2002 and 2004 could be responsible factor for low influences of fertilization on maize yields. Also, maize hybrid OsSK552 yielded more than OsSK444. The ear-leaf of maize at beginning of silking (the 2002 growing season only) was taken for chemical analysis. Leaf P, Mg, Mn and Fe concentrations increased by application of the highest rate of P. At the same time, K, Ca, Zn, Cu and Fe concentrations significantly decreased. Especially influences of P fertilization were found for Zn status in maize leaves (70 and 40 ppm Zn, for the control and 2000 kg P 2 O 5 /ha, respectively). OsSK552 hybrid characterized by the higher K, Ca, Mg, Cu and Fe, as well as the lower Zn concentrations in comparison with the OsSK444 hybrid.

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Authors: Z. Loncaric, V. Kovacevic, Miranda Seput, B. Simic and Biserka Stojic
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Increased rates of P and K (monoammonium phosphate and potassium chloride) were applied in four replicates on two soils in spring 2001 as follows: a) standard fertilization (kg ha −1 : 177 N + 100 P 2 O 5 + 150 K 2 O); b) a + 1500 kg P 2 O 5 ha −1 ; c) a + 1500 kg K 2 O ha −1 ; d) = b + c. Residual effects of the fertilization were tested in the next year. Maize (OsSK552 hybrid) growing on Luzani soil resulted in 15% lower yield compared to the Kobas soil (7.75 and 9.06 t ha −1 , respectively). Mean the leaf (the ear-leaf at silking) concentrations (mg kg −1 ) were 41.8 (Zn), 14.1 (Cu) and 131 (Fe), respectively. The leaf Mn was by 60% lower and the leaf Zn by 16% higher in 2002 compared to 2001. Maize grown in the Luzani trial had by 9% lower the leaf Zn, 10% lower the leaf Cu and by 37% higher the leaf Mn compared to the Kobas soil. Under the influence of P fertilization, the leaf Zn decreased by 37% compared to the control. Application of both P and K resulted in decreases of leaf Zn by 30%. However, P fertilization, alone or in combination with K, increased the leaf Mn for 111% and 72% respectively. Significant difference the leaf Cu (by 9% lower) was found under influences K fertilization only. The leaf Fe was independent on these factors.

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Authors: V. Kovačević, M. Rastija, D. Rastija, M. Josipović and M. Šeput

Five maize ( Zea mays L.) hybrids were grown for four growing seasons on gleysol characterized by moderate supply with potassium (K). Three rates of KCl were applied in four replicates at the beginning of April 2001 as follows (kg K 2 O/ha): 150 (control), 650 and 1400. The highest rate of KCl resulted in significant increases of yield of 14%, 24% and 12%, for 2001, 2002 and 2003, respectively; while in the fourth year similar yields to the control were found. The OsSK552 and Bc5982 hybrids (4-year mean 8.70 t/ha) were more susceptible to soil stress in comparison with OsSK444 and OsSK458 (mean 9.07 t/ha). At the same time, Florencia hybrid yielded 9.37 t/ha. Four hybrids responded similarly to applied fertilization (yield increases from 13 to 16% in comparison to the control), while Florencia had low response to KCl (yield increase for 5% only). Under these conditions we recommend combined solution using 1000 kg K 2 O/ha every third year and a choice of tolerant hybrids.

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Authors: M. Marković, P. Pepó, M. Sárvári, V. Kovačević, J. Šoštarić and M. Josipović

In the decade from 2000 to 2009, the yield of maize grain in Croatia varied from 4.2 t ha−1 (2003) to 8.0 t ha−1 (2008). The yield variation was mainly caused by weather conditions unfavourable for maize production, meaning lack of precipitation, unevenly distributed during the vegetation season, and mean air temperatures above the long-term mean. Irrigation has become a justified and essential agrotechnical measure that minimizes the damage caused by water deficit during critical plant growth stages and ensures high yields with good quality. In this paper two vegetation seasons (2006 and 2007) with quite different weather conditions for maize production were analysed in order to examine the importance of irrigation in terms of yield increase, irrigation water use efficiency (IWUE), irrigation efficiency (IE) and irrigation water use index (IWUI) in years favourable (2006) or too dry (2007) for maize production. The yield surpluses achieved with irrigation ranged from 8.54 t ha−1 to 9.62 t ha−1 in the average crop year (2006) and from 8.43 t ha−1 to 10.7 t ha−1 in the dry year (2007), depending on the irrigation method. In the dry year the values of IWUE where higher than in the average year (6.16 and 13.75 kg ha−1/mm, respectively, averaged over the hybrids).

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Authors: I. Liović, A. Mijić, M. Krizmanić, P. Pepó, V. Kovačević, A. Markulj, T. Duvnjak and G. Krizmanić

Environmental conditions (soil, weather) have the greatest impact on the production of all crops, so it is necessary to check the behaviour of new hybrid combinations under diverse environmental conditions. In 2009 and 2010, field trials were sown at various locations in Croatia to test new sunflower hybrid combinations bred at the Agricultural Institute in Osijek. In both years, the trials were conducted in Beli Manastir (BM09 and BM10), Nova Gradiška (NG09 and NG10) and Osijek (Os09 and Os10), while in 2010, a trial was also sown in Vukovar (Vu10). The genotypes included three cytoplasmic male sterile lines (cms 1–3) as female parent with a set of 8 fertility restorer lines (four branching restorers: oG1–4 and four single-headed restorers: oM5–8). The grain yield data were processed for years and locations (7 environments) using analysis of variance (ANOVA) and Additive Main effects and Multiplicative Interactions (AMMI) analysis with the SAS for Windows 9.1 statistical software. To obtain a better picture of the grain yield stability of the hybrid combinations in different environments, AMMI1 and AMMI2 biplots were made using IRRISTAT for Windows 5.0 software. No significant differences were found between the hybrid combinations of the female lines (cms 1–3). Among the environments, the significantly highest grain yield was recorded in the environment Os09 (4.220 t ha−1), followed by BM09 and Os10. As regards the restorers the highest grain yields (statistically on par with each other) were found for hybrid combinations involving oG2 and oM7 (3.726 and 3.666 t ha−1). Together, the first two interaction principle components (IPC) explained 85.4, 76.6 and 64.8% of the variability for crosses involving cms1, cms2 and cms3, respectively. The AMMI1 and AMMI2 biplots showed that the highest yielding hybrid combinations did not have the most stable grain yield. The greatest stability was shown by restorer line oM7 in cross combinations with inbred lines cms1 and cms2, while the same restorer line exhibited a large genotype × environment interaction and low stability when crossed with cms3.

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