We established a multifactoral long-term field experiment at the Látókép experimental site of the University of Debrecen (Debrecen, Hungary), on mid-heavy calcareous chernozem soil in 1984, using experimental data from 17 years (1990-2008). We examined the extent to which soil fertility affects maize yield under natural conditions (without fertilisation). We analysed the effect of precipitation in the winter period (from the harvest of the previous crop (maize) until sowing (i.e. October-March)) and the growing season (i.e. April-September) on yield and we evaluated yield per FAO group. We examined the joint effect of crop year and hybrid maturity groups on maize yield; then we evaluated how hybrid maturity groups per crop year and wet and dry years per ripening group affected maize yield. It was shown that the pH value of soil significantly affected yield and also that there was a strong positive correlation between pH value and yield (r = 0.81) at a 1% significance level. The correlation between the two variables is described by a linear regression line. The slope shows that a 0.1 soil pH increase results in a 510 kg ha-1 maize yield increase on average. The correlation between the amount of precipitation during the growing season and maize yield is average, positive (r = 0.718) and linear. Based on the parameters of the estimated regression line - within non-fertilised conditions - 1 mm increase of precipitation resulted in a 9 kg ha-1 increase in yield. The analysis of the joint effect of hybrid maturity groups and crop year on yield showed that crop year determines standard deviation six times more than hybrid maturity groups, whereas the effect their interaction was not significant. and Práca bsahuje výsledky multifaktorového, dlhodobého pokusu na experimentálnej ploche Látókép, Univerzity v Debrecíne (Debrecen, Maďarsko). Experiment prebiehal od roku 1984, v tejto práci boli použité údaje z experimentu získané počas 17tich rokov (1990-2008). Pôda je stredne ťažká černozem. Bol skúmaný vplyv pôdnej úrodnosti na úrodu kukurice v prirodzených podmienkach, bez hnojenia. Študoval sa predovšetkým vplyv zrážok počas zimného obdobia (od zberu úrody kukurice až po nasledujúcu sejbu, t.j. od októbra do marca) a vplyv zrážok počas vegetačného obdobia (apríl -september) na úrodu kukurice. Okrem toho sa študoval vplyv ''sezóny'' a skupín skorosti hybridov na úrodu kukurice. Bolo vyhodnotený tiež vplyv skupiny skorosti hybridov počas suchých a mokrých rokov na úrodu kukurice. Bolo preukázané, že hodnota pH pôdy významne ovplyvňuje úrodu; súčiniteľ lineárnej korelácie medzi pH a úrodou na úrovni významnosti 1% bol r = 0,81. Z tejto korelácie vyplýva, že zvýšenie pH o 0,1 spôsobuje zvýšenie úrody kukurice priemerne o 510 kg ha-1. Korelácia medzi úrnom zrážok počas vegetačného obdobia kukurice a úrodou je pozitívna a lineárna (r = 0,718), z analýzy vyplýva, že zvýšenie úhrnu zrážok o 1 mm spôsobí priemerné zvýšenie úrody kukurice o 9 kg ha-1. Z výsledkov analýzy spoločného vplyvu skupín skorosti hybridov a sezóny vyplýva, že konkrétna sezóna ovplyvňuje tvorbu úrod 6-krát významnejšie, ako skupina skorosti hybridov; interakcia medzi skupinami skorosti hybridov a vlastnosťami sezóny nie je významná.
Responses to drought were studied using two maize inbred lines (B76 and B106) and a commercial maize hybrid (Zea mays L. cv. Silver Queen) with differing resistance to abiotic stress. Maize seedlings were grown in pots in controlled environment chambers for 17 days and watering was withheld from one half the plants for an additional 11 days. On the final treatment date, leaf water potentials did not differ among genotypes and were -0.84 and -1.49 MPa in the water sufficient and insufficient treatments, respectively. Greater rates of CO2 assimilation were retained by the stress tolerant maize inbred line, B76, in comparison to the other two genotypes 11 days after watering was withheld. Rates of CO2 assimilation for all three genotypes were unaffected by decreasing the measurement O2 concentration from 21 to 2% (v/v). Activities of phosphoenolpyruvate carboxylase (PEPC), NADP-malic enzyme (NADP-ME), and NADP malate dehydrogenase were inhibited from 25 to 49% by the water deficiency treatment. Genotypic differences also were detected for the activities of NADP-ME and for PEPC. Changes of transcript abundance for the three C4 pathway enzymes also varied among watering treatments and genotypes. However, examples where transcripts decreased due to drought were associated with the two stress susceptible genotypes. The above results showed that enzymes in the C4 photosynthetic pathway were less inhibited by drought in stress tolerant compared to stress susceptible maize genotypes., R. Sicher, J. Bunce, J. Barnaby, B. Bailey., and Obsahuje bibliografii