Plant growth and potassium supply dynamics on a chernozem soil of a long-term fertilization and irrigation experiment with maize monoculture in Hungary
For the plant production used soil's nutrient supplying ability ideally should correspond to the needs 
of the plants. The aim of our experiment work is to study as precisely as possible, how the dynamics of 
growth and nutrient uptake of the maize plant develop during the vegetation period. For their 
determination the basis of our research work was a long-term irrigation and fertilization monoculture 
maize field experiment that has been set up in 1984 near to Debrecen, Hungary. The soil of this 
experiment is a medium-heavy, loam texture calcareous chernozem type based on loess. The deepness 
of humus soil layer is between 70 and 90 cm. Its upper layer has become leached due to the intensive 
production in the past decades, so it doesn't content any significant lime-amount. Therefore, the soil pH 
is slightly acidic in the production layer, which is favorable for nutrient-mobilization and -uptake. This 
field represents the production circumstances of the chernozem soils of Hungary with excellent 
productivity. Effects of three factors were studied: genotypes of maize (3), fertilizer dosages (6) and 
irrigation levels (2). The total number of investigated treatments (plots) was 36. Plant samples were 
collected 7 or 6 times during the vegetation period, and the above-ground dry matter and the nutrient 
uptake of plants were determined. For characterizing and describing of the plant growth and nutrient 
uptake dynamics was used the so-called “S-type” (acceleration – saturation) equation as follows: 
y=A/(1+exp(-k*(x-x0)))*(1-b*x), where “y” is the actual value of the measured (dependent) factor on the 
day “x” after plant shooting, “A” is the maximum value of “y”, “x0” is the day of maximum growth rate of 
“y” (point of inflexion) and “b” is the rate of decreasing of dependent value for one unit. According to 
our results and calculations it can be concluded, that beside the previously used soil and plant nutrientcontent 
the consideration and calculation of the plant-extracted nutrient-amount – depending on the 
applied hybrid and other agro-technological measurements – is suggested in order to characterize 
precisely the nutrient-supply of maize. This parameter informs us not only about the available nutrientamount 
at the sampling time, but about the supply level of the plants until the sampling time as well. 
We suggest for sampling times the intensive vegetative growth period, the switch between the vegetative 
and generative growth phases (silking), just as the grain-filling phase.
Changes in the quality of maize hybrids in various agricultural management systems
Changes in the chemical contents of the kernels of maize hybrids were analysed in three consecutive years (one dry, one arid and one wet) in samples originating from irrigation and fertilisation experiments. The results indicated that while irrigation and wet years had a protein-decreasing effect, the water supply did not influence the starch and oil contents. Under the influence of fertilization, the calcium and zinc contents of maize kernels decreased to varying degrees depending on the hybrid, while the sulphur contents changed parallel to the protein contents. Based on these data and on the use of more modern measuring equipment, tables giving recommendations for chemical contents should be revised.
A study of plant sample preparation and inductively coupled plasma emission spectrometry parameters
Abstract Adjustable parameters of an inductively coupled plasma emission spectrometer (ICP) are investigated and a digestion method of plant samples is developed which does not require the use of HC104. This HNO3‐H2O2 wet digestion method eliminates the hazards associated with hot, concentrated HClO4. The adjustable parameters of ICP are viewing height, forward power as well as the sample, coolant, auxiliary, and flushing gas flow rates, and the sample uptake flow rate. The digestion parameters examined are the type and amount of the applied acids (HNO3, HCl, and H2SO4), the temperature and duration of predigestion, the amount of H2O2, and the temperature and duration of digestion. Three plant samples (maize seed, wheat straw, and sunflower seed) and three dry weights are analyzed. The optimal parameters of the ICP spectrometer and HNO3‐H2O2 wet digestion for plants are determined. Optimal parameters of HNO3‐H2O2 wet digestion sample preparation: Optimal parameters of the ICP instrument: