Plant regeneration via tissue culture is becoming increasingly more common in monocots such as maize (Zea mays L.). Pollen (gametophytic) selection for resistance to aflatoxin in maize can greatly facilitate recurrent selection and the screening of germplasm for resistance at much less cost and in a shorter time than field testing. In vivo and in vitro techniques have been integrated in maize breeding programmes to obtain desirable agronomic attributes, enhance the genes responsible for them and speed up the breeding process. The efficiency of anther and tissue cultures in maize and wheat has reached the stage where they can be used in breeding programmes to some extent and many new cultivars produced by genetic manipulation have now reached the market.
The effects of herbicides containing different active agents and applied at different times (early, normal and late post-emergence) were studied on a chernozem soil in the Hajdúság region of E. Hungary in stands of different hybrid maize genotypes. The results proved that the extent of weed cover was equally influenced by the forecrop and the year. In a drier year with wheat as the forecrop, moderate weed infestation was recorded, while with maize as the forecrop and more favourable water supplies, infestation was more severe. The hybrid did not have a significant effect on the extent of weed cover. Little (2-6%) or no visible phytotoxicity was observed in the maize hybrids as a consequence of post-emergence herbicide treatments. The yield-enhancing effects of the various herbicides changed in proportion to the weed cover (in comparison to the untreated weedy control). In the case of low weed cover (in 2002 the weedy control was 7.6-8.4%) there were yield increases of 0-500 kg ha-1, which increased to 700-2700 kg ha-1 in the case of moderate weed cover (in 2003 the weedy control was 27.4-35.1%) and to 3200-4200 kg ha-1 when weed infestation was severe (in 2004 the weedy control was 52.3-57.4%). The study proved that maize hybrids with different genotypes demonstrated general and specific types of herbicide sensitivity (active agent, timing of application).
The fertilizer response of oilseed rape (Brassica napus var. oleifera f. biennis L.) was investigated on the chernozem soil in Eastern Hungary in a three-year experiment with two sowing times. The results proved that oilseed rape had high fertilizer (N+PK) demand. In the experiments, N = 210 kg ha−1 +PK proved to be the optimal fertilizer dose. The yield-increasing effect of fertilization was 800 to 1300 kg ha−1, depending on the year. The maximum yield (5000 kg ha−1) was obtained in the year with least infection. The excellent natural nutrient-providing ability of chernozem soil was confirmed by the high yield level (3000–4200 kg ha−1) of the control treatment (N = 0 kg ha−1 +PK). The results showed that the specific fertilizer utilization efficiency of oilseed rape decreased if the dose of N+PK fertilizer was increased (being 19–27 kg/1 kg NPK in the control treatment and 11–12 kg/1 kg NPK in the N = 210 kg ha−1 +PK treatment). On the other hand, fertilization improved the water utilization from 4–8 kg/1 mm precipitation + irrigation water to 11–14 kg/1 mm precipitation + irrigation water. The results of these studies confirmed that hybrid rape had excellent adaptability to the sowing time. The results of Pearson’s correlation analysis showed a strong correlation (0.6*–0.9**) between the spring precipitation and temperature and the most important diseases (Sclerotinia, Alternaria, Peronospora, Phoma) attacking oilseed rape.
The interactions of ecological conditions, genotypes and agrotechnical elements determine the yield quantity, quality and stability in cereal (wheat, maize) production. The applied input- level can modify the adaptive capacity of crop models to ecological conditions. The effects of agrotechnical elements (crop rotation, fertilization, irrigation, crop protection, plant density) were studied in the long-term experiment on chernozem soil. Our scientific results proved that the high yields and good yield-stability were obtained in the input-intensive crop models, so these models had better adaptive capacity, high yield and resilience. Maize had lower ecological adaptive ability than winter wheat. The optimalization of agrotechnical elements reduces the harmful climatic effects so we can increase the yield and yield stability of cereals agro-ecosystems. The yields of wheat varied between 2 and 7 t ha−1 in extensive and 8 and 10 t ha-1 in intensive crop models and the yields of maize ranged between 2 and 11 t ha−1 and 10 and 15 t ha−1, respectively.
In our long-term experiment the analyses of stability were conducted in one shorter (years 2001–2003) and one longer (years 1994–2003) periods by using different numbers (2–6) of varieties in each one of the periods. The results of our research proved that the method, applied can be efficiently used to analyse the environmental responses, the behaviour under varying environmental conditions of different varieties. Varieties can adapt themselves differently to favourable and unfavourable environmental conditions. In general, varieties (e.g. older varieties, like Mv 15, Mv 20, and new varieties, like Lupus, Mv Emese) that give relatively good yields under unfavourable conditions (2–3 t ha
environmental average) will utilise improving environmental conditions (7–8 t ha
environmental average) to a lesser extent and vice versa. Varieties Mv 21, GK Öthalom and Mv Palotás (a currently cultivated variety) made good use of intensive growing conditions. The data in this paper may assist in choosing varieties best suited to the production and cultivation conditions of the production site.By applying stability analyses we proved that the stability of the control treatment was the most favourable over the investigation period, which good yield stability, however, manifested at very low yield levels. Our findings showed that under more intensive environmental conditions (7–9 t ha
yield level) appropriate and optimum fertilizer application was very effective and in comparison to the control treatment the yield differences between optimal fertilizer treatments were up to as much as 1–6 t ha
. Under favourable environmental conditions the highest yields were obtained when a fertilizer ratio of N
+PK was applied. Under unfavourable conditions (these may be either or both ecological and cultivation conditions), however, only retrained, moderate fertilizer doses are recommended. Under extremely unfavourable conditions (very dry cropping year) the linear regression curves for fertilizer treatments were below those of the control treatments, which referred to yield depressions due to water deficiency.
Cryopreservation appears to be a suitable solution for the maintenance of potato germplasms. The protocol described in this paper can be applied for the vitrification and preservation of meristems. During histo-cytological studies it is possible to observe modifications at the cellular level and to understand the adaptive mechanism to low temperatures. Control potato meristem tissue contained a number of meristematic cells with a gradient of differentiation. After freezing there were a large number of vacuolated cells, some of which exhibited broken cell walls and plasmolysis. The thickening of the cell wall, giving them a sinuous appearance, was observed after freezing and thawing the meristems, with ruptures of the cuticle and epidermal layer.
The effect of three technological factors (sowing date, fertilization, crop density) and two genotypes was examined on the yield and agronomic traits of sweet corn grown on chernozem soil in the Hajdúság region of Hungary. The experiments, conducted at the Látókép Research Site of the University of Debrecen, involved two sowing dates (end of April, end of May), six fertilization levels (control, N30 + PK, N60 + PK, N90 + PK, N120 + PK, N150 + PK) and two plant density levels (45 thousand ha−1, 65 thousand ha−1). Both hybrids used (Jumbo and Enterprise) belong to the mid-late maturity group. Compared to the 30-year average, the climate was dry and warm in 2009. Moisture deficiency had an adverse effect on the yield of crops sown at the second sowing date. By contrast, the second year (2010) was very humid; the precipitation was 184 mm above the 30-year average and the temperature was average.In the dry year the highest yield was obtained with Jumbo for both sowing dates (27253 kg−1, 20921 kg ha−1), while in 2010 Enterprise gave the highest yield (23437 kg−1, 22237 kg ha−1) for both sowing dates. The correlation between the technological factors, the yield and agronomic traits was analysed using Pearson’s correlation coefficient.
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.).
Soil water balance was studied in a 25-year-old experiment, on chernozem soil, in different crop-rotation systems (mono-, bi- and triculture) in dry (2007) and rainy (2008) seasons, in maize production. Soil water deficit values in maize production were much lower in 2008 than in 2007 in non-irrigated and irrigated plots of three crop rotation systems because of favourable precipitation supply. We found difference between the water deficit values of two irrigation treatments. We measured lower values in irrigated plots of three crop-rotation systems before sowing: non-irrigated plots in monoculture 105 mm, in biculture 101 mm, in triculture 121 mm and irrigated plots in monoculture 90 mm, in biculture 91 mm, in triculture 111 mm. Soil waterstock started to decrease with the rise in average temperature and, despite an increase in precipitation quantity, we calculated higher water deficit values. Precipitation in August and the high average temperature intensified the water deficit. Water deficit showed its highest values in early September. We examined the water balance of the soil profile in 0–2.0 m and we concluded that the water deficit of the 0.8–1.2 m soil layers was most intensive in both non-irrigated and irrigated treatments, because of significant root mass. Our results showed that irrigation had a more important influence on the yield in a dry cropyear (2007 characterized by abiotic, water stress) than in an optimum water supply cropyear (2008).
Different long-term experiments were carried on chernozem (Debrecen) and loamy (Hajdúböszörmény) soils. They included the most important agrotechnical, biological (hybrid) and agroecological (crop year, soil) factors in maize production. This paper evaluated the results of polyfactorial long-term experiments. For the maize the most favourable crop rotation was winter wheat (in a tri-culture) with an N 60–120, P2O5 60–70, K2O and 90–110 kg ha−1, and a density of 75–90,000 plants ha−1. The different input levels of maize crop management systems can modify an adaptive capacity to ecological conditions and the resilience of agro-ecosystems. The optimalization of agrotechnical elements reduces the harmful climatic effects. The yields of maize varied between 2–11 t ha−1 in extensive and 10–15 t ha−1 in intensive crop management systems, respectively.