The common smut of maize (corn smut, Ustilago maydis /DC/ Corda) can cause large economic losses in susceptible sweet corn hybrids as well. The protection against this pathogen is fundamentally based on prevention. Many methods to control corn smut have been recommended or evaluated, including crop rotation, sanitation, seed treatments, modific...ation of fertility, and biological control. In spite of these frequently mentioned control strategies, the host resistance seems to be the only effective method to manage common smut in those areas where Ustilago maydis is prevalent.
Corn smut disease (Ustilago maydis) is one of the most common maize diseases. In the previous years the disease lost some from its importance, however nowadays it turns into more and more important and widespread one. The control encounters great difficulties, therefore it should be emphasized the preventive and resistance-based protection.
Common smut disease of maize is one of the most frequent diseases of crop. In the last decades the importance of disease has decreased in feeding maize production, however its importance increasing again nowadays, especially at sweet maize hybrids. The aims of this work was to find hybrids possess of resistance, and to evaluate which ones are m...ore or less susceptible under field artificial inoculation circumstances. Among feeding maizes the less susceptible hybrid was ‘P9578’, and the most susceptible ’NK Columbia’ hybrid, and differences in cob infection between them was significant (8.8%). At sweet corn hybrids the less susceptible was ’Prelude’, while the most susceptible was ’Jumbo’ with very high significant 74.6% differences.
The leaf chlorophyll content analysis is important for several reasons. The natural or anthropogenic stressors directly effect on the chlorophyll content. Through the measurement of the chlorophyll content it is possible to obtain data concerning the physiological status of the plant, moreover the chlorophyll content is closely related to the n...itrogen content, so it is linked to photosynthesis and the photosynthetic activity which determine biomass production.
One of the most common symptoms of plant diseases is the larger and smaller interveinal chlorotic areas. These might be local, or expand to the whole plant. There are multiply reasons of chlorosis such as reduction of chlorophyll content, unfavorable effects on the chlorophyll content,disorders regarding function of chloroplasts or ultimately destruction of the chloroplasts. Although such a chlorotic deviancy can contribute to significant losses in photosynthesis; however the underperformance photosynthesis of the sick plants is a more complex process.
As we unambiguously experienced during our investigations on common smut that the infected maize plants most common accompanying symptom was chlorosis on the leaves, so it is especially important to examine how the infection influenced on the chlorophyll content of different hybrids.
Corn smut disease is one of the most common maize diseases. In the previous years the disease lost from its importance, however nowadays it is becoming more and more important and widespread. The protection against it encounters great difficulties, therefore it is important to emphasize prevention and resistance based protection. The aim of the... research was to investigate under laboratory circumstances the resistance of Hungary’s most commonly cultivated maize hybrids to corn smut disease. Twelve species were investigated. We distinguished two susceptibility groups within the hybrids based on the investigated parameters. The results are intended to assist the protection against corn smut disease and to make a suggestion for the farmers so that they could apply more environmental friendly and economical production.
The amounts of Fe, and Zn were measured in maize seedlings infected by smut gall tumour (Ustilago maydis Dc. Cda.) and in healthy seedlings five days after infection. The amount of elements was also measured under different stress intensities. Due to the infection, as a biotic stress, the amount and distribution of examined elements have been c...hanged. On the bases of the differences in the Fe distribution between the symptoms less and tumorial leaf parts, we have come to the conclusion that the infection also effects the mobilisation of Fe and Zn inside the plants. The Fe uptake was much higher in the infected plants and the tumour development also had an effect on the uptake and distribution of the examined elements. The experiments of infecting maize seedlings by monosporidial strain of crown gall tumour showed no tumour development. We found that the monosporidial strain also acts as a biotic stress and has an effect of iron and zinc distribution. We observed a slight difference in the iron and zinc contents in the roots of corn seedlings infected by different monosporidial sporidium concentrations, while the iron and zinc contents in the shoots were increased by the intensity of the infection. The roots do not form tumours. There is no difference between the roots of the infected and healthy corn seedlings. Since the Fe and Zn contents of the shoots of infected plants depend on the intensity of the infection, we have come to the conclusion that there must exist a „special” communication system regulating the transportation of the examined elements.
In the experiments with infected maize seedlings, it became necessary to get the iron chlorosis before the disease reaches the lethal phase. Although most of the iron reserves are located in the embryo, to accelerate the chlorosis, the endosperm was removed, and it was observed, that the iron chlorosis appears later in maize seedlings when the endosperm is removed. The relative chlorophyll content of the first and second leaves was measured in iron efficient and iron deficient maize seedlings at different times.
The higher IAA content of tumorial plant tissues is already known. The treatment with IAA decreases the iron concentration in the shoots and in the roots of +Fe precultured plants and increases at -Fe precultured ones. The TIBA retards the shoot-to-root transport of IAA. When the seedlings were treated simultaneously with IAA and TIBA, higher iron concentrations were observed in the shoots and in the roots of corn seedlings.
We found extremely high iron concentrations in the roots of infected seedlings and, in line with this, serious damage to the roots was observed that this can be caused by the high iron content generated free radicals. The results demonstrate that IAA has a role in the shoot to root communication.