ABSTRACT
Yellow nutsedge (Cyperus esculentus) is a cosmopolitan, tropical, subtropical plant. On the basis of Ujvarosi life-form it is a G2 perennial plant, overwintering with tubers in the soil. It occurs in all continents: along Eastern and Western coastlines of Africa and even in South-Africa, North and South America, Japan, India, Near-Eastern countries, Western, Southern and Eastern Europe. It has been spread since the 70's in Europe, but its remarkable occurrence was between 1980 and 1995 years. Nowadays it occurs in Germany, the Netherlands, Belgium, France, Portugal, Austria, Croatia, Switzerland, Italy and Hungary among the European countries. The first occurrence of C. esculentus was observed in Hungary in 1993, at the surroundings of Keszthely and H&viz towns in a maize-ecosystem (Dancza 1994). It can be presumed, that its import happened with Gladiolus tubers and seed-grain of maize. At present C. esculentus occurs in four regions and surroundings of 20 habitations of Hungary. Somogy county is the most infected area, where it occurs on 10,000 hectares. C. esculentus took the 16th place in the important order of weeds of the world in the 70's. On the basis of EPPO IAS Panel at present this weed specics is considered as one of the most harmful invasive species of the world, due to its severe economic injury. Most harmful effect of C. esculentus is expressed in spring-sown hoed cultures, mainly in maize. Beside this it also occurs in sunflower, potato and sugarbeet cultures. C. esculentus has a good competitive ability by reducing crop quality and quantity. Vegetative reproduction is dominant in spreading but its propagation by seeds is also presumed in Hungary. Cool, rainy weather favours for the vegetative reproduction, while warm, dry one for the flowering. It has a 1-1.5 mm long fruit with one seed. One clustering can contain 600 seeds. According to Lapham (1985) there are areas in Zimbabwe where one can find 100 million C. esculentus seeds in a hectare. At a 1-2% germination rate it means 1-2 millions seedlings for a hectare, therefore its generative reproduction may be also considerable. The aim of our study was to examine germination characteristics and the possibility of generative spreading of C. esculentus. Germination tests were carried out in petri dishes under laboratory conditions with different thousand grain weight seeds. Average thousand grain weight and germination percentage was 0.154 and 60%, respectively. Experiments were repeated with lower thousand grain weight seeds (0.069) on sandy soil, where lower germination rate (2%) was obtained. On the basis of these results generative propagation and spreading of C. esculentus can be easily presumed.
