The aim of this experiment was to determine the effect of root excretions of spring cereal seedlings on seed germination of field pea and common vetch. The experiment carried out in March and April 2009 under laboratory conditions (in the IUNG laboratory) involved oat, barley, wheat, triticale, field pea and common vetch. Two concentrations of excretions were applied: I – corresponding to the effect of one cereal seedling on one legume seed, II – corresponding to the effect of five cereal seedlings on one legume seed. The effects were examined after 4 and 8 days. Root excretions applied in a lower concentration usually had no effect on the tested parameters characterizing the germination of peas and vetch seeds. However, the stimulating effect of barley excretions on the length of the pea and vetch rootlet was recorded as well as the effect of triticale on the length of rootlet and the mass and length of germ in pea. Favorable effect of triticale excretions was found both after 4 and 8 days from their application. Cereal excretions with higher concentrations, except for oat excretions, had mostly an inhibitory and in some cases even destructive effect on seed germination. No favorable effect of wheat excretions on seeds of both legume species was observed on any treatments.

In field experiment carried out in years 2003-2007 at the Research Station at Mochełek (53^o13’ N; 17^o51’ E) near Bydgoszcz on good rye complex soil, the effect of fertilisation (147 and 221 kg NPK∙ha^-1), plant protection (control – no plant protection, herbicide, herbicide + fungicide), and seeding density (400 and 600 grains∙m^-2) on the yield and grain technological quality of winter wheat cultivar Tonacja grown in short-time monoculture was estimated. Research showed that winter wheat cultivation in 3-year monoculture on light soil caused a significant decrease in its yield from 5.70 t∙ha^-1 in the first year of monoculture to 2.92 t∙ha^-1 and 1.73 t∙ha^-1, respectively, in the second and third year of continuous cultivation. Advantageous effect on the size and quality of the grain yield of winter wheat grown in monoculture was given by the application of herbicide Huzar 05 WG and an increase in the fertilisation dose of NPK. Single application of fungicide Alert 375 SC during vegetative growth and an increase in seeding density did not create such an effect.

In a field experiment in years 2007-2009 at Mochełek (53^o13’ N; 17^o51’ E) near Bydgoszcz on good rye complex soil, the effect of forecrop (spring barley, blue lupine, blue lupine + spring triticale, spring rape) and nitrogen fertilisation (40, 80, 120, and 160 kg N∙ha^-1) on the yield and grain technological quality of winter wheat cultivar Tonacja was estimated. It was stated in the research that significant elements in the agronomical practices of winter wheat grown on light soil, although affecting independently, are forecrop and nitrogen fertilisation. Grain yield and its quality on a worse stand cannot be improved by increased fertilisation. The most favourable stand for winter wield yield was blue lupine in pure sowing. Spring rape, and also a mixture of lupine with spring triticale and spring barley were worse forecrops than blue lupine. On light soil in region and years with relatively low precipitation sums during the growth period, independently of forecrop, nitrogen fertilisation above 80 kg N·ha^-1 did not increase significantly grain yield but affected positively its technological quality.

Preserving grassland biodiversity requires their proper utilization. In many cases, especially in protected areas, preserving species diversity becomes the main task of cultivation measures. The aim of this study was to compare the effect of several utilization systems of low intensity on changes in sward species composition. The experiment was carried out during 2001-2007 in the vicinity of Kraków (Bielany, 50°02’ N; 19°50’ E), on sandy soil of low fertility. Four ways of fertilization was applied. The sward was cut at two times – at the beginning of June and at the end of July. In spite of a considerable increase in yield under the influence of fertilization, no statistically significant effect of the utilization system on the number of species and Shannon-Wiener diversity index was observed. Differences in the share of the most important species (red fescue, Yorkshire fog and yarrow) were greater between particular years of the experiment than between the treatments. One of the reasons for the lack of the effect of various utilization systems on species diversity could be the impossibility of the appearance of meadow species diasporas from the neighborhood. In conclusion it was found that additional sowing of selected meadow species can be necessary for regeneration of multi-species meadow communities.

The article presents the origin and speciation of utility forms of linseed and the yield of its oil form in the world, Europe and Poland. The range of comparison was broaden to the arable land in the world and Europe. Systematic decrease in linseed growing area in the world and Europe is caused by low yielding as well as low utilization of linseed products in food industry. The level of linseed yielding in European countries is low, changeable throughout the years and difficult to define unambiguously. Low seed yielding ranges the linseed in an unfavourable position in the market. On account of the unique linseed oil composition one can expect positive results of this oil trade in the future. At present it is noticed that the demand for high quality food is increasing, where linseed oil supplementation is necessary as a source of α-linolenic acid. Such an approach may result in supplying 1 to 1.5 g of this acid in food for human per day, which is significant for nutrition and health. Prevalence and application of new possibilities of linseed production will allow an increase in arable land and productivity of linseed oil form.