An experiment was carried out in the years 2004-2007 to examine the value of post-harvest residues (including straw) of spring wheat, field pea, and spring wheat-field pea mixtures preceding winter triticale cultivation. The following parameters were determined at the first stage of the study, conducted in 2004-2006: previous crop post-harvest residues and straw weight, winter triticale grain yield and total nitrogen content in the grain. Field pea provided least residues and straw. By contrast, the spring wheat-field pea mixture with the 75 + 25% proportion of the respective components as well as spring wheat produced most straw. The post-harvest residues and straw of spring wheat-field pea mixtures contained an intermediate amount of macroelements compared with their components cultivated in pure stand. Spring wheat straw accumulated less macroelements, in particular nitrogen, calcium and magnesium, compared with the straw of both field pea and spring wheat-field pea mixtures.

The study carried out in 2005-2007 estimated the effect of the kind of previous crop (spring wheat, field pea, spring wheat-field pea mixture) and the method of previous crop biomass application in the field (post-harvest residues, post-harvest residues + straw) on the yield of winter triticale, yield structure elements and total nitrogen content in grain. Grain yield and total nitrogen content in the grain of winter triticale cultivated following field pea and spring wheat-field pea mixtures was significantly higher compared with the previous crop of spring wheat. The higher winter triticale grain yield was a result of a greater number of ears per 1 m², and of kernels per ear as well as a higher weight of 1000 kernels. An increase in the proportion of field pea in the mixture with spring wheat increased winter triticale grain yield and total nitrogen content. An application of post-harvest residues and straw of the examined previous crops significantly increased winter triticale grain yield, yield components, and total nitrogen content compared with residues alone.

In the present study, we evaluated the effects of exogenously applied 24-epibrassinolide – one of the brassinosteroids – on the seed yield, seed chemical composition (content of soluble proteins, phytoestrogens, carbohydrates, minerals) and resistance to drought of soybean cultivated in Poland (cv. Aldana and Augusta). Quantitative and qualitative analysis of brassinosteroid content was made in seeds of plants treated with 24-epibrassinolide. Experiments were performed in the field and in greenhouse. Brassinosteroid was applied via presowing seed soaking (0,25 mg·dm^-3) and spraying of plants (1 mg·dm^-3). 24-epibrassinolide affected the increase of the weight of seeds per one plant (27-73%) depending on the cultivar as well as growth conditions (occurrence or lack of drought factor at the stage of seed setting). In the seeds, 24-epibrassinolide did not change content of proteins or soluble carbohydrates, but increased phytoestrogen genistein content in cultivar Aldana and decreased level of potassium in cultivar Augusta and calcium level in cultivar Aldana. In soybean seeds, the presence of brassinolide and castasterone was found. 24-epibrassinolide applied exogenously to plants was not accumulated in newly formed seeds. In drought-stressed soybean brassinosteroid showed protective effect on net photosynthesis and photosystem II efficiency.

In the years 2008-2010 the effect of glyphosate used before harvesting of white mustard at a dose of 1.0 and 2.0 kg a.s.· ha^-1 on the value of its seeds was studied. Evaluation included: weight of one thousand seeds, uniformity, weight test, energy and germination capacity as well as the initial sprout growth. Also plant emergence from seeds planted at the depth of 2 and 4 cm was determined. The effect of glyphosate on physical parameters of seeds, as well as on germination capacity and emergence capacity depended on its dose. Applied at a dose of 2.0 kg a.s.· ha^-1 it decreased uniformity and the weight of one thousand seeds, and because of the decrease of germination capacity below 87% and emergence from depth of 2 cm, it prevents their utilization as a seed material. Decrease of emergence from greater depths as a result of application of even 1.0 kg of glyphosate per ha, decreases the risk of self-sown plants as relative weeds.

In years 2006-2009, six experiments were carried out. Their aim was the assessment of the effectiveness of herbicides used for weed control in maize at lower doses and different dates. Herbicides were applied in three variants: (1) twice on weeds at a stage no later than two proper leaves regardless of maize developmental stage, (2) in-leaf operation + on-leaf operation, (3) two on-leaf operations – at the stages of 1-3 and 4-6 maize leaves. In the research, the following active substances were used: acetochlor, dicamba, linuron, florasulam + 2.4-D, fluroxypyr, foramsulfuron + iodosulfuron, nicosulfuron, nicosulfuron + rimsulfuron, and rimsulfuron. Research showed that after the application of lower herbicide doses, there is a possibility to obtain satisfactory herbicidal effect. Limitation of weed number and weed development inhibition made it possible to obtain yields that did not differ significantly from the ones obtained after the operations with standard doses. The best component in the studied herbicide mixtures proved to be the combination of florasulam + 2.4-D. In the case of significant Chenopodium album L. infestation, fluroxypyr should not be used as a mixture component. It was also found that in the conditions of late and uneven weed emergence, the system of two operations with lower herbicide doses limited effectively maize infestation in a longer growth period.

During the research, it was assessed how water extracts from Galium aparine and Matricaria maritima subsp. inodora affect the germination energy and capacity, as well as the length of the seedling root and the first leaf of the Dankowskie Zlote cultivar of Secale cereale and of the Janko cultivar of Triticale rimpaui. The experiment was conducted under laboratory conditions, with the use of Petri dishes. The influence of three concentrations of water extracts prepared from the dry and fresh mass of the plant’s above-ground parts was examined. Petri dishes watered with distilled water constituted the control treatment. Water extracts prepared from the Matricaria maritima subsp. inodora dry and fresh mass and Galium aparine fresh mass reduced the germination capacity and energy of rye and triticale in direct proportion to the increase of concentration. Higher concentrations of water extracts reduced, to a significantly larger extent, the growth of the seedling roots of both species. Lowest-concentration water extracts from the Matricaria maritima subsp. inodora dry and fresh mass and from the Galium aparine fresh mass stimulated the growth of seedling root of the cereals under study. Higher concentrations of water extracts prepared from the Galium aparine and the Matricaria maritima subsp. inodora dry mass reduced, to a significantly larger extent, the growth of the first leaf.

In the field experiment, conducted in 2007-2010 in Mochełek (53^o13’N; 17o51’E) near Bydgoszcz on good rye complex, the effect of nitrogen fertilization (40, 80, 120, 160 kg N∙ha^-1) on the yield and grain technological quality of winter wheat cultivars Bogatka, Nutka, Kris, Tonacja was evaluated. The study found that in agricultural techniques of winter wheat on light soil, cultivar and nitrogen fertilization are elements having an independent effect. Under these soil conditions, in this region and in the years of relatively low rainfall totals during the growing season, nitrogen fertilization above 80 kg N∙ha^-1 did not significantly increase the grain yield, but positively affected its technological value. Among the compared winter wheat cultivars, Kris cultivar yielded the best. Grains of this cultivar, however, had the lowest grain technological quality.

The paper presents the results of the elemental composition of the ash produced during combustion of straw and hay. Test samples of ash were characterized by alkaline pH (pH 10.2) and a substantial overall potassium content (155,7 g∙kg^-1 K), calcium (124,0 g∙kg^-1 Ca), phosphorus (15,1 g∙kg^-1 P) and magnesium (7,3 g∙kg^-1 Mg). In addition, presence of essential micronutrients for plants was found in them (Fe > Mn > Zn > Cu). A small natural content of heavy metals (Cr > Pb > Ni > Cd > Hg) in the ash is not a contraindication for the agricultural use of ash from the plant biomass.

The aim of the research conducted in the years 2005-2006 in Chrząstowo near Nakło (53^o09’ N; 17^o35’ E) was the evaluation of the productivity and yield quality of the autumn regrowth of red fescue cultivated for seeds in conditions of diversified rates and time of nitrogen fertilization. In autumn, after collecting the seeds 20, 40 or 60 kg N·ha^-1 was applied. In spring, 40, 60, 80 kg N·ha^-1 were applied once at the time of the start of growing, but also in a divided rate 40 + 40 kg (40 kg at the basic time of early spring and 40 kg at the beginning of the stage of shooting). The level of spring nitrogen fertilization did not affect green and dry matter yield of the autumn regrowth in the first and second production year. The increase of nitrogen rate in autumn from 20 to 40 kg·ha^-1 caused the increase of green matter yield by 9-10%. Additional application of 20 kg N·ha^-1 resulted in the increase of 5.6% in the first and 13.6% in the second production year. The level of autumn nitrogen fertilization did not affect the content of crude fiber, but the increase of the rate from 40 to 60 kg·ha^-1 resulted in the increase of the total protein content by 11% in the first production year. Regardless of the time and level of nitrogen fertilization, nutritional value of the regrowth was limited by the deficiency of magnesium, calcium and phosphorus.

In the report, the influence of applied plant growth regulators and weather conditions on the colour of perennial ryegrass cultivars was shown. The results were obtained on the basis of field experiments in which four cultivars of perennial ryegrass were used: Inka, Lisuna, Sabor, Figaro. Grasses were exposed to three plant growth regulators: Moddus 250 EC, Bercema CCC, Flordimex 420 SL. The experiment was conducted in the experimental plot of the University of Natural Sciences and Humanities in Siedlce (52°10’ N; 22°17’ E) in 2003-2005. Tested cultivars of perennial ryegrass were characterized by a uniform colour, but statistically significant differences occurred between individual years of research. In the case of growth regulators, a trend related to reduction in the overall assessment of lawn colour was shown in the tested cultivars. The results obtained show that among growth regulators, Moddus had the strongest effect on the colour of the tested cultivars. It was proved that retardants applied differently affected the colour of lawns in individual months and years of the study.

The paper comprises a review of the results of studies on cereal mixtures published in 2003-2007 in the Polish scientific literature. There are presented herein the most important issues concerning yield ability, weed, pest and diseases infestation. Cereal mixtures occupy the highest area among spring cereals in Poland and grain harvested from mixtures plays an important role in production of feedstock in the country. The highest concentration of mixtures is noted in the eastern region and the lowest in the south-western part of Poland. The higher yield ability of mixtures compared to pure cereal stands is connected with complementary utilization of environmental resources in different time, space (under- or aboveground) or form (water, light, nutrients) by mixtures’ components as well as with competition, responsible for changes in proportion of components in the mixture yield. The better stability of yield is attributed to a better competition ability against weeds and lower susceptibility of mixtures to diseases compared to pure stands. Mixed stands show a better response to some agronomical factors, such as irrigation, mineral fertilization and chemical protection against pests, weeds and diseases. A higher proportion of naked forms of barley and oat in mixtures has been recommended recently. Therefore, the mixture yields are lower than those of mixtures with hulled forms but their feeding value is higher, because of a lower content of fibre and a higher content of protein and fat.