Early-maturing maize cultivars identified with index FAO 190-220 were more susceptible to damage caused by caterpillars of the European corn borer (Ostrinia nubilalis Hbn.) than medium-late maturing cultivars with index FAO 270-280. The conducted analysis of coefficients of correlation and regression demonstrated that the cultivars earliness had a significant effect on the number of caterpillars found on a plant, the percentage of damaged plants and grain yield. The increase in the FAO index was correlated with a significant decrease in the number of ECB caterpillars inside the plant (r = –0.87; p < 0.001), reduction in the number of damaged plants (r = –0.64; p < 0.001) and with an increase grain yield (r = 0.62; p < 0.001). The formulated regression equations demonstrated that the increase in the FAO index for maize cultivars by 100 units results in a decrease in the number of caterpillars in the plant, on average by 2.6 caterpillars, decrease in the number of damaged plants on average by 24.38%, and increase in the grain yield by 5.07 t·ha^-1.

In the years 2009-2011 field experiment was carried out, whose aim was determination of reaction of two white lupine cultivars to bacterial inoculation, Nitragina. It was found that the applied inoculation prolonged stages of budding and flowering by two days and the stage of maturity (technical and full) by three days compared with the control (without Nitragina). Under the effect of Nitragina, the number of pods per plant increased significantly as well as the number of seeds per pod, however the weight of 1000 seeds did not change. The result of the use of bacterial inoculation was a significant increase in the seed yield by 0.29 Mg·ha^-1, i.e. 9% compared with the control. Yields of both cultivars were high, on average 3.38 Mg^.ha^-1 in the years of research. Protein content in the dry weight of seeds increased by 2.7% after inoculation of seeds with bacteria, compared with seeds from the control. In the seeds of both cultivars total protein concentration reached a statistically similar level.

The aim of the research was comparison of the effect of tillage system (ploughing or conservation) and various catch crops and air dry matter produced by them on the level of weed infestation of spring wheat canopy cultivated after itself. The research was carried out in the years 2006-2008 on medium heavy mixed rendzina soil. The static two-factorial experiment included ploughing tillage (A) and conservation tillage with autumn disking of catch crops (B) or with their spring disking (C). At the same time, four methods of stand regeneration were applied in spring wheat monoculture in the form of various catch crops. With reference to the control plot without catch crops (a), effect of undersown catch crops of red clover (b) was compared with westerwold ryegrass (c), as well as stubble catch crops of lacy phacelia (d) and white mustard (e) on the level of weed infestation of spring wheat canopy. Conservation tillage increased species diversity of weeds in the canopy of spring wheat, their total number and air dry mass compared with the ploughing tillage. Introduction of catch crops in the spring wheat monoculture decreased species diversity in segetal flora compared with the control plot (without catch crops). Undersown catch crops of red clover and westerwold ryegrass produced a greater biomass in the evaluated 3-year period, and reduced the number of weeds to a greater extent than stubble catch crops of lacy phacelia and white mustard. Air dry mass of weeds in spring wheat cultivated after undersown catch crop of red clover was significantly lower than after undersown catch crop of westerwold ryegrass. The species that occurred in greatest numbers in the spring wheat canopy were: Galium aparine, Fallopia convolvulus and Avena fatua. Tillage system had no significant effect on the yield of dry matter of catch crop plants. Undersown catch crops reacted to changeable weather conditions to a lesser degree than stubble catch crops.

The paper presents the results of research concerning the influence of various methods of set-aside on the weed infestation of winter triticale on the light soil. In 2007-2010 the experiments were carried out in the Experimental Station in Bezek (east Lublin Region) on the podsolic soil, formed from heavy loamy sand. Triticale was sown after one-year land lying fallow, in which 5 various ways of its cultivation were used: bare fallow (mechanical), mechanical and herbicide fallow, herbicide fallow, hay-growing fallow and green fodder fallow. Roundup 360 SL was used in chemical cultivation. The range of research comprised the follow-up influence of set-aside on crop weed infestation. The infestation was defined by quantitative and weight method before triticale harvest. It was stated that the biggest number of weeds per 1 m² and their air-dry mass were observed in winter triticale sowing after hay-growing fallow. Herbicide as well as mechanical and herbicide fallow land reduced the number of perennial weeds in winter triticale canopy. The dominant species in canopy of winter triticale were monocotyledonous species, especially Apera spica-venti, Setaria pumila and Elymus repens.

Studies were conducted in years 2001-2004 at the Agricultural Experimental Station in Zawady, which is part of the Siedlce University of Natural Sciences and Humanities. The objective of the work was to analyse the effect of some characteristics of spring wheat grown in monoculture on its yield, interrupted with stubble crop growth. The effect of yield components on spring wheat yield was evaluated using the method of path analysis. It was found that, in monoculture, the yield of spring wheat grown after mustard was determined mainly by spike length, number of spikelets in the spike, mass of 1000 grains, and spike density per 1 m². The yield of spring wheat grown after phacelia was the most strongly determined by the mass of 1000 grains, number of grains per spike, and spike density per 1 m².

In the years 2005-2009 in Szelejewo (Wielkopolskie voivodeship) a field experiment was carried out, aiming at the assessment of response of seed yield and autumn regrowth green forage of three cultivars of timothy: Prosna, Obra and Nowinka to growing in two row spacings: 24 and 36 cm. The research was conducted in two series including the establishment year and two years of production. It was indicated that in the first production year the cultivars Prosna and Obra gave similar yields, whereas in the second year Prosna gave a higher seed yield. The cultivar Nowinka was characterized by the lowest productivity in growing for seeds in both production years. In the first year, the use of row spacing of 24 cm had more favourable effect on forming fertile shoots and seed yield in comparison with row spacing 36 cm. In the second year, seed yield in both row spacings was similar. In the first production year the cultivar Prosna gave the highest yields of autumn regrowth green mass, and Obra the lowest.

Studies were conducted in years 2005-2008 at the Production-Experimental Station in Bałcyny (53^o35’ N; 19^o51’ E). Research aimed at determining the effect of diversified sowing dates and densities on the yield and formation of yield components of winter triticale cultivar Moderato in the weather conditions of north-east Poland. In the described conditions, this cultivar has a very high yield potential. Average grain yield from three years was 8.91 Mg·ha^-1, and in a favourable year even 10.55 Mg·ha^-1. The highest grain yield was obtained when the sowing date was September 22^nd. Delay in the date by 10 days significantly decreased mostly the number of spikes per area. Increasing the sowing number from 300 to 500 grains per 1 m² did not diversify grain yield or any of its elements. Relation between the sowing date and density on grain yield was found but not on the particular yield components.

At the Experimental Station of the Institute of Soil Science and Plant Cultivation in Jelcz-Laskowice, the Lower Silesia, three tillage systems have been compared in field experiments carried out on lessive soil developed from heavy loamy sand since 1993. Conventional tillage – ploughing to a depth of 25-30 cm and additional cultivation of soil for sowing with the use of traditional tools; reduced tillage – with the use of a cultivator to a depth of 10-15 cm and additional tillage with a sowing set; zero-tillage – direct sowing into untilled soil. In 2006-2009 the cultivated plants included: pea, spring barley, oat and spring wheat. In spring, physical properties of soil were determined. Long-term simplifications in tillage caused slower soil warming in spring and its higher bulk density. They did not unambiguously affect soil moisture, but they influenced increase of phosphorus and potassium content in the surface layer of soil. However, long-term simplifications in tillage caused decrease in the plant yield.