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Funkcje siewow mieszanych zboz w plodozmianie

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Paper presents the issues related to the function of cereal mixtures in crop rotation on the basis of recent literature review. Three types of cereal mixtures were considered: mixtures of different cereal species, mixtures of cereals with leguminous crops and mixtures of the varieties. Collected data showed that the value of the field after growing a mixture depended on the mixture composition (species and varieties) and sowing proportion. Good production results were obtained in the case of cereals- leguminous mixtures as well as cereal mixtures where the oat was one of components. Such mixtures introduced into crop rotation break the continuity of cereals and- as a consequence - attenuate the negative effects of frequent return of cereals on given field. That results from numerous positive changes in soil environment (more abundant biological life, lower concentration of toxic phenol compounds, etc.) and plant coverage (lower infestation by weeds and pathogens developing on the leaves and attacking stalk base). Three-variety mixtures of spring barley in following sovings gave relatively good results. However the inter-species mixtures consisting of barley and wheat as well as wheat and wheat-rye, gave definitely poor results.
The paper presents results of 3 years of studies (2009– 2011) on the influence of Italian ryegrass on the development of weed communities in spring barley (without chemical weeds control) cultivated after potato, spring wheat and spring barley. The reaction of spring barley to the choice of the forecrop was compared with identical plots with pure stand of that cereal where herbicides were applied for weeds control. Evaluation of infestation with weeds was conducted during barley tillering and before harvest. That evaluation considered the number and composition of weed species. During harvest, the dry mass of weeds was also considered. The results were used for determination of Shannon-Wiener diversity index and species homogeneity coefficient, Simpson’s index of dominance as well as S􀂡rensen similarity index. Spring barley weeding was significantly higher in case of cultivating it in mixed stand with Italian ryegrass (without chemical control), than in pure stand (with control). In the plots with mixed crop, lower diversity and homogeneity of weeds’ communities were recorded than in pure stand. Barley in mixed crop sown after spring barley, during both times of evaluation (spring and before harvest), increased the value of the index of dominance according to the number of species the most. As concerns the composition of species, number and biomass, the communities of pure stand and mixed crop with Italian ryegrass on the plot after potato were the most similar.
The influence of sowing method and plant density on the biomass of spring wheat and Persian clover was evaluated. In a pot experiment conducted in three series during the years 2010–2012, plants were cultivated as mixed and pure crop at higher (consistent with agronomic recommendations) and lower density, decreased by 20% compared to it. Dry mass accumulation tests for both species were conducted during the following wheat growth stages (BBCH): leaf development (12–14), tillering (21–23), stem elongation (31–32), inflorescence development (54–56), and ripening (87–89). Based on the results obtained, the biomass growth rate for both species in question was also determined. It was shown that the mass of shoots of spring wheat cultivated as mixed crop was lower than that of wheat shoots grown as pure crop during the stem elongation and ripening stages. Mixed sowing limited aboveground accumulation in the heads and grain the most and in the stems the least. During the leaf development and stem elongation stages, the wheat presented a more pronounced response to the presence of clover expressed by biomass decrease in case of the treatment with lower plant density and during ripening in the treatment with recommended plant density. In case of both sowing methods and plant densities, the mass of wheat roots was similar. Biomass accumulation in Persian clover shoots and roots in mixed sowing was lower than in pure crop during the entire growing period. The wheat limited biomass accumulation of Persian clover in inflorescences the strongest and in the roots the least. The spring wheat growth rate in both sowing methods was similar as opposed to Persian clover in the case of which a decrease in the growth rate was observed in the mixed crop during the generative development period.
In pot experiment, carried out according to the additive pattern on medium soil fertilized with standard and 50% higher dose of NPK, the effect of competitive interactions between spring wheat and spring barley was estimated on nitrogen accumulation in the above-ground mass, with the distinction of stems, leaves, and spikes. Studies included three series, which were carried out in years 2003-2004 in five periods set by the rhythm of development of barley in pure sowing, namely in phases: emergence (BBCH 10-13), tillering (23), straw shooting (32), earing (55), and ripening (87-89). In a mixture, both cereals accumulated less nitrogen in the above-ground mass than in pure sowing starting from the tillering phase until the end of growth. In wheat, the decrease to a similar degree included straws, leaves and spikes, and in barley during earing it was more clearly marked in straws and leaves, and during ripening in spikes. Doses of mineral fertilization with NPK had no effect on nitrogen accumulation by barely and wheat grown in pure and mixed sowing. Competition for nitrogen between cereals started in the tillering phase and grew until the earing phase, after which it decreased slightly. Almost in the entire period of common growth, barley demonstrated to be a stronger competitor than wheat in nitrogen gaining. On bedding richer in NPK, competitive interactions between barely and wheat were more intensive than on poorer one.
Na glebie średniej, (w latach 1982-1993), realizowano ścisłe polowe doświadczenie płodozmianowe, w którym porównywano uprawę roślin w 3 modelach specjalistycznych zmianowań pastewnych, w kombinacjach nawożonych obornikiem oraz gnojowicą. Po zakończeniu eksperymentu obszar doświadczenia obsiano rośliną testową - jęczmieniem jarym. Gatunek ten wydał najwyższy plon po kukurydzy natomiast w stanowisku po zbożu (jęczmień j.), uzyskano najniższe rezultaty. Porównanie średniego plonu na obiektach z obornikiem i gnojowicą wskazuje, iż pierwsza z form nawożenia organicznego okazała się efektywniejsza.
W ścisłym, statycznym doświadczeniu, zrealizowanym w północno-wschodniej Polsce na glebie ciężkiej oceniano wpływ stanowisk w płodozmianach z 25, 50 i 100% udziałem pszenicy na stan jej zachwaszczenia. Wykazano, iż wzrost koncentracji pszenicy z 25 do 50% nie doprowadził w fazie krzewienia do nadmiernego rozprzestrzenienia się chwastów. W monokulturze natomiast ich liczba była o ponad 60% większa. Przed zbiorem zagęszczenie i masa chwastów w płodozmianie z 50% jej udziałem w stanowisku po buraku cukrowym kształtowało się na poziomie obiektu kontrolnego, zaś po pszenicy ozimej osiągnęły wartości odpowiednio o 67 i 82% większe. Uprawa w ciągłej monokulturze skutkowała natomiast około 2-krotnym przyrostem liczebności i biomasy chwastów.
The paper presents an analysis of oats phytocenosis (the crop and weeds) treated as a competitor group as concerns the species domination developing within it. The study covered oats cultivated on plots after potatoes (in crops rotation system with 25% share of oats) and twice after oats (75% share of oats in the rotation system) during the years 1990-2000. Simpson's species domination ratio and domination structure in the association identifying groups of: dominants, subdominants, influents and accessory species, were computed and studied. Relations between the studied phytocenosis features and weather conditions and oats yield were also determined. It was shown that quantitative relations in the assessed competitor associations were characterized by high variability between years and vegetation periods while no major differences were found between positions in the crop rotation systems. The density of spring phytocenosis during 11 years of studies increased resulting from increasing numbers of weeds appearing; during the late vegetation period they changed the density of associations slightly. In the spring, the groups competitive to the group of dominants consisted usually of the crop and Thlaspi arvense as well as Chenopodium album; with the passage of years their position strengthened. The enrichment of species in phytocenosis was represented mainly by an increase in numbers of accessory species. At the end of vegetation the importance of oats as a dominant increased significantly; during some seasons Chenopodium album co-dominated, however, with the passage of years the group of subdominants grew. Domination ratios for the studied competitor groups decreased with the passage of years, parallel to decrease of oats share in them. The studied features of phytocenosis showed a stronger correlation to the passage of years than the weather development. Invasiveness of weeds increased during consecutive seasons of cultivation while it showed less correlation with the density of oats. Oats yields showed a slight decreasing trend from year to year and was highly determined by the density of the entire weeds assemblage and in the spring by density and share of dominating species.
The effects of legume-cereal mixtures are usually expressed in the yield of seeds and total protein, sometimes in the yield of straw and post-harvest residues. Species composition and proportion of components in the mixture are a factor that strongly varies it. The aim of the research was determining productivity (the yield of seeds and straw as well as of the biomass of post-harvest residues) of a mixture of field pea with spring barley on the plot after potato, spring barley and after itself. The studies were carried out based on a statistical field experiment set up on rusty-brown soil, developed from silty loamy sand, deposited on slightly loamy sand and sand. The legume-cereal mixture was cultivated in six 4-plot crop rotations with its 25- and 50% proportion. In the growing season, no chemical protection was applied against diseases and weeds, however, zoocides were used against pests. It was indicated that yield of the seed mixture was similar compared to plots with crop rotation. Selection of the forecrop also did not have an effect on the straw yield, while it significantly varied the biomass of post-harvest mixture of barley with pea. The smallest quantity of residues was found after potato, while the largest in the crop rotation with field pea. In the structure of residual biomass, roots constituted lower proportion than the aboveground parts. The total production of the biomass of legume-cereal mixture, expressed in the total aboveground and underground biomass of mixture canopy was significantly higher in the crop rotation with field pea than after potato, where there occurred a significant reduction in biomass of the aboveground vegetative part of the plant.
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