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The effectiveness of perennial ryegrass plantations, and hence their profitability, depends, to a considerable extent, on the specificity of the reproduced cultivar. The most appropriate strategy for maintaining high seed yields of new grass cultivars, apart from the improvement of their fodder and lawn aspects, is to seek to obtain the highest seed yield calculated per one generative shoot. In order to increase the efficiency of perennial ryegrass seed plantation it is necessary, apart from the improvement of the seeding aspect of a given cultivar by way of breeding work, also to improve technology of their cultivation. This target can be reached by optimization of agrotechnical factors stimulating biological reproductive potentials of cultivars. Results of own studies indicate that there is an optimal state of nitrogen concentration of perennial ryegrass plants in successive growth stages, which guarantees obtaining the highest seed yields on plantations. In the case of ‘Maja’ cultivar, the content of nitrogen in leaf blades at the beginning of vegetation should amount to 47 g kg⁻¹ DM and at the car initiation - 51 g kg⁻¹ DM. in the case of ‘Anna’ the optimal concentration of nitrogen in leaf blades were 54 and 57 g kg⁻¹ DM, respectively. Another very important factor is the determination of the optimal time and method of harvest as they affect the level of losses of the produced seed yield. The optimal time of seed harvest on perennial ryegrass plantations is the drop of sugars in kernels to the level of 5% DM. The increase of yields from seed plantations of Lolium perenne is a strategic matter for Polish grass seed production, which constitutes an important segment of the domestic seed industry.
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The aim of this study is to analyse economic aspects of the utilisation of complementary seeding for the renovation of grasslands. The paper presents results of our own investigations but also uses literature data to perform appropriate calculations. It appears that complementary seeding is a method of grassland renovation recommendable from the point of view of economy since the value of the ratio of the cost of production of 1 MJ feed energy to the value of its upgrading in animal production is at the level of 1.2-1.5. In comparison with the method of conventional tillage, complementary seeding is by 54- 62% cheaper, depending on the applied technological solutions. When calculating profitability of complementary seeding in grassland renovation, it seems more rational to apply the method which - for calculation purposes - takes into consideration the duration of the effect of complementary seeding expressed by the persistence of introduced species. From the economical point of view, complementary seeding should be considered as effective if the cost of the surplus of 1 dt of dry matter, 1 MJ energy or 1 kg protein obtained in the result of complementary seeding of grassland is lower than the unit cost of production of dry matter, energy or protein from sward which was not subjected to the treatment. Renovation of grassland by overdrilling, especially when performed with the aid of special seeders which increase - in comparison with traditional methods - effectiveness of yield improvement and sward quality, allows to decrease the profitability threshold of milk production. The use of complementary seeding in pratotechnique increases economic effectiveness of feeds from grasslands and, in addition - thanks to its proecological character, barely interfering in the meadow habitat - it allows to take multifaceted economic advantage from the entire natural environment. The economical aspects of complementary seeding application in grassland renovation requires further research.
The objective of this study is a determination of quantitative and qualitative changes in sward of meadow as result of their renovation by method of conventional tillage caused by different seed rate in a period of 11-years field experiment. The paper presents results of three mixtures applied for the renovation of meadows in Bielawy in 1988. Investigations were carried out in production conditions. Current recommendations were applied in fixing the seed rate. Three different mixtures were used: A - 30 kg ha⁻¹, B - 43 kg ha⁻¹ and C - 36 kg ha⁻¹. Simultaneously, on half of the experimental areas, seeds were increased by 100% and, in this way, two experimental treatments were obtained: ,,standard sowing" and „higher density sowing" . On the basis of the obtained results it was found that the seed rate should be considered as an important but frequently underestimated factor resulting in favourable quantitative and qualitative changes in the sward of grasslands established using the method of conventional tillage. Higher seed rate lead to a better development and longer persistence of the sward, which the composition is more similar to the composition of the applied mixture. Furthermore, denser sowing, by reducing the number of gaps in the sward, restricts the appearance of species not included in the mixture, which often present serious threats to the newly sown grass species, especially in the initial stages of utilisation. Higher seed rate lead to the establishment of denser swards resulting in changes in thermal and moisture conditions of the soil favourable for the growth and development of plants. Higher yields obtained from such meadows is the outcome of better light utilisation, higher soil moisture content as well as lower soil temperature. Increased seed rate ensuring the establishment of meadows characterised by the desired fioristic composition create a sound basis which can lead to their improved persistence. There should, therefore, be a positive correlation between the seed rate and meadow persistence. It may be said that higher seed rate delaying the need for their next renovation.
Studies were conducted in production conditions on 42 plantations of Areta, Leo, Nakielska, Nimba and Reda cultivars situated in the neighbourhood of Koło in Wielkopolska (Great Poland) region. The examined plantations, similar with regard to site conditions and agronomical practices, differed with regard to the level and date of mineral fertilisation. Seed plantations of the above listed cultivars were situated on mineral soils formed from medium sand characterised by medium or low macro element content and pH ranging from 5.5-6.5. Experiments were carried out in three stages. The first stage comprised a questionnaire survey concerning information about the technology of seed production of Festuca rubra cultivars. In the second stage, empirical studies were initiated. These involved selection of representative parts of plantations of 100 m² area in four replications on which assessment of weed infestation, development of generative shoots and structure of their inflorescences was performed. The effectiveness of plantations was determined on the basis of the harvested seed crop. Results obtained in the last stage of experiments were subjected to the analysis of variance with the aim to determine significance of difference between plots. The trait correlation was measured using a correlation coefficient. Moreover, seed production profitability was analysed using the method of differential calculation. In the light of the performed investigations it was found that cultivars of Festuca rubra were characterised by a considerable diversification of their yields, development of generative shoots and structure of inflorescences. From among the examined cultivars, Leo distinguished favourably in this regard, whereas Nimba was found to exhibit negative characters in this regard. The number of developed inflorescence shoots exerts a significantly positive influence on yields of Festuca rubra plantations. This effect is most conspicuous in the case of Nakielska cultivar (r=0.779**). Furthermore, plantation yields were also affected by the number of spikelets in inflorescences as evidenced most distinetly by Leo cultivar (r=0.677*) . Within individual cultivars of Festuca rubra aconsiderable variability in plantation yields, development of generative shoots and inflorescence structure was observed. The source of this variability, when differences in the effect of site and weather conditions are ruled out, is undoubtedly fertilisation. It was demonstrated that NPK fertilisation, especially fertilisation with nitrogen applied both in autumn and early spring, exerted a strong influence on the seed yield of all the examined cultivars. The size and timing of applied fertiliser doses must be adjusted to cultivar specificity. There is a specific effect of the application timing with the nitrogen fertiliser on the development of generative shoots of Festuca rubra. Leo cultivar responds positively to increased nitrogen fertilisation in early spring, while Areta, Nakielska, Nimba and Reda cultivars prefer this fertiliser to be applied in autumn. Profitability of seed production of individual Festuca rubra cultivars depends primarily on the yield of seeds harvested from a given plantation. The highest direct surplus was recorded in the case of Leo cultivar. It has been concluded that that there are considerable possibilities of development of seed production of Festuca rubra on poor sites provided plants are satisfactorily supplied with nutrients in the form of fertilisers.
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