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A field experiment was carried out in the Department of Agronomy of Poznań University of Life Sciences on the fields of the Research and Education Unit in Swadzim in 2009-10. Two different genotypes of maize cultivated for grain that exhibited different aging rates were compared: ES Palazzo and ES Paroli "stay-green"-type cultivar. The dynamics of dry matter accumulation were assessed 10 times every 14 days. We found that together with the progress of vegetation, the "stay-green" hybrid accumulated a significantly greater amount of dry matter in comparison with the traditional cultivar. During the generative development, the differences in production of dry matter of a single plant between the examined cultivar types were even significantly greater. The absolute growth rate (AGR) of dry matter of a single plant, leaf blades, and grain was higher for the "stay-green" hybrid when compared to the other examined cultivar. In order to assess the amount of soil mineral nitrogen remaining after plant harvesting in the autumn, the Nmin method was used in the present research. The soil mineral nitrogen content (N-NH₄+N-NO₃) after harvesting of ES Palazzo cultivar was significantly higher in comparison with the ES Paroli "stay-green" cultivar. A higher content of both mineral nitrogen forms after plant harvesting was observed in the 0-30 cm soil layer than in the 31-60 cm soil layer, irrespective of the type of maize hybrid. The content of nitrate nitrogen N-NO₃ in the total amount of Nmin in the 0-30 cm soil layer amounted to 79.6%, while at a depth of 31-60 cm it amounted to 81.2%. The examined cultivars affected the content of potassium and magnesium in soil after harvesting. However, no significant influence of maize hybrid type on the content of phosphorus and soil pH was found. A significantly lower amount of magnesium and potassium in soil after harvesting the "stay-green" cultivar when compared to the traditional cultivar proves that the main source of accumulation of these macroelements in the stage of generative growth are soil resources. This results from demand for these elements in the stage of maximum increase in biomass of generative yield. Such behavior of "stay-green"-type plants should imply a fertilization system with slow-acting fertilizers. Lack of magnesium and potassium in soil in the period of maturation of "stay-green"-type maize may be a classical example of the law of the minimum.
Acta Agrobotanica
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1998
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tom 51
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nr 1-2
147-155
Redistribution of boron (B) within apple trees (Malus domestica Borkh.) as a result of leaf B application was examined. The experiments were carried out in a greenhouse on M.26 apple rootstock and in field conditions on five-year-old 'Elstar' and 'Szampion' apple trees grafted on M.26 rootstock. Boron was applied in a form of boric acid solution. It was found that leaf B application resulted in movement of B to leaves, flowers and apple fruits untreated with B. These results clearly showed that B was retranslocated within apple tree. The retranslocation of B within apple trees took place when leaf B applications were done both in summer and autumn. Additionally, it was observed that B from leaf application had particularly high ability of movement within plant at insufficient B content (0.2pM) in solution. Generally, these data indicated that B within apple trees was transported in phloem, however mechanism of this phenomenon has not been well known yet. Thus, leaf B application of apple trees can be more successful treatment in reduction of B deficiency in plants compared to soil B application.
As reported in the paper by Grzebisz et al. (this issue), maize crop treated foliarly with fertilizer zinc at early stages of growth produced significantly high yields. Growth analysis procedures were applied to explain various effects of fertilizer zinc on grain yield increase and zinc accumulation and redistribution among maize organs in the course of the growing season. Therefore, based on the obtained zinc uptake characteristics, two major and one minor, but time-separated hot spots of zinc accumulation by maize plants have been distinguished. The first one, as described by RUR-Zn data, extended from the BBCH7 to BBCH9 stages. The second one, as expressed by CUR-Zn data, appeared during the milk stage of kernels growth and could be decisive for kernels sink capacity for accumulating carbohydrates. A minor hot spot, which occurred at tasselling may be responsible for pollen production and activity. The first zinc hot spot has also revealed the diagnostic problem of soil and plant tests for zinc. Current tests tend to overestimate plant zinc nutritional status, and therefore need to be urgently revised. Vegetative organs such as leaves and stems were only the minor sources of zinc for developing maize kernels. During grain filling period, most zinc absorbed by maize plants originated from soil resources.
W pracy przedstawiono wyniki obliczeń statycznych zbiornika prostopadłościennego uzyskane metodą numeryczną – metodą wariacyjnego ujęcia różnic skończonych. W obliczeniach uwzględniono przestrzenny charakter pracy statycznej oraz współpracę konstrukcji z podłożem sprężystym. W dalszej części pokazano, w jaki sposób można doprowadzić do przegrupowania przemieszczeń ścian oraz momentów zginających w poszczególnych partiach zbiornika. Przedstawiono to na przykładzie zastosowania ściągu spinającego przeciwległe ściany oraz przez zastosowanie przypór podpierających dłuższe ściany w środku ich rozpiętości.
W warunkach doświadczenia wazonowego badano wpływ żywienia azotem (0; 0.25; 0.50 i 1.50 g N/wazon) na bobik odmiany Dino tj. na dynamikę przyrastania biomasy korzeni i części nadziemnej w okresie od nodulacji do pełni kwitnienia i dojrzałości pełnej oraz na akumulację i redystrybucję składników pokarmowych. Stwierdzono, że umiarkowane żywienie bobiku azotem w dawce 0.50 g N/wazon wpłynęło stymulująco na wzrost i akumulację składników pokarmowych w fazie kwitnienia. Nie stwierdzono istotnego wpływu żywienia azotem na produktywność roślin bobiku w fazie dojrzałości pełnej, z wyjątkiem wzrostu masy liści. Stosowane żywienie azotem ograniczyło redystrybucję azotu, potasu i magnezu.
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