ÿþ<!DOCTYPE html PUBLIC "-//w3c//dtd html 4.0 transitional//en"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <meta http-equiv="content-type" content="text/html; charset=ISO-8859-1"> <meta name="GENERATOR" content="Mozilla/4.79 [en] (Windows NT 5.0; U) [Netscape]"> <title>Abstracts Vol 6: 2</title> </head> <body> &nbsp; <br> <b><font size="+2">Agronomy Research</font></b> <blockquote><b>Volume 6</b></blockquote> <blockquote> <blockquote><b>Number 2</b></blockquote> </blockquote> <b>Abstracts</b> <br> <hr size="2" width="100%"><i>Agronomy Research</i>&nbsp; <b>6</b>(2),&nbsp;<a name="125"></a> 435&#8211;444, 2008 <br> <table border="0" cellpadding="2" cellspacing="2" width="90%"> <caption>&nbsp; <br> </caption><tbody> </tbody> <tbody> <tr> <td valign="top"> <center><span style="font-weight: bold;">Changes of nutrient concentration in chrysanthemum leaves under influence of solar radiation</span> <span style="font-size: 14pt; font-family: &quot;Times New Roman&quot;;" lang="EN-GB"></span><br> W. Bres, M. Jerzy <br> <br><br></center> <div style="text-align: justify;"><span style="font-weight: bold;">Abstract.</span> Eleven pot cultivars of the chrysanthemum (<I>Chrysanthemum</I> x <I>grandiflorum</I> /Ramat./Kitam.) were grown in 12 year-round cycles. Starting with 2 January 2002, on the second day of each successive month, rooted cuttings of all the chrysanthemum cultivars were planted into pots 14 cm in diameter, 5 cuttings per pot. From the day of potting, the plants were exposed to short-day treatment. In periods of naturally long days, the day was shortened to 10.5 hours. From November till mid-February (days under 10 hours), no supplementary assimilation light was used to improve the light conditions in the period of insolation deficit. Depending on weather conditions, the electrolytical conductivity of the nutrient solution used for plant feeding varied between 1.8 mS cm<sup>-1</sup> (in summer) and 2.2 mS cm<sup>-1</sup> (in winter). To prepare the nutrient solution rainwater was used. When 30% of inflorescences were in flower, for chemical analysis well-developed leaves from plants were sampled. The total concentrations of macro- and microelements in plant tissue were determined. To find the relationship between nutrient concentration in plant tissue and radiation, data were analysed using simple linear regression models. Radiation had an effect on nutrient concentration in chrysanthemum leaves. The highest determination coefficient R<sup>2</sup> for P and Ca, the lowest for N and K were calculated.<span style="" lang="EN-GB"> <br></div> <br> <span style="font-weight: bold;">Key words:</span> <I>Chrysanthemum</I> x <I>grandiflorum</I>, Time group, AYR, solar radiation, nutritional status of plant, statistical model<br> </span></div> </td> </tr> <tr> <td><br> </td> </tr> </tbody> </table> <hr size="2" width="100%"> <br> <i>Agronomy Research</i>&nbsp; <b>6</b>(2),&nbsp;<a name="02"></a>445&#8211;458, 2008 <center></center> <table border="0" cellpadding="2" cellspacing="2" width="90%"> <caption>&nbsp; <br> </caption><tbody> </tbody><tbody> </tbody><tbody> </tbody> <tbody> <tr> <td valign="top"> <center><b>Micropropagation of apple proliferation-resistant apomictic <I>Malus sieboldii </I>genotypes</b> <br> A. M. Ciccotti, C. Bisognin, I. Battocletti, A. Salvadori, M. Herdemertens, W. Jarausch<br> <br> </center> <div style="text-align: justify;"><span style="font-weight: bold;">Absract.</span> Apple proliferation (AP) is a serious disease of apple in Europe. Natural resistance was found in apomictic <I>Malus sieboldii</I>-derived genotypes which can be used as rootstocks and whose agronomic value is actually improved in ongoing breeding programs. As these genotypes are difficult to propagate by standard procedures micropropagation was established and validated in this study to multiply the material in larger scale. A propagation protocol was developed for <I>in vitro </I>establishment, multiplication and rooting of eleven interesting APresistant genotypes. For the optimisation of the multiplication medium, four different macro and micro element formulations were tested: MS, QL, WPM and DKW. Phytohormones (0.25 ¼M IBA, 4.44 ¼M BAP and 0.28 ¼M GA<sub>3</sub>) and vitamins (MS modified for thiamine at 2.96 ¼M), established for the propagation of M. domestica, were also suitable for the propagation of M. sieboldii-genotypes. The MS medium yielded in general the highest proliferation rates and the best shoot growth. Significantly better growth with the MS medium was also favoured by replacing Fe-EDTA by Fe-EDDHA as the iron source. By comparing four different rooting treatments a significantly higher percentage of rooting was observed when the induction was carried out in the dark with 25 ¼M IBA either in liquid or agarised medium. The time required for root formation on hormone-free medium varied among the different genotypes and three classes, low, medium and high rooting efficiency could be defined. The acclimatisation method adopted for the <I>ex vitro </I>plants in the greenhouse yielded survival rates between 90-100% for most of the genotypes. <br></div> <br> <span style="font-weight: bold;">Key words:</span> apple rootstocks, culture initiation, <I>Candidatus</I> Phytoplasma mali, <I>in vitro </I>rooting, plant tissue culture, culture media<br> </td> </tr> </tbody> </table> <hr size="2" width="100%"> <br> <i>Agronomy Research</i>&nbsp; <b>6</b>(2),&nbsp;<a name="03"></a>459&#8211;469, 2008 <br> <table border="0" cellpadding="2" cellspacing="2" width="90%"> <caption>&nbsp; <br> </caption><tbody> </tbody><tbody> </tbody><tbody> </tbody> <tbody> <tr> <td valign="top"> <div style="text-align: center;"></div> <center> <div style="text-align: center;"><span style="font-weight: bold;">The effect of sulphur fertilization on yield, quality of protein and baking properties of winter wheat</span></div> <div style="text-align: center;"><br> M. Järvan, L. Edesi, A. Adamson, L. Lukme, A. Akk<br> <br> </div> <br> <div style="text-align: justify;"><span style="font-weight: bold;">Abstract.</span> The present paper is based on the data of field and production trials conducted in the years 2004 2007. The trials were carried out in North-Estonia (59° 18 N, 24° 39 E) on breakstony soil and in South-Estonia (58° 27 N, 25° 36 E) on pseudopodzolic soil. The aim was to identify the effect of sulphur fertilization on the yield of winter wheat (<I>Triticum aestivum </I>L.) on some of the quality indices of yield and protein quality, including the content of nonreplaceable amino acids, and on the baking properties of flour. In the field trials the effect of N and NS fertilization was compared on the nitrogen background of N60 + N40 kg ha<sup>-1</sup>. Due to sulphur (in two top dressings in total S<sub>10</sub> kg ha<sup>-1</sup>) the yield of winter wheat  Lars increased, depending on the weather and soil conditions, in field trials 0.47 1.48 t ha-1, i.e. 7.7 43.0% and in production trials 1.35 2.44 t ha<sup>-1</sup>, i.e. 39.8 45.5%. The effect of sulphur on the protein and wet gluten contents of wheat grain was not always one-directional, but in all trials the gluten index increased and the quality of protein improved under the influence of sulphur. Sulphur fertilization increased the content of amino acids in the protein of winter wheat in field trials on the average as following: cysteine  24.5%, methionine  35.3%, threonine  14.4% and lysine  7.7%. In production conditions the fertilization with sulphur increased both the contents of protein and wet gluten and that of major amino acids. Due to sulphur fertilization all major parameters of winter wheat s baking quality improved: stability and quality number of dough, loaf volume and specific volume and round loaf s height to diameter ratio. <br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Key words: </span> winter wheat, sulphur fertilization, protein, amino acids, baking quality</div> </center> </td> </tr> </tbody> </table> <hr size="2" width="100%"> <br> <i>Agronomy Research</i>&nbsp; <b>6</b>(2),&nbsp;<a name="04"></a>471&#8211;476, 2008 <br> <table border="0" cellpadding="2" cellspacing="2" width="90%"> <caption>&nbsp; <br> </caption><tbody> </tbody><tbody> </tbody><tbody> </tbody> <tbody> <tr> <td valign="top"> <div style="text-align: center;"><span style="font-weight: bold;">Response of ten winter wheat cultivars to boron foliar application in a temperate climate (South-West Poland)<br> </span></div> <div style="text-align: center;">J. Korzeniowska<br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Abstract. </span> Three strict field trials were conducted in 2003, 2004 and 2006, involving foliar application of boron to ten cultivars of winter wheat commonly grown in Poland. Boron was applied as 175 g.ha<sup>-1</sup> of boracic acid. Foliar fertilization treatments caused a significant grain yield increase of four (Zyta, Kobra, Mewa and Pegassos) out of ten winter wheat cultivars. The average yield increment ranged between 9 and 15%. The cultivars which responded positively to the fertilization were the ones which produced the lowest yields on the control plots without boron. The nutritional demands of the cultivars Korweta, Kris, Soraja, Jawa, Symfonia and Sakwa for boron were much lower than those of the other cultivars. Although the foliar fertilisation with boron increased the concentration of this element in the shoots of these 6 cultivars, they did not respond with higher yield to the application of this element.<br> </div> <br> <div style="text-align: justify;"><span style="font-weight: bold;">Key words: </span> wheat varieties, B-demands and sensitivity, genotypic variation<br> </div> </td> </tr> </tbody> </table> <hr size="2" width="100%"> <br> <i>Agronomy Research</i>&nbsp; <b>6</b>(2),&nbsp;<a name="05"></a>477&#8211;488, 2008 <br> <table border="0" cellpadding="2" cellspacing="2" width="90%"> <caption>&nbsp; <br> </caption><tbody> </tbody><tbody> </tbody><tbody> </tbody> <tbody> <tr> <td valign="top"> <div style="text-align: center;"><span style="font-weight: bold;">A comparative analysis of different vegetable crops for content of manganese and molybdenum</span><br> D. Kostova, V. Kanazirska, M. Kamburova<br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Abstract.</span> The microelements manganese and molybdenum are actively absorbed by plants. The manganese and molybdenum content in 12 widely used vegetable species of the families Fabaceae, Malvaceae, Brassicaceae, Cruciferae were studied to establish the different levels of these elements in their production. Under the influence of nitrogen fertilization (400 mg N / 1000 g soil), different plant species, grown under the same soil-climatic conditions, accumulate different quantities of manganese and molybdenum from the nutrient medium. The resulting content varies considerably. Lentils are described with the highest content of manganese, 120.83 mg kg<sup>-1</sup> dry matter (family Fabaceae). The concentration of molybdenum is highest in broccoli, 29.53 mg kg<sup>-1</sup> dry matter (family Brassicaceae). Brussels sprouts and okra accumulate the least manganese and molybdenum - brussels sprouts, 5.50 mg kg<sup>-1</sup> n dry matter, >kra, 5.23 mg kg<sup>-1</sup> > dry matter. The manganese and molybdenum content in the vegetable species were determined by a new extraction-photometric method with Toluidine Blue and Tetrazolium Violet. Manganese and molybdenum has also been determined by atomic-absorption method, in order to compare the results.<br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Key words:</span> manganese, molybdenum, plants, toluidine blue, tetrazolium violet Fabaceae, Malvaceae, Brassicaceae, Cruciferae<br> </div> </td> </tr> </tbody> </table> <hr size="2" width="100%"> <br> <i>Agronomy Research</i>&nbsp; <b>6</b>(2),&nbsp;<a name="06"></a>489&#8211;498, 2008 <br> <table border="0" cellpadding="2" cellspacing="2" width="90%"> <caption>&nbsp; <br> </caption><tbody> </tbody><tbody> </tbody><tbody> </tbody> <tbody> <tr> <td valign="top"> <div style="text-align: center;"><span style="font-weight: bold;">Changes of lignin concentration and C:N in oilseed rape, wheat and clover residues during their decomposition in the soil</span><br> Z. Kriauciuniene, R. Velicka, S. Raudonius, M. Rimkeviciene<br> &nbsp; <br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Abstract.</span> Field experiments were conducted in 2003 2005 at the Experimental Station of the Lithuanian University of Agriculture to study the changes of lignin concentration and C:N in roots and top residues of winter and spring oilseed rape (<I>Brassica napus </I>L.), winter wheat (<I>Triticum aestivum </I>L.) and red clover (<I>Trifolium pratense </I>L.) after 14, 33, 63, 85 and 116 weeks of decomposition in the soil. Correlation between lignin concentration and amount of dry matter as well as the ratio of carbon and nitrogen in investigated crop residues were estimated. Investigation of crop residue decomposition during the period of 116 weeks showed that stubble and roots of winter and spring oilseed rape decompose more slowly than their threshing remains, or stubble, and roots of winter wheat and red clover. Dry matter and lignin decomposed and the ratio of carbon and nitrogen in winter oilseed rape residues decreased more slowly than that of spring oilseed rape residues. The ratio of carbon and nitrogen in the decomposing crop residues decreased most intensively during the 33 63 week period. After that, the concentration of lignin started to decrease, but its significant decline in all investigated crop residues was estimated after 116 weeks of decomposition. Lignin was most decomposed from its concentration peak in the stubble of red clover (37.9%) and least in winter oilseed rape roots (12.8%). Negative correlation between lignin concentration and dry matter amount and between lignin concentration and C:N was established in winter and spring oilseed rape, winter wheat and red clover top and root residues decomposing in the soil. <br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Key words:</span> <I>Brassica napus</I>, crop top and root residue, decomposition, dry matter, organic carbon and nitrogen ratio, lignin, <I>Triticum aestivum</I>, <I>Trifolium pratense</I>.</div> </td> </tr> </tbody> </table> <hr size="2" width="100%"> <br> <i>Agronomy Research</i>&nbsp; <b>6</b>(2),&nbsp;<a name="07"></a>499&#8211;509, 2008 <br> <table border="0" cellpadding="2" cellspacing="2" width="90%"> <caption>&nbsp; <br> </caption><tbody> </tbody><tbody> </tbody><tbody> </tbody> <tbody> <tr> <td valign="top"> <div style="text-align: center;"><span style="font-weight: bold;">Seed yield response of marvel grass (<I>Dichanthium annulatum</I>) to cutting management and nitrogen fertilisation in central India</span><br> D. Kumar, R. Seth, S. Natarajan, G.K. Dwivedi, Y.S. Shivay<br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Abstract.</span> A three-year field trial (1997 2000) was conducted to determine the most suitable cutting management practice and nitrogen level for enhanced seed production in <I>Dichanthium annulatum </I>grass under central Indian conditions. The trial was arranged in a randomized complete block design with 3 replications, comprising all combinations of 3 cutting management practices (clipping, one cut and uncut) and 4 nitrogen levels (0, 20, 40 and 60 kg N ha<sup>-1</sup>). In general, cutting and clipping did not favour seed production in marvel grass in this experiment. The uncut treatment produced significantly more seed (mean 68.6 kg ha<sup>-1</sup>) than clipping (mean 58.9 kg ha<sup>-1</sup>) and one-cut (mean 52.4 kg ha<sup>-1</sup>) treatments at all the seed harvests, except during April 1999 and April 2000. During Nov. 1997, Nov. 1998, and Nov. 1999 seed harvests, N levels 20, 40 and 60 kg ha<sup>-1</sup> did not differ significantly with respect to seed yield. However, in April 1999 and April 2000 seed harvests, the seed yield increased significantly up to 40 kg N ha<sup>-1</sup>. The average seed yields obtained during April 1999 and 2000 at 0, 20, 40 and 60 kg N ha<sup>-1</sup> were 70.7, 75.6, 84.2 and 84.9 kg ha<sup>-1</sup>, respectively.<br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Key words: </span> marvel grass, <I>Dichanthium annulatum</I>, cutting management, nitrogen fertilisation, seed yield, seed yield attributes</div> </td> </tr> </tbody> </table> <hr size="2" width="100%"> <br> <i>Agronomy Research</i>&nbsp; <b>6</b>(2),&nbsp;<a name="08"></a>511&#8211;516, 2008 <br> <table border="0" cellpadding="2" cellspacing="2" width="90%"> <caption>&nbsp; <br> </caption><tbody> </tbody><tbody> </tbody><tbody> </tbody> <tbody> <tr> <td valign="top"> <div style="text-align: center;"><span style="font-weight: bold;">Soil exhaustion and rootstock effect on the growth of apple planting material</span><br> D. Kviklys, J. Lanauskas, J. Sakalauskaite, N. Kvikliene, N. Uselis<br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Abstract.</span> Apple rootstocks P 59, P 22, P 2, P 60, M.9, M.26, MM.106, B.118 (54 118), B.396 (62 396) and  Antonowka seedlings were tested at the Lithuanian Institute of Horticulture in fresh soil and in soil previously used for an apple nursery. Replanting had a negative effect on the development of apple tree propagation material in the nursery. Bud survival of cv.  Sampion decreased by 24% compared to those in fresh soil. Other tree growth parameters were suppressed as well: tree height by 29%, trunk diameter by 24%, average leaf area by 28%, and absolutely dry leaf weight by 33%. Combining all parameters it could be concluded that apple trees of cv.  Sampion on P 59 and P 60 rootstocks are the most sensitive to soil exhaustion, whereas trees on P 2 and B.396 rootstocks show tolerance to replanting.<br> </div> &nbsp;<br> <div style="text-align: justify;"><span style="font-weight: bold;">Key words:</span> <I>Malus</I> sp., nursery, replanting, rootstock, vegetative growth</div> </td> </tr> </tbody> </table> <hr size="2" width="100%"> <br> <i>Agronomy Research</i>&nbsp; <b>6</b>(2),&nbsp;<a name="09"></a>517&#8211;529, 2008 <br> <table border="0" cellpadding="2" cellspacing="2" width="90%"> <caption>&nbsp; <br> </caption><tbody> </tbody><tbody> </tbody><tbody> </tbody> <tbody> <tr> <td valign="top"> <div style="text-align: center;"><span style="font-weight: bold;">Effect of tillage systems, mulches and nitrogen fertilization on spring barley (<I>Hordeum vulgare</I>)</span><br> I. MaBecka, A. Blecharczyk<br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Abstract.</span> Yield, N uptake, weeds and diseases of spring barley were examined under five mulching practices (white mustard, phacelia, oat-pea mixture, straw mulch, and no mulch), three tillage systems (conventional, reduced and no-tillage) and three doses of nitrogen fertilization (0, 50 and 100 kg N ha<sup>-1</sup>). In general the grain yield of spring barley for cover crops was 10-31% higher compared with the no-mulch treatment. A mulch of straw provided a smaller barley grain yield than the no-mulch treatment. Compared to conventional tillage, grain yield under reduced tillage and no-tillage were 7 and 12% less, respectively. Spring barley sowing after a mixture of oat-pea led to decreased a negative response of reduced and notillage. Grain yield after treatment with legume cover crops and without N fertilization was similar compared as the rates 50 kg N ha<sup>-1</sup> after white mustard or phacelia and as the rate 100 kg N ha<sup>-1</sup> without mulches. There was no evidence of tillage x N fertilization interaction on grain yield, dry matter production and plant-N uptake. Cover crops and straw mulch significantly decreased total weed populations compared with the treatment without mulch. Total weed density increased from 108 plants per m<sup>2</sup> in the no-tillage to 322 plants per m<sup>2</sup> for reduced tillage, and to 416 plants per m<sup>2</sup> for the conventional tillage over mulch. Higher infestation of spring barley with stem base and root diseases was observed in reduced and notillage in comparison with the conventional soil tillage and after straw mulch and no-mulch than after cover crops.<br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Key words:</span> spring barley, cover crops, tillage systems, nitrogen fertilization, grain yield, N uptake, weed and diseases infestation</div> </td> </tr> </tbody> </table> <hr size="2" width="100%"> <br> <i>Agronomy Research</i>&nbsp; <b>6</b>(2),&nbsp;<a name="10"></a>531&#8211;541, 2008 <br> <table border="0" cellpadding="2" cellspacing="2" width="90%"> <caption>&nbsp; <br> </caption><tbody> </tbody><tbody> </tbody><tbody> </tbody> <tbody> <tr> <td valign="top"> <div style="text-align: center;"><span style="font-weight: bold;">Leaf peroxidase isozyme polymorphism of wild apple</span><br> R. Petrokas, V. Stanys<br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Abstract.</span> The main aims of the study were to reveal the isozyme resemblances in the leaf peroxidase of wild apple and to define the traits related to the identification of <I>Malus sylvestris</I> Mill. The results of the study are based on leaf isozyme analysis of seven progenies selected according to the specific features of mother trees at their natural sites from the mixed forests of south-western and central Lithuania. The patterns of peroxidase isozymes were obtained by electrophoresis. The presence or absence of isoforms has been applied to compare peroxidase patterns of progenies. Species-specific peroxidase markers of <I>Malus sylvestris </I>Mill. were found. The progenies of crab apple trees had the higher proportion of identical siblings in comparison to the progenies of non-crab apple trees; autogamy or even apomixis might be the factor in wild apple if considering the resemblance of some siblings in the progenies confirmed by the simultaneous comparison of their peroxidase isozyme patterns. The phenotypic characterization of rapidly growing reproductive structures (e.g. fruit characters) may be useful for the identification of <I>Malus sylvestris </I>Mill. independent of the remaining characters of wild apple trees.<br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Key words:</span> isozyme resemblances, leaf peroxidase, <I>Malus sylvestris </I>Mill., phenotype</div> </td> </tr> </tbody> </table> <hr size="2" width="100%"> <i>Agronomy Research</i>&nbsp; <b>6</b>(2),&nbsp;<a name="11"></a>543&#8211;554, 2008 <br> <table border="0" cellpadding="2" cellspacing="2" width="90%"> <caption>&nbsp; <br> </caption><tbody> </tbody><tbody> </tbody><tbody> </tbody> <tbody> <tr> <td valign="top"> <div style="text-align: center;"><span style="font-weight: bold;">Standard and modified methods for soil organic carbon determination in agricultural soils</span><br> A. Slepetiene, J. Slepetys, I. Liaudanskiene<br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Abstract.</span> The presented study demonstrates the benefits of using modified vertical photometry methods for rapid, reliable and accurate soil organic carbon determination in agricultural soils. For tests we selected and analysed 25 arable (Ap horizon) topsoil (<I>Cambisol</I>) samples, so that the determined values cover as wide a range as possible. In the proposed method soil organic carbon is determined using 0.2 M potassium dichromate solution in diluted (1:1) sulphuric acid. The data obtained using the proposed method correlated strongly with the data obtained by <I>Vario EL </I>and titration methods. The new modification safeguards the objectivity of results, since it gives strong correlation coefficients (r = 0.989 0.990, P < 0.001, n = 25) with the dry combustion method data. The findings suggest that different photometers did not significantly affect results. However, comparison of conventional photometry and photometric determination using <I>Multiskan MS </I>equipped with the <I>Genesis Lite </I>microplate software revealed the following advantages of the latter technique: higher measurement accuracy, the facility to edit and save calibration graphs, the possibility of optimized and multiple replications, higher labour efficiency; improved safety for research personnel and lower reagent consumption. Strong and highly significant (P < 0.001) correlations were determined between the data obtained using different methods, and respective linear regression equations for the re-calculation of SOC values were developed.<br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Key words:</span> soil organic carbon, agricultural soils, determination methods</div> </td> </tr> </tbody> </table> <hr size="2" width="100%"> <br> <i>Agronomy Research</i>&nbsp; <b>6</b>(2),&nbsp;<a name="12"></a>555&#8211;561, 2008 <br> <table border="0" cellpadding="2" cellspacing="2" width="90%"> <caption>&nbsp; <br> </caption><tbody> </tbody><tbody> </tbody><tbody> </tbody> <tbody> <tr> <td valign="top"> <div style="text-align: center;"><span style="font-weight: bold;">The effect of differential nitrogen fertilization on photosynthetic pigment and carbohydrate contents in the two winter wheat varieties</span><br> T. Tranavi ien, A. Urbonavi ikt, G.Samuolien, P. Duchovskis, I. Vagusevi ien, A. Sliesaravi ius<br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Abstract.</span> The effect of nitrogen fertilizers on photosynthetic indices in two winter wheat (<I>Triticum aestivum </I>L.) varieties  Ada and  Seda was investigated in the experimental station of Lithuanian University of Agriculture during 2005 2006 and 2006 2007. The rates of fertilizers during wheat vegetation were as follows: N<sub>90</sub>, N<sub>120</sub> and N<sub>150</sub>. In sowing time both varieties were fertilized with N<sub>30</sub>P<sub>80</sub>K<sub>120</sub>. In tillering stage plants were fed with calciumammonium nitrate N<sub>60</sub> and N<sub>80</sub>. In stem elongation stage they were fertilized through leaves with carbamide solution N<sub>30</sub> and N<sub>40</sub>. Wheat photosynthetic pigment and carbohydrate contents were determined in flowering and seed growth stages. The results of analysis show that photosynthetic pigment and carbohydrate status are suitable indicators of the activity of the winter wheat photosynthetic system. Suitably selected nitrogen fertilization design may delay the natural senescence processes. However, the emergence of the indices of senescence is also dependent on environmental conditions. Nitrogen remobilization and photosynthetic activity during natural senescence is cultivar specific. The photosynthetic system of  Ada wheat variety is more sensitive to the evocative factors than  Seda wheat. The soluble sugars also participate in senescence launching: the lower hexoses/sucrose ratio corresponds to decline in photosynthetic pigment degradation. Earlier photosynthetic senescence corresponds to reduced wheat grain yields. Higher N-NH<sub>4</sub> and DOC concentrations were observed in water from the peatland. The results of these investigations showed that human activities on the farm area have a larger impact on groundwater quality than the peatland located near the farm.<br> </div> &nbsp; <br> <div style="text-align: justify;"><span style="font-weight: bold;">Key words:</span> winter wheat, photosynthetic pigments, carbohydrates, yield, nitrogen fertilization</div> </td> </tr> </tbody> </table> <hr size="2" width="100%"><i></i><br> <hr size="2" width="100%"><br> &nbsp; <br> </body> </html>