SOWING TIME INFLUENCE ON THE YIELD OF WINTER WHEAT UNDER THE CLIMATE CONDITIONS OF ZEMGALE

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1 NEZĀěU MONITORINGS ILGGADĪGAJĀ IZMĒĂINĀJUMU LAUKĀ PRIEKUěOS Piliksere D., ZariĦa L. Lauksaimniecībā tiek uzsvērta nezāĝu negatīvā loma. Tās var būtiski samazināt ražas daudzumu un kvalitāti. Lai noskaidrotu dažādu agroekoloăisko faktoru ietekmi uz nezāĝainību tīrumos, PriekuĜos (57 19 Z, A) tika uzsākts ilglaicīgs pētījums. Izmēăinājums tika ierīkots velēnu podzolētā viegla smilšmāla augsnē. NezāĜu sugu un daudzuma dati tika iegūti no laukiem piecos atšėirīgos mēslojuma fonos. Pētījuma mērėis ir parādīt ilgtermiħa (17 gadu) nezāĝu dinamiku atkarībā no mēslojuma sistēmas un arī laukauga specifikai atbilstošās augsnes apstrādes paħēmieniem klasiskajā augu sekā: mieži āboliħš/zālaugi rudzi kartupeĝi. Vismazāk nezāĝu uzskaitītas nemēslotajos lauciħos. Visvairāk nezāĝu bija lauciħos, kuros kā mēslojums lietoti kūtsmēsli. SOWING TIME INFLUENCE ON THE YIELD OF WINTER WHEAT UNDER THE CLIMATE CONDITIONS OF ZEMGALE Ruža A., Kreita D. Latvia University of Agriculture, Liela iela 2, Jelgava, Latvia, LV-3001 phone: , Abstract A 3-year field experiment was conducted at the Study and Research Farm Peterlauki on silt loam brown lessive soil. Three varieties of winter wheat (Cubus, Tarso, Zentos) in 4 sowing times with a 10-day interval from the end of August till the end of September with 3 sowing rates 300, 400, and 500 germinating seeds per m 2 with four replications were included in the experiment. Certified treated seed material was used. The depth of sowing was 3 to 4 cm. Fertilizer treatments: preplant application of P 2 O 5-60 kg ha -1, K 2 O - 90 kg ha -1, split nitrogen topdressing N 150 kg ha -1 in spring after renewal of vegetation N 90, and N 60 kg ha -1 at the beginning of stem elongation stage of plant growth. The 3-year research results indicate that all the varieties of winter wheat included in the experiment showed higher ( t ha -1 ) and more stable yields between years in treatments with sowing time performed in the second half of September, i.e. in the third and fourth sowing time. Earlier planting dates, particularly at the end of August, regardless of the sowing rate resulted in vigorous tillering, the strong outgrowing of plants and the occurrence of snow mould in spring, causing the death of plants. Winter wheat Tarso was more stable regarding sowing time but more sensitive was Cubus.The sowing rate was not the yield determinant factor. Only in late sowing (the 4 th sowing time at around September), when plants with none or extremely poor tillers were going to overwinter, increased sowing rate showed the tendency of yield increase. Key words: inter wheat, variety, sowing time, sowing rate Introduction Winter wheat is one of the most productive and significant cereal species in Latvia used for food grain production. For that reason, the average grain productivity level in Latvia and grain supply both for food and feed is greatly dependent on the grain yield of winter wheat and yield stability between years. As known, the grain yield and quality of winter wheat are dependent on corresponding agro-technical measures - complex provided for a variety grown in a definite region under variable meteorological conditions. Optimal sowing time and a corresponding sowing rate have a significant role in common agro-technical measures complex to establish in autumn a healthy sward capable of wintering under inconsistent winter conditions. Current assumptions regarding sowing time and sowing rate under conditions of Latvia are based mainly on research results obtained in 70ies-80ies of the last century (Adamovičs, 1978; Bonāts and SīviĦš, 1987; Sēklkopja rokasgrāmata., 1967). As recommended in books (Jurševskis, 1988; Grīnblats, 1985) and 271

2 fixed in normative documents (Metodika, 2003), September 1 15 is the optimal sowing time for winter wheat in Zemgale and Kurzeme regions, but August 25 September 10 in Vidzeme and Latgale regions with sowing rates germinating seeds per 1 m -2. Recently, using original breeding methods, new winter wheat varieties characterized by different growth and development indices have been developed and offered to the food industry. Serious climatic changes observed in nature significantly influence the growth, development and productivity of field crops, and particularly winter crops (winter wheat) (Harrison and Butterfield, 1996; Olsen et al, 2000). Recently, climatic changes have resulted in a prolonged vegetation period of winter crops in autumn which is directly related with the probable sowing time. Recent research, which was mainly devoted to yield quality problems, proved that high grain yields with corresponding food grain quality are possible under conditions of Latvia when corresponding agro-technical measures are used. Yet frequently problems were caused by the inadequate winter-hardiness of plants under the influence of variable meteorological conditions during wintering. The winter-hardiness of wheat sowing is known to be dependent on the sowing status prior to wintering and varietal ability to adapt to variable climatic conditions and inconsistent meteorological situations during wintering. Winter wheat sward of optimal density and not outgrown is a precondition to good winterhardiness. We can obtain such a sward by choosing the proper sowing time and the number of germinating seeds per unit area suited to a variety. Research results on the time and rate of sowing winter wheat as reported by researchers in other countries (Knapowski and Ralcewicz 2004; Lupu, 2001) are not suited to Latvia and Zemgale due to different climatic conditions. Therefore the goal of this research was to come to new conclusions regarding responses to different sowing times and sward density shown by winter wheat varieties of different origin under field conditions in Zemgale. Materials and Methods Field experiments were conducted at the Study and Research Farm Peterlauki on silt loam brown lessive soil (sod calcareous). Three varieties of winter wheat (Cubus, Tarso, Zentos) in 4 sowing times with a 10-day interval from the end of August till the end of September with 3 sowing rates 300, 400, and 500 germinating seeds per m 2 with four replications were included in the experiment. In total, 36 treatments were included in the experiment. Certified treated seed material was used. The depth of sowing was 3 to 4 cm. Fertilizer treatments: pre-plant application of P 2 O 5-60 kg ha -1, K 2 O - 90 kg ha -1, split nitrogen topdressing N 150 kg ha -1 in spring after renewal of vegetation N 90, and N 60 kg ha -1 at the beginning of stem elongation stage of plant growth. Grain was harvested at the ripening stage from each replication separately. The harvested grain was weighed, and moisture content and grain purity were determined. Yield data were expressed at 100% purity and 14% moisture. Three-factor analysis of variance was used to determine yield significance level. Variation coefficients were calculated between years for each factor. Results and Discussion The average 3-year research results indicate that a comparatively high yield of winter wheat 8.49 t ha -1 was obtained. Estimates of the obtained grain yields depending on studied factors show, that different varieties of winter wheat had different responses to sowing time. All investigated winter wheat varieties sown in late August produced significantly lower grain yields compare to later sowing times. The winter wheat variety Cubus turned out to be most sensitive to early sowing. For this variety, the 3-year average grain yield obtained in the 1st sowing time was 17% lower compare to the 2nd sowing time (Fig. 1). Vigorous tillering and the strong outgrowing of plants were observed in the variety Cubus during the comparatively long after-sowing period till the end of autumn vegetation. In autumn 2006, the length of plant leaves for this variety reached even cm as a result of which a strange fact was observed when plants already in autumn were in lodging. Regardless of the sowing rate, such thickened and outgrown sowings being the result of tillering frequently suffered from snow mould which caused the death of plants. As regards sowing time, the winter wheat variety Cubus proved to be most unstable between the years. Other varieties of winter wheat also showed significant grain yield increase, yet considerably lower 10 12% compare to the 1st sowing time. Winter wheat Tarso was less sensitive to sowing time, except early sowing. Grain yield was greatest with the variety Zentos, attained in the 3rd and 4th sowing time, 272

3 i.e. in the third decade of September (beginning and end). On the whole, all winter wheat varieties included in the experiment produced higher ( t ha -1 ) and between years more stable yields of grain in treatments the sowing time of which was the second half of September the 3rd and 4th sowing time. Regarding sowing time, more stable was Tarso but expressed sensitivity was observed in Cubus. Grain yield, t ha -1 9,5 9,0 8,5 8,0 7,5 7,0 6,5 6,0 5,5 5,0 Cubus Tarso Zentos mean Sowing times Figure 1. Effect of sowing time on grain yield of winter wheat varieties The influence of sowing rate on grain yield of winter wheat on average in three years was greatly due to peculiarities of the variety. An increased sowing rate above 300 germinating seeds resulted in the tendency of yield decrease in winter wheat Cubus but yield increase in Tarso (Fig. 2). However these are comparatively insignificant sowing time yield differences. Grain yield, t ha -1 9,5 9,0 8,5 8,0 7,5 7,0 6,5 6,0 5,5 5, Cubus Tarso Zentos mean Figure 2. Effect of sowing rates on productivity of winter wheat varieties In early sowing time, the highest grain yield of winter wheat was reached with the variety Cubus using a sowing rate of 300 germinating seeds per 1 m -2. An increased sowing rate up to 400 or 500 germinating seeds resulted in significant grain yield decrease (Table 1). A similar situation was also observed in the 2nd sowing time. In the 3rd sowing time the grain yield practically did not change under the influence of the sowing rate, and only in the 4th sowing time the increased sowing rate showed the tendency of yield increase. Grain yield fluctuations in the winter wheat varieties Tarso and Zentos under the influence of sowing rates in most cases were within the limit of error. Only in late sowing (4th sowing time around September), when plants with none or extremely poor tillers were going to winter on increased sowing rate showed the tendency of yield increase. On the whole, the sowing rate is not a yield determining factor as shown by yield indices for the three experiment years. 273

4 Table 1 Grain yield on the three-year average, t ha -1 Time of sowing (A) Variety Rate of sowing (C) (B) Mean Cubus 7,85 6,65 6,61 7,04 Tarso 7,88 8,05 8,46 8,13 1st sowing time Zentos 7,54 7,97 7,88 7,80 Mean 7,76 7,56 7,65 7,66 Cubus 8,80 8,15 8,45 8,47 Tarso 8,80 9,42 9,19 9,14 2nd sowing time Zentos 8,13 8,77 8,65 8,52 Mean 8,58 8,78 8,76 8,71 Cubus 7,79 7,67 7,69 7,71 Tarso 8,92 9,18 9,38 9,16 3rd sowing time Zentos 8,94 9,11 9,04 9,03 Mean 8,55 8,65 8,70 8,64 Cubus 8,41 8,60 9,08 8,70 Tarso 8,53 9,18 9,52 9,08 4th sowing time Zentos 8,94 9,09 9,19 9,07 Mean 8,63 8,96 9,26 8,95 Mean sowing rate 8,38 8,49 8,60 8,49 Factor: A γ 0,05 = 0,417, Interaction: AB γ 0,05 = 0,66; B γ 0,05 = 0,366 AC γ 0,05 = 0,72; C γ 0,05 = 0,370 BC γ 0,05 = 0,589 The 3-year averages of yield indices practically smooth over annual deviations caused by variable meteorological conditions. Under different meteorological conditions the expression of some yield affecting factors is also different as indicated by yield variation coefficients (Table 2). Table 2 Coefficients of variation, % Factor Year 2005 Year 2006 Year st sowing time 7,25 7,70 16,06 2nd sowing time 8,95 x 11,04 3rd sowing time 7,34 7,82 3,65 4th sowing time 11,80 8,30 2,73 Cubus 10,65 7,59 x Zentos 12,76 5,21 7,44 Tarso 7,50 4,69 14, ,39 7,11 14, ,05 9,35 11, ,76 7,46 12,13 Among sowing time between years, the smallest fluctuations in the coefficient of variation - below 8% were observed for the 3rd sowing time (around 20 September). For the rest of sowing time, fluctuations in coefficients of variation between years were considerably greater, particularly in the 1st sowing time. When estimating between separate years, the influence of other factors was different in various sowing times. So in 2005, the coefficient of variation was highest in the 4th sowing time when grain yield differences under the influence of variety and sowing rates were strongly expressed compare to other sowing times. In 2006, variation coefficients are equal for all sowing times. Yet in 2007, in the 1st and 2nd sowing time the grain yield of winter wheat was considerably influenced by the variety and sowing rate, but in the 3rd and 4th sowing time the influence of the mentioned factors was comparatively small the variation coefficient was below 4%. 274

5 The influence of studied factors on grain yield indices of separate winter wheat varieties is greatly due to the meteorological situation of the year. In 2005, the time and rate of sowing had the least effect on the productivity level of the variety Tarso (variation coefficient 7.50) but Zentos was most sensitive (variation coefficient 12.76). In 2007, the situation between these varieties was entirely contrary. Variation coefficients between sowing rates within one year are characterized by weakly expressed fluctuations. Coefficients of variation were highest in % and lowest in %. The sowing rate of 400 germinating seeds per 1m -2 were more stable between years with the range of fluctuations in variation coefficients from 9.35 to %. Conclusion The 3-year research results indicate that all winter wheat varieties included in the experiment showed higher grain yields ( t ha -1 ) and were more stable between years in treatments the sowing time of which was the second half of September the 3rd and 4th sowing time. Sown earlier, particularly in late August, plants of winter wheat strongly tillered and outgrew regardless of the sowing rate. Snow mould occurring in spring caused the death of most plants. The variety of winter wheat Tarso was more stable to sowing time but Cubus was more sensitive. Sowing rate was not the factor determining yield. Only in late sowing (the 4th sowing time around September), when plants with no or very weak tillers were going to winter, increased sowing rates showed a tendency of yield increase. References 1. Adamovičs A. (1978) Formirovanie urožaja ozimoj pšenici v zavisimosti ot agroprijomov v uslovijah Latvijskoi SSR./ Dissertacija. Jelgava Augkopība (1985) / G. Grīnblata redakcijā, R. Zvaigzne Bonāts I., SīviĦš O. (1987) Intensīvā tehnoloăija graudaugu audzēšanā./ Intensīvās tehnoloăijas augkopībā. R, Avots, Jurševskis L., Holms I., Freimanis P. (1988) Augkopība. R., Zvaigzne Knapowski T., Ralcewicz M. (2004) Evaluation of Qualitative features of mikon cultivar winter wheat grain and flour depending on selected agronomic faktors. Elektronic Journal of Polish Agricultural Universities, 7, 1, Harrison P. A., Butterfield R. E. (1996) Effect of climate change on Europe - wide winter wheat and sunflower produktivity. Climate Research, 7, Lupu C. (2001) Research regarding winter wheat sowing time under conditionsof Moldavian Central Plateau. Romanian Agricultural Research, 16, Metodika labību šėirħu saimniecisko īpašību novērtēšanai (2003) Rīga, , Olsen j., Jensen T., Petersen J. (2000) Sensitivity of field-scale winter wheat production in Denmark to climate variability and climate change. Climate Research, 15, Sēklkopja rokasgrāmata (1967) R., Liesma SĒJAS LAIKA IETEKME UZ ZIEMAS KVIEŠU RAŽU ZEMGALES APSTĀKěOS Ruža A., Kreita D. Mācību un pētījumu saimniecībā Pēterlauki putekĝaina smilšmāla lesivētā brūnaugsnē tika veikts trīs-gadu izmēăinājums. Izmēăinājumā tika iekĝautas trīs ziemas kviešu šėirnes (Cubus, Tarso, Zentos), sētas četros atkārtojumos, četros sējas laikos (ar 10-dienu intervālu no augusta beigām līdz septembra beigām), ar trīs izsējas normām 300, 400 un 500 dīgstošas sēklas uz m 2. Tika izmantota sertificēta sēkla. Sēšanas dziĝums bija 3 līdz 4 cm. Mēslojums: pirmssējas P 2 O 5-60 kg ha -1, K 2 O - 90 kg ha -1, slāpekĝa virsmēslojums N 150 kg ha -1 pa daĝām pavasarī pēc veăetācijas atjaunošanās N 90 kg ha -1, un stiebrošanas sākumā N 60 kg ha -1. Trīs-gadu pētījuma rezultāti rāda, ka visām izmēăinājumā iekĝautajām ziemas kviešu šėirnēm augstākas ( t ha -1 ) un noturīgākas ražas bija sējot septembra otrajā pusē, t.i. trešajā un ceturtajā sējas laikā. Agrākie sējas datumi, īpaši augusta beigās, neskatoties uz izsējas normu, veicināja spēcīgu asnu dzīšanu, stipru augu pāraugšanu un sniega pelējuma parādīšanos pavasarī, izraisot augu bojāeju. Ziemas kvieši Tarso bija noturīgākie attiecībā uz sējas laiku, bet jutīgākie bija Cubus. Izsējas norma nebija ražu noteicošs faktors. Tikai vēlā sējā (ceturtajā sējas laikā ap

6 30. septembri), kad augi pārziemoja bez vai ar Ĝoti vājiem dzinumiem, palielināta izsējas norma uzrādīja ražas pieauguma tendenci. THE PRODUCTIVITY AND PERSISTENCY OF PURE AND MIXED FORAGE LEGUME SWARDS Slepetys J. Lithuanian Institute Agriculture, LT , Akademija, Kedainiai distr., Lithuania, phone Abstract The objective of this research was to study long - yielding legume species grown in a pure stand and in a mixture with other legumes and grasses in an organic crop rotation. The experiments were conducted during the period The swards were cut two and three times during the growing season and were used for five years in total. The highest dry matter yield of swards was produced and the largest amount of metabolisable energy in herbage was accumulated in the third year of use. Pure sainfoin (Onobrychis viciifolia) and lucerne (Medicago sativa) produced t ha - ¹ of the dry matter. Legume swards in the exceptionally dry fifth year of use produced up to 4.09 t ha - ¹ dry matter. The best yielding was mixed sward composed of fodder galega (Galega orientalis), lucerne and Festulolium. In the fifth year of use the sward of pure sanfoin produced a higher dry matter yield than pure fodder galega and pure lucerne. The sown legumes persisted well in the swards. In the fifth year of use they accounted for % of the dry matter yield. However, there was little left of Festulolium only 1-2%. When the swards were cut two or three times, a similar herbage yield was produced, however when cut more frequently the swards thinned out more severely and there was a higher infestation of forbs of which Taraxacum officinale prevailed. Lucerne responded more sensitively to more frequent cutting. Key words: legumes, swards, forage production, organic farming Introduction In Lithuania, the area of land under certified organic production is rapidly increasing. The growing interest in organic farming has also increased the role of legumes in forage production. Red clover and white clover are the most important legumes in Lithuania (Arlauskien, Maikšt nien, 2001). The economic and ecological benefits of forage legumes are well known. Biological nitrogen accumulated by legumes can be useful in various ways: it produces protein rich forage and completes the nutrient balance in soils (Sprent and Mannetje, 1996; Baležentien et al., 2000; Ledgard, 2001). However, some legumes also have undesirable characteristics, one of which is their short persistence in swards (Frame et al., 1998). Early red clover, which is the most common legume in Lithuania, yields well only in the first second years of use. In the third year, it often disappears completely. In Lithuania, fodder galega is the most long lived legume exhibiting the best overwinter survival (Baležentien et al., 2000). On an organic farm where no mineral nitrogen is applied it is very important that legumes persist as long as possible in the swards, therefore it is necessary to look for more long lived legumes that could at least partly replace red clover (Spruogis, 1999)). For the study we selected a mixture of legumes, less commonly used than clover: common sainfoin (Onobrychis viciifolia), fodder galega (Galega orientalis) and lucerne ( Medicago sativa). The objective of our tests was to study the productivity and persistence of more long lived legume species on an organic farm in a pure crop and in mixtures with other legumes and grasses under an extensive (2-3 cuts) management regime. Materials and Methods Field experiments were carried out on a sod gleyic loamy soil (Cambisol) in the central part of Lithuania (55º 23' N, 23º 51' E, with a mean annual rainfall of about 600 mm, a mean temperature of 6º C, a growing season of days. The soil characteristics were as follows: ph KCl 7.0, 276