DIVERSITY OF WEED INFESTATION DEPENDING ON MAIZE CROPPING SYSTEM

Acta Sci. Pol., Agricultura 10(1) 2011, 13-23 DIVERSITY OF WEED INFESTATION DEPENDING ON MAIZE CROPPING SYSTEM Hanna Gołębiowska Institute of Soil Science and Plant Cultivation National Research Institute in Puławy 1 Abstract. The research conducted in 2002-2008 at the Institute of Herbology and Cultivation Techniques IUNG PIB in Wrocław, in the western region of Poland (51 o 07 N; 17 o 02 E), assessed the effect of the cropping system on species diversity in field weed communities of maize grown in the crop rotation and in the monoculture. Changes in weed infestation were evaluated on the basis of phytosociological records taken in two systems of soil tillage traditional (ploughing plus cultivating measures) and nonploughing consisting of tillage with a cultivator and seedbed preparing with a combination tillage tools. After two phases of the crop rotation, the highest biodiversity of field flora was reported in maize grown according to the conventional method, with the use of ploughing, while the lowest weed infestation level occurred in monoculture with the use of reduced system. Both in growing in the crop rotation and monoculture, after introduction of reductions in cultivation there was observed the occurrence of perennial species of Elymus repens, Cirsium arvense and Equisetum arvense, as well as an increased amount of Artemisia vulgaris. Key words: biodiversity indices, field flora, maize monoculture, no-ploughing system, Zea mays INTRODUCTION Modern technologies of maize cropping contribute to an increase in yield and the improvement of quality indices, but they also create favorable conditions for the growth and development of field weeds organisms with large abilities of propagation, easily adapting to changing environment. In recent years, in order to obtain economic benefits, traditional crop rotation is more and more often abandoned for growing in monoculture and no-ploughing methods of soil tillage are used to a larger extent. In this situation, one must expect constant changes in quantitative and qualitative composition of weed Corresponding author Adres do korespondencji: dr Hanna Gołębiowska, Department of Herbology and Soil Tillage Techniques of Institute of Soil Science and Plant Cultivation National Research Institute in Puławy, Czartoryskich 8, 24-100 Puławy, e-mail: h.golebiowska@iung.wroclaw.pl

14 H. Gołębiowska communities, a growth in their mutual competitive effect, and emerging the compensation of aggressive taxons [Domaradzki and Rola 2002]. In the times of common and necessary application of herbicides, diminishing of field crops communities must occur and a new state of balance must be created in them [Czarnecka 1997, Holst et al. 2007]. However, the study by Gołębiowska [2008] indicates that reduced methods of soil cultivation by abandoning cultivation treatments create different conditions for development of weeds, and their constant diversification in communities is observed in spite of herbicidal protection. Similar tendencies were recorded in Germany, where during 40-50 years the intensity of common weeds in field crops decreased by 20-40%, whereas their floristic list is still long and undergoes constant changes under the influence of agrotechnical factors [Hurle et al. 1988]. Under conditions of reduced tillage, as compared with traditional soil cultivation, monocotyledonous species occur in larger amounts on weaker stands, particularly Echinochloa crus-galli barnyard grass and Elymus repens quack grass, and as a result of restoring fallowed lands to agricultural use, there is a growing problem with control of Artemisia vulgaris common wormwood. On more fertile black earths, in turn, under conditions of early sowing, there is a growing proportion of Galium aparine field bedstraw, Polygonum convolvulus black knotgrass, Polygonum aviculare bird s knotgrass, Veronica persica Persian speedwell and Viola arvensis field violet [Gierczyk et al. 2003, Gołębiowska 2008]. Similar studies conducted in Germany showed that under conditions of no ploughing tillage, as compared with traditional ploughing, faster spread of monocotyledonous and perennial weeds occurs, parallel to a reduction of dicotyledonous annual species [Bräutigam 1993]. It is assumed that apart from biotic and abiotic factors, agrotechnical factors have a significant effect on the state of weed infestation of a maize plantation. The aim of this study was to assess changes in field flora on the basis of biodiversity indices on plantations of maize cultivated in crop rotation and monoculture, depending on the soil cultivation system. MATERIAL AND METHODS In 2002-2008 in the Institute of Herbology and Cultivation Techniques in Wrocław, in fields belonged to the experimental Station IUNG PIB Jelcz Laskowice observations were carried out of the weed infestation of maize cultivated in the crop rotation: winter wheat + intercrop of white mustard, maize for grain, spring barley, as well as in monoculture. In both kinds of crop rotations, from 2002 two kinds of tillage systems were applied: the first the ploughing system, with ploughing using a mouldboard plough to a depth of 25 cm with seedbed preparing with traditional tools, and the other no-ploughing system, consisting of tillage with a cultivator to a depth of 12 cm with seedbed preparing with a cultivation unit. Each cultivation method was realized in a field with an area of 10 ha in the grey-brown podsolic soil formed of heavy loamy sand on light loam. Before establishing the experiments in 2002, a floristic list of weeds was made and the cover factor and phytosociological stability was determined for each species. Inspections of field weed infestation were conducted after maize emergences and before the application of herbicides. In successive crop rotations, as well as in Acta Sci. Pol.

Diversity of weed... 15 monoculture and in each cultivation variant, an approximate assessment of the degree of soil cover by the given weed species in an area of 100-200 m 2 was carried out, expressed by means of the 6-grade Braun-Blanquet scale, and a variability of weed infestation was compared with the initial state from 2002. A total of 75 phytosociological records were made on each cultivation combination in maize. The results of the study were worked out separately for crop rotation and monoculture of maize, and for ploughing and no-ploughing tillage system, determining also such elements of biodiversity as the average number of species occurring in a phytosociological record, and the total number of species. The stability of occurrence and area cover factors for all the weeds were also calculated. Monocotyledonous, dicotyledonous and other species were distinguished, and among them annual, perennial and dominating species characteristic of the tested systems of maize rotation and soil tillage. RESULTS In the years of the study, the weather conditions the air temperature and precipitation remaining at a slightly higher level than the long-term average favoured the diversity of field flora in maize. Mild winters and favorable distribution of temperatures and precipitation in the early spring allowed carrying out sowings as early as around the 10th of April and stimulated weeds for an earlier development. Some of them were developed as early as at the beginning of maize growth on treatments where no-ploughing tillage was applied, often with forms which survived the snowless winter, and the cool air in May did not threaten their development. The least favorable weather conditions occurred in 2005. A considerable water deficit occurred in the whole season, and a growth in temperature occurring at the end of June and in July resulted in the occurrence of its shortage (Table 1). Both maize cultivation in crop rotation and in monoculture with the use of ploughing and no-ploughing tillage system exerted a significant effect on its weed infestation. In 2008, in crop rotation and in the ploughing tillage system the highest count of weeds was recorded a total of 27 monocotyledonous and dicotyledonous species, including three dominating ones with the highest cover factors: barnyard grass, Chenopodium album lamb's quarters, field violet. As a result of ploughing tillage in crop rotation, the number of species in the community increased in relation to the initial state from 2002, whereas the sum of cover factors for the dominating species decreased from 8254 to 7531 (Table 2). In the years of conducting observation on the treatment cultivated with the noploughing system, the state of weed infestation remained at the similar level (Table 2). In 2008, as compared with 2002, the number of species slightly decreased. Only 19 taxons were distinguished altogether. The dominating species occurring were lamb s quarters and barnyard grass, for which considerably higher cover factors were recorded, as compared with the initial state from 2002, i.e. for barnyard grass from 3475 to 3736, and for lamb's quarters from 2796 to 3892. Apart from those species, field violet and blue cornflower occurred in quite large amounts, but with a tendency to increasing intensity. Under conditions of reduced soil cultivation, Setaria viridis green bristlegrass increased its proportion, and perennial plants also appeared, such as quack grass and field horsetail found in 40% of all the phytosociological records (Tables 2, 3). Agricultura 10(1) 2011

16 H. Gołębiowska Table 1. Monthly mean air temperature and monthly total rainfall in region of Wroclaw in comparison with many-year average (IUNG PIB Wrocław 1956-2008) Tabela 1. Średnia miesięczna temperatura powietrza oraz miesięczne sumy opadów w rejonie Wrocławia w porównaniu ze średnią wieloletnią (IUNG PIB Wrocław 1956-2008) Year Rok 1956-2006 2002 2005 2008 Weather conditions Warunki pogodowe April Kwiecień May Maj June Czerwiec July Lipiec August Sierpień September Wrzesień temperature temperatura, o C 13.4 8 13.1 15.6 18.2 17.1 13.5 8.6 rainfall opady, mm 404 37.6 61.3 71.4 80 67.7 47.6 38.4 temperature temperatura, o C 14.3 9.6 11.9 13.9 19.8 21.6 11.1 11.7 rainfall opady, mm 558.4 42.5 26.5 65.2 183.8 88.1 88.3 64 temperature temperatura, o C 14.9 10.9 13 18.2 19.8 17.2 16 9.7 rainfall opady, mm 299.6 35.6 63 71 39.9 32.1 36.5 21.5 temperature temperatura, o C 14.6 8.3 14.6 17.8 19.5 18.8 13.3 9.7 rainfall opady, mm 441.6 22.2 38.5 85.3 39.3 147.6 93.4 15.3 October Październik Acta Sci. Pol.

Diversity of weed... 17 Table 2. Selected indices of weed infestation in maize depending on different tillage systems Tabela 2. Wybrane wskaźniki bioróżnorodności zbiorowisk chwastów w różnych systemach uprawy kukurydzy Indices of weed infestation Wskaźniki bioróżnorodności zbiorowisk chwastów Crop rotation Zmianowanie Monoculture Monokultura ploughing tillage uprawa płużna no-ploughing tillage uprawa bezpłużna ploughing tillage uprawa płużna no-ploughing tillage uprawa bezpłużna 2002 2008 2002 2008 2002 2008 2002 2008 Average number of species per phytosociological record Średnia liczba gatunków w zdjęciu fitosocjologicznym 22.4 26.6 21.8 18.9 20.4 16.6 18.5 13.7 Total number of species, of which: Łączna liczba gatunków, w tym: 23 27 22 19 22 18 19 14 annual monocotyledonous jednoliścienne jednoroczne: Echinochloa crus-galli, Setaria spp 2 2 2 2 2 2 1 1 perennial monocotyledonous jednoliścienne wieloletnie: Elymus repens 0 1 1 1 1 1 annual dicotyledonous dwuliścienne jednoroczne 21 25 20 15 18 14 14 8 perennial dicotyledonous dwuliścienne wieloletnie: Artemisia vulgaris, Cirsium arvense, 1 1 2 3 Convolvulus arvense others inne wieloletnie: Equisetum arvense 1 1 1 Dominating weed species Gatunki dominujace S* W.p.** S* W.p.** S* W.p.** S* W.p.** S* W.p.** S* W.p.** S* W.p.** S* W.p.** Echinochloa crus-galli V 3735 V 3456 V 3475 V 3736 V 3938 V 4169 V 3838 V 4496 Chenopodium album V 2859 V 2753 V 2796 V 3892 V 3905 V 3806 V 4105 V 4866 Viola arvensis V 764 IV 796 V 1202 IV 944 IV 489 V 694 V 489 Centaurea cyanus V 896 IV 526 IV 1026 IV 845 V 336 V 336 Veronica persica V 325 V 773 V 325 Polygonum aviculare IV 139 Polygonum convolvulus III 178 Sum of cover factors Suma współczynników pokrycia 8254 7531 8599 8817 8993 9442 9093 9679 * S stałość fitosocjologiczna phytosociological stability ** W.p. cover factor współczynnik pokrycia Agricultura 10(1) 2011

18 H. Gołębiowska Table 3. Biodiversity of weed communities in crop rotation of maize depending on the tillage system Tabela 3. Bioróżnorodność zbiorowisk chwastów w kukurydzy w zmianowaniu w zależności od systemu uprawy roli No. Lp. Weed species Gatunek chwastu Crop rotation Zmianowanie ploughing tillage uprawa płużna no-ploughing tillage uprawa bezpłużna 2002 2008 2002 2008 1 Echinochloa crus-galli 23 V 3735 20 V 3456 21 V 3475 20 V 3736 2 Chenopodium album 25 V 2859 20 V 2753 22 V 2796 20 V 3892 3 Viola arvensis 17 V 764 19 IV 796 20 V 1202 20 IV 944 4 Centaurea cyanus 16 V 896 13 IV 526 20 IV 1026 18 IV 845 5 Veronica persica 15 IV 252 15 IV 357 20 IV 475 18 IV 325 6 Anthemis arvensis 15 IV 241 16 IV 252 15 IV 266 9 III 172 7 Papaver rhoaes 13 IV 225 15 IV 233 15 IV 225 14 IV 256 8 Solanum nigrum 16 IV 192 13 IV 195 14 IV 192 17 IV 185 9 Setaria spp. 12 IV 141 16 IV 137 12 IV 141 16 IV 315 10 Amaranthus retroflexus 15 IV 117 15 IV 125 14 IV 117 11 Matricaria inodora 16 IV 78 16 IV 75 14 IV 78 12 Aethusa cynapium 15 IV 75 13 IV 72 15 IV 75 9 III 70 13 Capsella bursa-pastoris 14 IV 60 15 IV 65 11 IV 60 9 III 68 14 Geranium pussillum 12 III 41 12 III 38 10 III 41 9 III 39 15 Stellaria media 14 III 31 11 III 34 10 III 31 8 II 17 16 Polygonum convolvulus 13 IV 28 13 IV 30 10 IV 28 10 III 23 17 Polygonum persicaria 13 IV 25 13 IV 26 12 IV 25 10 III 19 18 Fumaria officibnalis 9 III 22 11 III 23 19 Thlaspi arvense 15 III 19 12 III 18 10 III 19 20 Sinapis arvensis 6 III 15 9 III 14 8 III 15 9 III 25 21 Galinsoga parviflora 7 III 9 9 III 12 7 III 9 10 III 23 22 Euphorbia helioscopia 4 III 8 9 III 10 4 III 8 23 Tripleurospermum inodorum 3 II 3 9 II 9 24 Cerastium arvense 8 II 8 4 III 7 6 III 9 25 Veronica arvenssis 6 II 8 12 IV 176 26 Spergula arvensis 6 I 5 27 Vicia vilosa 6 I 5 28 Equisetum arvense 8 II 14 for explanations, see Table 2 objaśnienia pod tabelą 2 Acta Sci. Pol.

Diversity of weed... 19 In weed infestation of maize monoculture on treatments cultivated in ploughing and no-ploughing systems, varied intensity of two dominating species, lamb s quarters and barnyard grass, was observed. Due to reduced tillage, the cover factor for those species increased considerably in comparison with the treatment cultivated in ploughing system in crop rotation, particularly for lamb's quarters, i.e. from 2753 to 4866, namely by 76.7%. In 2002, the list of monocotyledonous and dicotyledonous weeds occurring on the treatment cultivated with the use of ploughing consisted of 18 species, whereas the phytocenosis of the later maize monoculture with reduced soil tillage was poorer and consisted of 14 species (Tables 2, 4). The frequency of occurrence and cover factors of species allow making an assessment of the factual threat to maize monoculture in the tillage systems discussed (Table 2). In the weed infestation of monoculture, the amount of dicotyledonous annual species decreased. A higher intensity of monocotyledonous annual species was also observed, as well as perennial ones, frequently or constantly present, especially in the reduced system. Apart from barnyard grass, the group of perennial weeds consisted of dicotyledonous species: common wormwood and Cirsium arvense Canadian thistle and field horsetail. The proportion of dominating species in the total area cover by weeds, particularly of lamb's quarters and barnyard grass, is worth noting. On the treatment cultivated with no-tillage system, the sum of cover factors for both species was 9362, whereas after ploughing in maize in crop rotation it amounted to 6209 (Table 2). After two crop rotations, the highest biodiversity of field flora was found in maize cultivated in the ploughing system, whereas the lowest in monoculture with the use of reductions in soil tillage. In the case of maize cultivation in monoculture after introducing cultivation reductions, the appearance of perennial species common wormwood, Canadian thistle and field horsetail was observed, as well as an increased intensity of quack grass (Table 4). DISCUSSION Maize cultivation technology, and particularly crop rotation economy, exerts a significant effect on the state and degree of weed infestation. In years it has undergone considerable reductions, in relation to expanding cereal cultivation area, including maize [Dzienia et al. 1998, Rola 1999]. Changes in maize cultivation technology were the most often forced by organizational and economic factors, such as: reductions in respect of crop rotation and soil tillage, an increase in mineral fertilization, especially with nitrogen, appearing varieties of plants well adapted to mechanical harvest, but less competitive towards weeds, supplementing the methods of agrotechnical weed control with chemical methods, which to the largest degree decided on the state and degree of weed infestation of fields [Rola and Rola 1995, Adamczewski and Dobrzański 1997]. Agricultura 10(1) 2011

20 H. Gołębiowska Table 4. Biodiversity of weed communities in monoculture of maize depending on the tillage system Tabela 4. Bioróżnorodność zbiorowisk chwastów w monokulturze kukurydzy w zależności od systemu uprawy roli No. Lp. Weed species Gatunek chwastu Monoculture Monokultura ploughing tillage uprawa płużna no-ploughing tillage uprawa bezpłużna 2002 2008 2002 2008 1 Echinochloa crus-galli 25 V 3938 20 V 4169 25 V 3838 25 V 4496 2 Chenopodium album 25 V 3905 20 V 3806 25 V 4105 25 V 4866 3 Viola arvensis 22 IV 489 19 V 694 25 V 489 20 IV 649 4 Centaurea cyanus 22 V 336 12 III 10 23 V 336 19 IV 383 5 Veronica persica 19 V 325 18 V 773 22 V 325 19 IV 498 6 Anthemis arvensis 20 IV 249 15 IV 299 17 IV 296 16 IV 357 7 Papaver rhoaes 17 IV 237 14 IV 152 12 III 236 8 Solanum nigrum 12 IV 215 9 Setaria spp. 14 IV 196 14 IV 149 10 Matricaria inodora 11 IV 115 11 Aethusa cynapium 9 IV 87 10 III 6 9 III 205 12 Capsella bursa-pastoris 8 IV 69 13 IV 65 8 II 35 15 IV 107 13 Geranium pussillum 8 III 58 12 III 27 9 III 215 14 Stellaria media 7 III 52 15 Polygonum convolvulus 13 IV 45 12 III 38 12 III 209 17 III 178 16 Polygonum aviculare 11 IV 46 14 IV 266 14 IV 311 15 IV 139 17 Polygonum persica 9 III 6 9 II 36 18 Thlaspi arvense 12 III 20 19 Sinapis arvensis 7 II 15 8 II 5 6 II 29 20 Galinsoga parviflora 9 II 7 4 I 15 21 Euphorbia helioscopia 9 II 6 14 IV 163 5 II 34 22 Artemisia vulgaris 8 II 6 10 II 11 11 III 75 16 IV 168 23 Equisetum arvense 10 III 33 12 III 32 24 Convolvulus arvense 8 II 22 25 Cirsium arvense 13 IV 45 26 Elymus repens 9 II 6 18 III 35 12 III 212 16 IV 254 for explanations, see Table 2 objaśnienia pod tabelą 2 Acta Sci. Pol.

Diversity of weed... 21 Also in the conditions of intensive farming, the traditional crop rotation is often abandoned and its filling with cereals only is observed, and maize is cultivated in monoculture. This affects changes in its weed infestation, whereas site conditions, according to Domaradzki et al. [2002] began to play a secondary role in diversification of weed communities. Any reductions in maize cultivation technology, according to Blecharczyk et al. [2004], may contribute to an increase in weed infestation in the first years of application. Favorable weather conditions in last twenty days, in comparison with the long-term averages higher temperatures, a growth in sun exposure, particularly in May and June, and precipitation remaining at the similar level, favor maize development and ripening, which in the area of Wrocław allows carrying out sowings even 10 days earlier than those recommended so far [Kozyra 2004]. The study gave attention to how different soil tillage systems: ploughing or notillage can affect the state of weed infestation of maize cultivated in the same habitat conditions. In the experiment conducted in grey-brown soil with maize cultivated in crop rotation, in a system based on ploughing, larger species biodiversity was recorded, with smaller counts than in monoculture. The list of monocotyledonous and dicotyledonous weeds found in cultivation based on ploughing was the richest, whereas in the reduced system it was poorer in species, especially in monoculture, where the fewest taxons were recorded in the community. Dominating species, irrespective of the kind of crop rotation and soil tillage system were lamb's quarters and barnyard grass. The proportion of barnyard grass in weed infestation increased particularly in monoculture and as a result of cultivation reductions, which consequently could lead to its compensation. In the structure of weed infestation of maize monoculture the number of dicotyledonous weeds decreased, particularly in comparison with conventional cultivation in crop rotation. Also a larger intensity of monocotyledonous annual and perennial species, often or constantly present, was observed, particularly in the reduced system. In the case of perennial weeds, their threat grew considerably in the no-ploughing system; beside quack grass, it was made by dicotyledonous species, such as: common wormwood, Canadian thistle and field horsetail. The results obtained confirm the thesis by Rola [1991] about a larger species abundance of weed communities in conventional cultivation using crop rotation, characterizing by a higher stability, lower threat with perennial species, which are often expansive. In such a community it is easier to control weed infestation with agrotechnical methods than in phytocenoses where one or two species predominate. CONCLUSIONS 1. Reductions in both soil tillage and crop rotation contributed to limiting species diversitiy in the phytocenosis, a considerable growth in the number of dominating species and the appearance of perennial taxons. 2. The highest species biodiversity of field weeds occurred in crop rotation and as a result of the ploughing tillage system. However, cultivation reductions resulted in a considerable increase in the proportion of green bristlegrass, and a perennial species appeared, i.e. field horsetail. Agricultura 10(1) 2011

22 H. Gołębiowska 3. In the structure of monoculture weed infestation, the amount of dicotyledonous weeds decreased and intensity of annual monocotyledonous species was observed, particularly of barnyard grass, as well as monocotyledonous and dicotyledonous perennial taxons: common wormwood, Canadian thistle and quack grass, as compared with maize grown in crop rotation, particularly using the ploughing tillage system. REFERENCES Adamczewski K., Dobrzański A., 1997. Regulowanie zachwaszczenia w integrowanych programach uprawy roślin [Regulating weed infestation in integrated programs of plant cultivation]. Prog. Plant Protection/Post. Ochr. Roślin 37(1), 58-65 [in Polish]. Blecharczyk A., Małecka I., Skrzypczak G., 2004. Wpływ uproszczonej uprawy roli na plonowanie i zachwaszczenie kukurydzy oraz na właściwości gleby [Effect of reduced tillage on yield, weed infestation of maize and soil properties]. Acta Sci. Pol., Agricultura 3(1), 157-163 [in Polish]. Bräutigam V., 1993. Einfluss verschiedener Bodenbearbeitungssysteme auf Halmbasiskrankheiten des Getreides, die Unkrautentwicklung und bekämpfung. Dissertation, Univ. Giessen. Czarnecka B., 1997. Strategie adaptacyjne roślin a skład gatunkowy fitocenoz [Plant adaptation strategies and species composition of phytocenoses]. Wiad. Bot. 41, 33-42 [in Polish]. Domaradzki K., Rola H., 2002. Wpływ długotrwałej uprawy roślin zbożowych na dynamikę zachwaszczenia pola [Effect of long-term cultivation of cereal plants on dynamics of field weed infestation]. Prog. Plant Protection/Post. Ochr. Roślin 42, 228-233 [in Polish]. Dzienia S., Piskier T., Wereszczaka J., 1998. Wpływ systemów uprawy roli na plonowanie i zachwaszczenie pszenicy ozimej [Effect of cropping systems on yielding and weed infestation of winter wheat]. Rocz. Nauk Rol. (1-2), 37-42 [in Polish]. Gierczyk T., Rola H., Domaradzki K., 2003. Wpływ technologii uprawy kukurydzy na stan zachwaszczenia i plonowania [Effect of maize cultivation technology on the state of weed infestation and yielding]. IX Międzynarodowe Symp. Ekologiczne aspekty mechanizacji produkcji roślinnej, Warszawa, 131-138 [in Polish]. Gołębiowska H., 2008. The problems of weed management by herbicide systems applied in maize. J. Plant Protect. Res. 48(1), 119-128. Holst N., Rasmussen I.A., Bastiaans L., 2007. Field weed population dynamics: a view of model approaches and applications. Weed Res. 47(1), 1-14. Hurle K., Maier J., Amann A., Weishaar T., Mozer B., Pulcher-Hausling M., 1988. Auswirkungen unterlassener Planzenschutz und Dungungsmassnahmen auf die Unkrautflora- Erste Ergebnisse aus einen mehrjahring Versuchsprogramm. Z. für Pflanzenkrankheiten und Pflanzenschutz Jurnal of Plant Diseases and Protection, SonderheftSp., XI, 175-187. Kozyra J., 2004. Climatic conditions for millet cultivation in Poland. WMO CagM Report, Geneva, 94, 34-35. Rola H., 1999. Regulacja zachwaszczenia upraw polowych w warunkach integrowanego rolnictwa [Regulation of weed infestation of field crops under conditions of integrated agriculture]. Biul. IUNG 10, 18-21 [in Polish]. Rola J., 1991. Ekologiczno-ekonomiczne podstawy chemicznej walki z chwastami na polach uprawnych [Ecological and economical grounds for chemical weed control in arable fields]. Mat. XXXI Sesji Nauk. IOR, cz. 1, 115-129 [in Polish]. Rola J., Rola H., 1995. Wpływ uproszczonej technologii uprawy kukurydzy i buraków cukrowych na stan zachwaszczenia plantacji [Effect of reduced technology of maize and sugar beet cultivation on the state of plantation weed infestation]. Mat. XXXV Sesji Nauk. IOR, cz. I, 139-146 [in Polish]. Acta Sci. Pol.

Diversity of weed... 23 RÓŻNORODNOŚĆ ZBIOROWISK CHWASTÓW KUKURYDZY W ZALEŻNOŚCI OD ZMIANOWANIA ROŚLIN I UPRAWY ROLI Streszczenie. W latach 2002-2008 w Zakładzie Herbologii i Technik Uprawy Roli IUNG PIB we Wrocławiu (51 o 07 N; 17 o 02 E) oceniano wpływ sposobu uprawy roli na zróżnicowanie gatunkowe w zbiorowiskach chwastów segetalnych kukurydzy uprawianej w zmianowaniu i monokulturze. Zmiany w zbiorowiskach chwastów oceniano metodą zdjęć fitosocjologicznych w dwóch wariantach uprawy roli: tradycyjnym (orka plus uprawki doprawiające) oraz uproszczonym składającym się z uprawy kultywatorem z doprawianiem roli agregatem uprawowym. Po przejściu dwóch rotacji w zmianowaniu największą bioróżnorodność flory segetalnej stwierdzono w kukurydzy uprawianej po zastosowaniu orki, zaś najuboższe zachwaszczenie wystąpiło w monokulturze z zastosowaniem uproszczeń uprawowych. W przypadku zmianowania, jak monokultury po wprowadzeniu uproszczeń uprawowych obserwowano pojawienie się gatunków wieloletnich Elymus repens, Cirsium arvense i Equisetum arvense oraz większą liczebność Artemisia vulgaris. Słowa kluczowe: flora segetalna, bezorkowa uprawa roli, monokultura kukurydzy, wskaźniki bioróżnorodności, Zea mays Accepted for print Zaakceptowano do druku: 28.01.2011 Agricultura 10(1) 2011