Ratarstvo ORIGINAL SCIENTIFIC PAPER

Crop sequence influence on reduction of maize weed infestation Igor Spasojević1, Milena Simić1, Dušan Kovačević2, Vesna Dragičević1, Željko Dolijanović 2, Milan Brankov3 Maize Research Institute, Zemun Polje, Slobodana Bajića 1, Belgrade-Zemun, Serbia ([email protected]) 2 University of Belgrade, Faculty of Agriculture, Nemanjina 6, Belgrade-Zemun, Serbia 3 Scholar of the Ministry of Education, Science and Technological Development of the Republic of Serbia 1

Abstract The objective of this study was to determine the changes in weed infestation of maize caused by crop sequence. The trial encompassed two types of the crop sequence: maize-soybean-wheat-maize (CS I) and maize-wheat-soybean-maize (CS II). The number of weed species as well as weed fresh biomass decreased, in the CS I, while the number of plants per weed species increased. On the other hand, in the CS II, the number of weed species and the number of plants per weed species increased, while weed fresh biomass insignificantly decreased. Crop sequencing in the crop sequence I (CS I) contributed, to greater extent, to the reduction of maize weed infestation than in the crop sequence II (CS II). Key words: maize, crop rotation, weed infestation. Introduction Weeds can significantly affect the yield reduction; hence, weed suppression is a very important cropping practice in maize cultivation. The weed infestation level of maize crop vary over regions, years and other factors (Milošev et al., 2009). Besides direct measures, the crop rotation, i.e. crop sequencing is also a very efficient preventive action. The crop rotation is defined as the planned and science-based system of growing a sequence of different crops on the same land to achieve as better as possible utilisation of the growing environment (Kovačević, 2003). Today, the crop rotation is very important cropping practice due to which optimum yields of crops are obtained without affecting the ecological balance in the environment (Pop et al., 2009). Issues related to growing systems, continuous cropping and crop rotation, due to their complexity and duration, and particularly the aspects of weed control, have been rarely included into programmes of scientific studies (Debreczeni and Korschens, 1993). In Serbia, maize is grown on a greater area than wheat, soybean and sugar beet and therefore maize is usually sown on the same land in two of more successive years (Kovačević, 2008). Such a growing system - continuous cropping causes many problems to maize producers in a way that it increases weed infestation, number of pests and diseases and reduces grain yields (Jovanović et al., 2006). If maize is grown in the crop rotation, this system is referred to as a "Balkan crop rotation", meaning a maize-what rotation (Stefanović et al., 2011). Wheat as a winter crop, suppresses the growth and development of winter, winter-spring and spring weeds. Wheat seedlings and stalks have an allelopathic effect on the development on numerous weeds (Muminović, 1991; cit. Wu, 2001). The increase of areas under soybean has led to the three crop rotation: maize-soybeanwheat. The presence of plants of the family Fabaceae significantly contributes to the efficiency of the crop rotation, because the maize yield increases, while the application of mineral nitrogen fertilisers can be reduced by even 50%, which is a significant saving and

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Field Crop Production it is important for the maintenance of soil quality (Dolijanović et al., 2011).There are two types of such three crop rotations: 1) wheat-maize-soybean and 2) soybean-maize-wheat. The first type of the crop rotation is not sufficiently efficient, because maize does not use nitrogen that remains in the soil after the cultivation of legumes. The goal of this study was to determine changes in maize (Zea mays L.) weed infestation caused by crop sequencing in both stated crop rotations. Material and methods The studies were carried out on slightly calcareous chernozem in the experimental field of the Maize Research Institute, Zemun Polje in the 2009-2012 period. Two types of the crop sequence were applied in the trial: maize-soybean-wheat-maize (crop rotation I) and maize-wheat-soybean-maize (crop rotation II) in order to monitor weed infestation in maize crops under conditions when herbicides were not applied. Crop sequencing in both crop rotations was initiated with maize in 2009. The hybrid ZP 606 was sown. An amount of 30 t manure ha-1 was applied in the crop rotation I in autumn of 2011, after wheat harvest and prior to maize sowing. On the other hand, manure was not applied in the crop rotation II, in which maize was sown after soya bean. Weeds were scored 45 days from the sowing date by the one square meter area method. The number of weed species and the number of plants per weed species (number m-2) were estimated and then weed fresh biomass (g m-2) was measured. The results obtained in 2009 and 2012 are presented in this paper, when the first rotation of maize, wheat and soybean was done and when maize was sown in both crop rotations. The obtained data were processed by the analysis of variance and LSD test. Results and discussion The application of two different three crop rotations shows the difference in maize weed infestation. The number of weed species in the crop rotation I (CS I) decreased in 2012 (15 species) in relation to 2009 (16 species), while this number in the crop rotation II (CS II) was significantly higher in 2012 (14 species) than in 2009 (12 species), when the trial was set up (Figure 1).

Number of weed species

18

LSD 0.05 = 1.791

16 14 12 10 8

2009

6

2012

4 2 0

CS I

CS II Crop sequence

Figure 1. The number of weed species Based on the number of plants per weed species and weed fresh biomass the following annual species prevailed: Chenopodium album L., Chenopodium hybridum L. and Datura stramonium L. There are great problems related to the competition for light between maize and weeds such as Chenopodium album L. that could be higher than 1 m (Lindqist et al.,

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Ratarstvo 1998). Among perennial weed species, the most dominant were Sorghum halepense Pers., Convolvulus arvensis L. and Bilderdikya convolvulus L. The most dangerous and aggressive among perennial weed species is Sorghum halepense Pers. that mainly occurs on chernozem and other soils of good quality (Kovačević, 2008). The number of plants per weed species was higher in both crop rotations in 2012 than in 2009 (Table 1). In the crop rotation I, this number increased from 61 to 86 plants m-2. The reason for this increase could be manure that was applied in autumn of 2011. According to Cook et al. (2007), the application of manure can increase weed infestation of crops. If animals have consumed weeds, weed seeds would pass through their digestive tract unharmed, and would finished off in manure. If such manure is applied, weed seeds will germinate under favourable conditions and a new weed plant will grow. In spite of the fact that manure was not applied in the crop rotation II, the number of plants per weed species increased from 59 plants m-2 in 2009 to 82 plants m-2 in 2012. Table 1. Number of plants per weed species (number of plants m-2) Weed 2009 species CS I CS II Chenopodium hybridum 12 11 Chenopodium album 7 1 Datura stramonium 9 11 Abutilon thephrasti 3 3 Solanum nigrum 2 6 Amaranthus retroflexus 2 Convolvulus arvensis 6 6 Iva xanthium 7 Stachys annua 3 3 Hibiscus trionum 1 Bilderdykia convolvulus 2 1 Sorghum halepense 1 10 Amaranthus hybridus 1 Atriplex patula 3 Reseda lutea 1 3 Ambrosia arthemisifolia 1 Amaranthus albus Xanthium sttrumarium Heliotropium europeum Sonchus arvensis Cirsium arvense 3 Panicum crus-galli 1 Total 61 LSD0,05 CS I- Crop rotation I, CS II- Crop rotation II

59

2012 CS I 17 11 5 6 12 8 2

CS II 18 10 6

8

5 1 6 16

2 5 3 1 3

6 2 4

1 5

2 1 1 1

86

82

20.94

Weed fresh biomass was smaller in both crop rotations in 2012 than in 2009 (Table 2). In crop rotations I and II weed fresh biomass decreased from 5861.6 g m-2 to 3628.5 g m-2 and from 2411.8 g m-2 to 2188.0 g m-2, respectively.

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Field Crop Production Table 2. Weed fresh biomass (g m-2) Weed 2009 species CS I Chenopodium hybridum 1502.4 Chenopodium album 910.6 Datura stramonium 604.4 Abutilon thephrasti 139.6 Solanum nigrum 70.9 Amaranthus retroflexus 223.5 Convolvulus arvensis 329.7 Iva xanthium 964.3 Stachys annua 104.8 Hibiscus trionum 10.5 Bilderdykia convolvulus 108.8 Sorghum halepense 35.5 Amaranthus hybridus 25.1 Atriplex patula 678.1 Reseda lutea 56.0 Ambrosia arthemisifolia 97.4 Amaranthus albus Xanthium strumarium Heliotropium europeum Sonchus arvensis Cirsium arvense Panicum crus-galli

2012 CS II 397.6 74.5 893.0 105.9 76.2

CS II 556.8 483.6 200.8

100.9

CS I 637.7 1290.6 386.4 75.2 241.0 208.9 13.0

81.9

210.8

112.4 261.8

26.3 82.7 192.6 80.5 110.1

62.7 12.3 337.4 239.0

96.0

26.3 11.9 34.3

128.5 88.7

23.3 49.4 1.1 4.6 59.9 151.7

Total 5861.6 2411.8 3628.5 2188.0 LSD0,05 1018.0 CS I- Crop rotation I, CS II- Crop rotation II According to obtained results it can be observed that significant decrease of weed fresh biomass was only recorded in the crop rotation I, while remaining variations were not significant. Conclusion The weed infestation level in maize crops in variants without the herbicides application decreased in the three crop rotation in which wheat was a preceding crop to maize just after one rotation. This decrease was manifested through a significant decrease of weed fresh biomass, even though the number of plants per weed species increased. In the three crop rotation without the herbicides application in which soybean was a preceding crop to maize, weed fresh biomass decreased, while the number of weed species and number of plants per weed species increased after just the first rotation. Considering such variations of certain parameters of weed infestation, it is necessary to apply the crop rotation for a longer period, because the crop rotation as a cropping practice gives the most accurate results after several rotations. Acknowledgement This study was supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia, Project TR-31037.

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Ratarstvo References Cook R. A., Posner L. J., Baldock O. J. (2007). Effects of dairy manure and weed management on weed comunities in corn on Winsconsin cash-grain farms. Weed Technology, 21: 389395. Debreczeni K., Korschens M. (2003). Long term fild experiment of the world. Archives of agronomy and soil science, 49: 465-483. Dolijanović Ž., Kovačević D., Momirović N., Oljača S., Šeremešić S, Jug D. (2011). Zakorovljenost i produktivnost useva soje u zavisnosti od sistema gajenja. InZbornik radova Međunarodnog naučnog Simpozijuma agronoma „Agrosym Jahorina 2011“, Jahorina, BiH, 10-12. novembar, 119-125; Jovanović Ž., Đalović I., Dugalić G., Kovačević V. (2006). The role of production systems and fertilization on contemporary maize growing. In Proceedings of 41st and 1st International Symposium on Agriculture, Opatija, Croatia. Kovačević D. (2003). Sistemi biljne proizvodnje. In Opšte ratarstvo, 636-650. Beograd,Srbija: Poljoprivredni fakultet. Kovačević D., Dolijanović Ž., Oljača S., Jovanović Ž. (2008). Uticaj plodoreda u borbi protiv korova. Acta herbologica, 17: 45-51: Kovačević D. (2008). Biološki aspekti mera borbe protiv korova. In Njivski korovi biologija i suzbijanje, 302-314. Beograd, Srbija: Poljoprivredni fakultet. Lindqist L. J., Mortensen A. D., Johnson E. B. (1998). Mechanisms of corn tolerance and velvetleaf suppresive ability. Agronomy journal, 90: 787-792. Milošev D., Đalović I., Knežević A., Nikolić Lj., Džigurski D., Šeremešić S., Nestorović S. (2009). Uticaj sistema obrade zemljišta i plodoreda na građu korovske zajednice useva kukuruza. Acta herbologica. Vol 18. (No. 1): 17-27. Muminović, S. (1991). Allelopathic influence of straw of crops on the germination, height and weight of weeds. Radovi Poljoprivrednog Fakultete Univerziteta u Sarajevu, 39: 29-37. Pop A. I., Gus P., Rusu T., Ileana B., Moraru P., Pop L. (2009). Influence of crop rotation upon weed development on corn, wheat and soybean crops. USAMV Bucharest: 267-272. Stefanović L., Šinžar B., Simić M. (2011). Tehnologija gajenja merkantilnog kukuruza. In Kontrola korova u agroekosistemu kukuruza, 54-58. Srbija:Društvo genetičara Srbije. Wu, H., Pratley, J., Lemerle, D. & Haig T. (2001). Allelopathy in wheat (Triticumaestivum L.). Annals of applied biology, 139: 1-9.

Utjecaj smjene usjeva na zakorovljenost kukuruza Sažetak Cilj istraživanja je bio utvrditi promjene u zakorovljenosti kukuruza uzrokovane smjenom usjeva. Pokus je obuhvaćao dva tipa plodosmjene: kukuruz-soja-pšenica-kukuruz (plodored I) i kukuruz-pšenica-soja-kukuruz (plodored II). Broj vrsta kao i svježa masa korova su se smanjili na plodoredu I, dok se broj jedinki korova povećao. Na plodoredu II broj vrsta i broj jedinki korova se povećao, dok se svježa masa korova neznatno smanjila. Način smjenjivanja usjeva u plodoredu I u većoj mjeri je doveo do smanjenja zakorovljenosti kukuruza nego redoslijed smjenjivanja usjeva u plodoredu II. Ključne riječi: kukuruz, plodored, zakorovljenost.

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