Spanish Journal of Agricultural Research 16 (4), e1009, 7 pages (2018) eISSN: 2171-9292 https://doi.org/10.5424/sjar/2018164-12531 Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, O.A, M.P. (INIA) RESEARCH ARTICLE OPEN ACCESS Effect of tillage system on the structure of weed infestation of winter wheat Andrzej Woźniak University of Life Sciences in Lublin, Dept. Herbology and Plant Cultivation Techniques, Akademicka 13, 20-950 Lublin, Poland. Abstract The study aimed to evaluate the structure of weed infestation of winter wheat grown in different weeding systems: conventional tillage (CT), reduced tillage (RT), and herbicide treatment (HT). In CT system, shallow ploughing and pre-sow ploughing were conducted after the harvest of the previous crop. In RT system, shallow ploughing was replaced by cultivator tillage, whereas pre-sow ploughing by a tillage set. In HT system, shallow ploughing was replaced by spraying with glyphosate and pre-sow ploughing by cultivator tillage. At the tillering stage (22-23 in BBCH scale), species composition and number of weeds/m2 were determined with the botanical-gravimetric method, whereas at the stage of waxy maturity of wheat (82-83 BBCH) analyses were conducted for species composition as well as density, air-dry weight, and weed distribution in crop levels. The Shannon-Wiener’s diversity index (H’) and degrees of phytosociological constancy (S) of weeds were determined as well. The study showed that more weeds occurred in RT and HT systems than in the CT system and they produced higher biomass in RT than in CT and HT systems. The tillage system affected weed distribution in crop levels. In CT system, the highest weed density was identified in the ground and lower levels, whereas in RT and HT systems in the ground and middle levels. Values of the species diversity index (H’) indicate a similar diversity of weed species composition between weeding systems and more diverse between study years. Additional keywords: species richness; air-dry weight of weeds; weed distribution in crop levels; degrees of phytosociological constancy. Abbreviations used: CT (conventional tillage); DM (dry matter); GS (growth stage); H’ (Shannon-Wiener index); HSD (honestly significant difference); HT (herbicide treatment); RT (reduced tillage); TS (tillage system). Citation: Woźniak, A. (2018). Effect of tillage system on the structure of weed infestation of winter wheat. Spanish Journal of Agricultural Research, Volume 16, Issue 4, e1009. https://doi.org/10.5424/sjar/2018164-12531 Received: 03 Nov 2017. Accepted: 13 Nov 2018. Copyright © 2018 INIA. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC-by 4.0) License. Funding: Poland’s Ministry of Science and Higher Education (part of the statutory activities of the Dept. Herbology and Plant Cultivation Techniques, University of Life Sciences in Lublin). Competing interests: The authors have declared that no competing interests exist. Correspondence should be addressed to Andrzej Woźniak: [email protected] Introduction sprouting. It results in a depletion of the seed bank in the soil and, thus, in lesser crop infestation with weeds The tillage system and improvement of agrotechnical (Riemens et al., 2007; Gruber & Claupein, 2009). In measures have a significant effect upon the condition turn, seeds with a long resting period may germinate and extent of crops infestation with weeds (Gruber et even after decades of resting in the soil (Basset & al., 2012; Nichols et al., 2015; Woźniak & Soroka, Crompton, 1975). The weeding system affects also 2017). According to Tørresen & Skuterud (2002) and to the biodiversity of weeds. Usually, the replacement Gruber & Claupein (2009), the no-till system increases of mechanical treatments by chemical ones facilitates reserves of diaspores in the topsoil, which leads to crop weed diversity decrease and compensation of herbicide- infestation with weeds (Cardina et al., 2002; Chauhan tolerant species (Wesołowski et al., 2008). As shown et al., 2006; Mohler et al., 2006; Małecka-Jankowiak by Woźniak & Soroka (2015a), the highest number et al., 2015). As reported by Hoffman et al. (1998), of weed species in pea crops occurred in the reduced Bàrberi et al. (2001) and Woźniak (2007), from 60 to tillage system with the use of a tillage unit consisting 90% of the seed bank may be deposited in the topsoil. of a cultivator and a roller, whereas the lowest number During mechanical cultivation, weed seeds with a short in the system of direct sowing. Herbicides used in the resting period are transferred from the topsoil into conservation and stubble systems eliminate perennial deeper soil layers, from where only few are capable of species and effectively reduce infestation with short- 2 Andrzej Woźniak lived species (Gruber & Claupein, 2009). Streit et al. of precipitation reach: 30 mm, 23 mm, and 26 mm, (2002) showed that for no-tillage technologies without respectively. herbicides, the weed density was lower than that in conventional or minimum tillage. In technologies with Experimental design herbicides, Ishaya et al. (2008) found converse results. The detrimental effect of weeds depends on their In this experiment, winter wheat (Triticum aestivum ability to compete with the crop. This ability depends L.) of ‘Ozon’ cultivar was sown in the following tillage likewise in their growth rate at early stages, their systems (1) conventional (CT), (2) reduced (RT), and (3) canopy, the density of the crop and also, on the number herbicide (HT). The experiment was established with the and biomass of weeds. Significant is also height of method of completely randomized blocks (8 × 75 m) in the weeds in relation to the cereal crops (Woźniak & three replications. In the CT system, shallow ploughing Soroka, 2015b). Generally, weeds of the upper level (at a depth of 10-12 cm) was applied after the harvest (in spread anemochorically, these of the middle level either August) and pre-sow ploughing (20-25 cm) in the middle fall down before harvest or are harvested with the crop, of September. In the RT system, shallow ploughing was whereas weeds of the bottom and ground levels ripen in replaced by cultivating measures (10-15 cm), while pre- the stubble field and increase the seed bank in the soil. sow ploughing by a tillage set (10-12 cm). In the HT Naturally, upper and middle level also does increase system, shallow ploughing was replaced by spraying with the seed bank in the soil by gravity or air‐transport glyphosate (Roundup 360 SL in a dose of 4 L/ha), whereas (Woźniak & Soroka, 2017). pre-sow ploughing by cultivating measures. At all plots, The study aimed to evaluate the structure of weed pea was sown as the previous crop before winter wheat. infestation – number of species, mass of weeds, species composition and species distribution in levels of Sowing, fertilization and crop protection winter wheat crop sown in conventional, reduced, and herbicide tillage systems. Winter wheat was sown at the end of September in the amount of 450 seeds/m2. Before pre-sow ploughing, nitrogen, phosphorus, and potassium fertilizers were Material and methods applied in the following doses: 20 kg N/ha, 30 kg P/ ha, and 85 kg K/ha. In the springtime, after vegetation Study site and habitat conditions resumed, wheat crops were fertilized with nitrogen in three terms: (1) 70 kg/ha at the tillering stage (22-23 in A field experiment was established in 2007 at the BBCH scale) (BBCH Working Group, 2001); (2) 40 kg/ Uhrusk Experimental Station (51°18'11"N, 23°36'43"E), ha at the shooting stage (32-33 BBCH); and (3) 20 kg/ whereas data presented herein were collected in 2014- ha at the beginning of ear formation (52-53 BBCH). The 2016. The soil on which the experiment was conducted total amount of fertilizers reached 150 kg N/ha. In each was Rendzic Phaeozem, according to the classification study year, wheat was harvested between the 1st and 5th of IUSS Working Group WRB (2015). The soil is of August using a Wintersteiger plot harvester. characterized by alkaline pH (pHKCL=7.2), high contents Wheat crops were protected against fungal diseases of phosphorus (133 mg P/kg DM) and potassium (310 using fungicides: 1.0 L/ha of Alert 375 SC (a.i. flusilazole mg K/kg DM), but low content of magnesium (37 mg + carbendazim) at the shooting stage (31-32 BBCH) Mg/kg DM). Contents of total nitrogen, nitrate nitrogen and 1.0 L/ha of Tilt Turbo 575 EC (a.c. propiconazol + (N-NO3), ammonia nitrogen (N-NH4), and organic C in fenpropidin at the ear formation stage) (43-44 BBCH). the soil reach: 0.97 g N/kg DM, 30.8 mg/kg DM, 1.21 Weed control included spraying with 1.5 L/ha of Chwastox mg/kg DM, and 6.38 g/kg DM, respectively. Trio (MCPA + mecoprop + dicamba) at the tillering stage At study area, the average annual sum of precipitation (23-24 BBCH), i.e. after the first term of weed infestation since wheat sowing till harvest, i.e. since September till assessment. August, reaches 580 mm, whereas the highest monthly precipitation occurs in May (65 mm), June (73 mm), Yield parameters and statistical analysis and July (80 mm). The average air temperature in the vegetative season of wheat (since March to August) Weed infestation was evaluated with the botanical- is 12.6 °C, whereas the highest average monthly air gravimetric method in two terms: (1) at the tillering temperatures occur in June (16.7 °C), July (18.4 °C), stage (22-23 BBCH) and (2) at the waxy maturity stage and August (17.6 °C). In winter months, the average of wheat (82-83 BBCH). Determinations conducted in monthly air temperatures reach -1.8 °C in December, term (1) included the number and species composition -4.0 °C in January, and -2.8 °C in February, while sums of weeds/m2, whereas these conducted in term (2) Spanish Journal of Agricultural Research December 2018 • Volume 16 • Issue 4 • e1009 3 Effect of tillage system on the structure of weed infestation of winter wheat included the number, air-dry weight produced by weeds Table 1.