The influence of crop density and sowing delay on weed germination in winter wheat

Aufgrund von Veränderungen in ackerbaulichen Anbauverfahren wie z.B. der Anwendung reduzierter Bodenbearbeitungsmaßnahmen und de m Anbau von Monokulturen, klimatischen Veränderungen, die zu längeren, wärmeren Perioden im Herbst führen können sowie aufgrund der Ausbreitung von Herbizidresistenz nimmt die Bedeutung von integrierten Lösungen zur Unkrautbekämpfung zu. Die Erhöhung der Konkurrenzkraft der Kulturpflanze ist eine von vielen ackerbaulichen Maßnahmen, die im Rahmen einer integrierten Unkrautbekämpfung angewendet werden können. Spätere Aussaattermine oder erhöhte Aussaatdichten können ebenso als effektive Maßnahmen angesehen werden, da dichtere Kultur-Pflanzenbestände generell eine höhere Konkurrenzkraft gegenüber den Unkräutern aufweisen können.Zwei Feldversuche wurden in 2014-2016 am Institute of Agriculture, LRCAF, durchgeführt um den Einfluss von Bestandesdichte und späterem Aussaatzeitpunkt von Winterweizen in konventionellen Bodenbearbeitungssystemen zu untersuchen. Die Winterweizensorte ‘Ada’ wurden mit drei verschiedenen Bestandesdichten (2, 4 und 8 Millionen keimfähige Samen pro ha) und zu drei verschiedenen Aussaatzeitpunkten (regional empfohlener Aussaatzeitpunkt, drei Wochen später und sechs Wochen später) gedrillt. Die Hauptunkrautarten in den Versuchen waren einjährige zweikeimblättrige Arten, die typisch für Wintergetreide sind, wie Thlaspi arvense, Viola arvensis, Galium aparine und Lamium purpureum. Zudem traten Ausfallraps und einjährige einkeimblättrige Arten wie Apera spica-venti auf. In den Parzellen mit den höchsten Bestandesdichten war das Unkrautaufkommen am niedrigsten. Allerdrings traten vor allem in Parzellen mit dem früheren Aussaatzeitpunkt Verschlämmungsprobleme auf. Bei späteren Aussaatterminen traten deutlich weniger Unkräuter auf als bei den früheren Aussaatzeitpunkten. Das geringste Unkrautaufkommen wurde in Parzellen mit dem spätesten Aussaatzeitpunkt beobachtet, allerdings war in diesen Parzellen auch der Ertrag des Winterweizens reduziert.Due to changes in agronomic practices and cropping systems such as the development of reduced soil tillage systems, monocropping; changing climate conditions that result in longer warmer periods in autumn and due to other factors such as herbicide resistance approaches for integrated weed management are needed. Crop competitiveness could be one of several measures of cultural weed control, which is an important factor in integrated weed control. Delayed sowing dates or higher crop seed rates could be an integrated tool for weed management, because higher crop plant densities generally are more competitive with weeds. Two field trials were conducted to investigate the influence of winter wheat plant density and delay of sowing date at the Institute of Agriculture, LRCAF in conventional soil tillage system over the period of 2014 –-2016. Winter wheat var. ‘Ada’ was drilled at three different seeding rates (2, 4 and 8 million germinal seeds per hectare) at the regional recommended sowing date, three weeks later and six weeks later. Main weeds in winter wheat crops were annual dicotyledonous, common for the winter cereals stands in Lithuania such as Thlaspi arvense, Viola arvensis, Galium aparine and Lamium purpureum. Furthermore, volunteer oilseed rape and the annual monocotyledonous weed Apera spica-venti were presented in the field. Admittedly, meteorological conditions were favourable for cereals vegetation during the autumn.In plots with the highest seeding rate weed biomass was significantly lower, however lodging problem, especially in early seeded plots occurred. The weed biomass in plots drilled at the end of September was significantly lower compared to early drilled plots. The lowest weed mass was recorded in plots with the latest sowing date, however a significant decrease in grain yield was recorded in these plots

Developmental morphology of cover crop species exhibit contrasting behaviour to changes in soil bulk density, revealed by X-ray computed tomography

Plant roots growing through soil typically encounter considerable structural heterogeneity, and local variations in soil dry bulk density. The way the in situ architecture of root systems of different species respond to such heterogeneity is poorly understood due to challenges in visualising roots growing in soil. The objective of this study was to visualise and quantify the impact of abrupt changes in soil bulk density on the roots of three cover crop species with contrasting inherent root morphologies, viz. tillage radish (Raphanus sativus), vetch (Vicia sativa) and black oat (Avena strigosa). The species were grown in soil columns containing a two-layer compaction treatment featuring a 1.2 g cm-3 (uncompacted) zone overlaying a 1.4 g cm-3 (compacted) zone. Three-dimensional visualisations of the root architecture were generated via X-ray computed tomography, and an automated root-segmentation imaging algorithm. Three classes of behaviour were manifest as a result of roots encountering the compacted interface, directly related to the species. For radish, there was switch from a single tap-root to multiple perpendicular roots which penetrated the compacted zone, whilst for vetch primary roots were diverted more horizontally with limited lateral growth at less acute angles. Black oat roots penetrated the compacted zone with no apparent deviation. Smaller root volume, surface area and lateral growth were consistently observed in the compacted zone in comparison to the uncompacted zone across all species. The rapid transition in soil bulk density had a large effect on root morphology that differed greatly between species, with major implications for how these cover crops will modify and interact with soil structure

The effect of different tillage-fertilization practices on the mycoflora of wheat grains

A two-factor field experiment was carried out at the Lithuanian Institute of Agriculture during the period 2005-2008. The influence of different tillage and fertilization practices on wheat grain fungal contamination was evaluated. Grain surface contamination and internal grain infection with fungi were quantified using agar tests. Purified colonies were identified using different manuals. A total of 16 fungal genera were identified in spring and winter wheat grains. Alternaria infected 46.3% - 99.9%, Cladosporium 26.9% - 77.8%, Fusarium 0.9% - 37.1%, Penicillium 1.3% - 2.5% of grains tested. Winter wheat grain surface contamination by fungi ranged from 7.2 × 103 to 24.8 × 103 of colony forming units per g of grain (cfu g-1), spring wheat from 14.8 × 103 to 80.3 × 103 cfu g-1. No-tillage increased winter wheat grain infection by Alternaria, Aspergillus and Cladosporium species and total count of cfu g-1 on spring wheat grain surface. High fertilizer rates resulted in an increase in spring wheat grain infection by Fusarium and Penicillium species and total count of cfu g-1 on both spring and winter wheat grain surface.

Influence of Different Intensities of Tillage on Physiological Characteristics and Productivity of Crop-Rotation Plants

The aim of this study was to evaluate the effect of different intensities of tillage on the physiological characteristics and productivity of plants in crop rotation. Five tillage practices (DP—deep ploughing (22–24 cm); SP—shallow ploughing (16–18 cm); SH—shallow harrowing (8–10 cm); DH—deep harrowing (14–16 cm); and DD—direct drilling) were investigated in a long-term experiment in Dotnuva. The crop rotation was as follows: winter oilseed rape → spring wheat → spring barley → field pea → winter wheat. The simplification of conventional tillage negatively affected the photosynthetic indices of the majority of the crop rotation plants. The most favorable conditions for the photosynthetic processes in the plants were identified in the deep-ploughing treatment. The photochemical activity was negatively influenced and leaf senescence was accelerated under direct drilling. Direct drilling significantly decreased the grain yield of winter oilseed rape, spring wheat, and spring barley by 10.5%, 12.8%, and 17.2%, respectively, compared to deep ploughing. The grain yield of winter wheat was similar under deep ploughing and direct drilling; conversely, under shallow ploughing, shallow harrowing, and deep harrowing, the yield tended to decrease compared to deep ploughing

Toxigenicity of <i>F. graminearum</i> Residing on Host Plants Alternative to Wheat as Influenced by Environmental Conditions

Fusarium graminearum is an important pathogen that causes Fusarium head blight (FHB) in several cereal crops worldwide. The potential of this pathogen to contaminate cereals with trichothecene mycotoxins presents a health risk for both humans and animals. This study aimed to evaluate the potential of different trichothecene genotypes of F. graminearum isolated from an alternative host plant to produce mycotoxins under different spring wheat grain incubation conditions. Fourteen F. graminearum strains were isolated from seven alternative host plants and identified as 3-acetyl-deoxynivalenol (3-ADON) and 15-acetyl-deoxynivalenol (15-ADON) genotypes. These strains were cultivated on spring wheat grains at 25 °C and 29 °C for 5 weeks. The mycotoxins produced were analysed with a high-performance liquid chromatograph (HPLC) coupled to a Thermo Scientific TSQ Quantiva MS/MS detector. The obtained results showed that the F. graminearum strains from alternative host plants could produce nivalenol (NIV), deoxynivalenol (DON), fusarenon-X (FUS-X), 3-ADON, deoxynivalenol-3-ß-d-glucoside (D3G), 15-ADON, and zearalenone (ZEA). F. graminearum strains produced DON and ZEA under both temperatures, with the mean concentrations varying from 363 to 112,379 µg kg−1 and from 1452 to 44,816 µg kg−1, respectively. Our results indicated the possible role of dicotyledonous plants, including weeds, as a reservoir of inoculum sources of F. graminearum-induced Fusarium head blight, associated with the risk of mycotoxin contamination in spring wheat

The effect of different tillage-fertilization practices on the mycoflora of wheat grains

A two-factor field experiment was carried out at the Lithuanian Institute of Agriculture during the period 2005-2008. The influence of different tillage and fertilization practices on wheat grain fungal contamination was evaluated. Grain surface contamination and internal grain infection with fungi were quantified using agar tests. Purified colonies were identified using different manuals. A total of 16 fungal genera were identified in spring and winter wheat grains. Alternaria infected 46.3% - 99.9%, Cladosporium 26.9% - 77.8%, Fusarium 0.9% - 37.1%, Penicillium 1.3% - 2.5% of grains tested. Winter wheat grain surface contamination by fungi ranged from 7.2 × 103 to 24.8 × 103 of colony forming units per g of grain (cfu g-1), spring wheat from 14.8 × 103 to 80.3 × 103 cfu g-1. No-tillage increased winter wheat grain infection by Alternaria, Aspergillus and Cladosporium species and total count of cfu g-1 on spring wheat grain surface. High fertilizer rates resulted in an increase in spring wheat grain infection by Fusarium and Penicillium species and total count of cfu g-1 on both spring and winter wheat grain surface.vo

Susceptibility of non-cereal crops to Fusarium graminearum complex and their role within cereal crop rotation as a source of inoculum for Fusarium head blight

Fusarium graminearum, the cause of Fusarium head blight (FHB), is an important cereal pathogen. Moreover, some non-graminaceous crops are also known to be susceptible to F. graminearum infection. This study assessed the presence of F. graminearum species complex on non-cereal plants, grown in a cereal crop rotation and evaluated its pathogenicity to non-cereal plants in vitro and to spring wheat under field conditions. The relative density of Fusarium species isolated from oilseed rape, pea, potato and sugar beet plants was assessed in 2015 and 2016. A total of 403 isolates of Fusarium spp. were obtained from non-cereal plants and only 5% of the isolates were identified as F. graminearum. The pathogenicity test revealed that isolates of F. graminearum from spring wheat and non-cereal plants caused discolourations on leaves of faba bean, fodder beet, oilseed rape, pea, potato and sugar beet. The pea was the crop most susceptible to F. graminearum isolated from spring wheat. The pathogenicity of F. graminearum from sugar beet, oilseed rape, pea and potato to the same hosts differed depending on isolate and inoculated plant. Under field conditions, F. graminearum isolates from pea, potato, oilseed rape and wild viola were able to cause typical FHB symptoms in spring wheat. Based on the information generated in this study, we conclude that under congenial conditions, growing faba bean, pea, sugar beet, fodder beet, oilseed rape and potato plants in a cereal crop rotation may serve as alternative or reservoir hosts for F. graminearum pathogens

Susceptibility of non-cereal crops to Fusarium graminearum complex and their role within cereal crop rotation as a source of inoculum for Fusarium head blight

Fusarium graminearum, the cause of Fusarium head blight (FHB), is an important cereal pathogen. Moreover, some non-graminaceous crops are also known to be susceptible to F. graminearum infection. This study assessed the presence of F. graminearum species complex on non-cereal plants, grown in a cereal crop rotation and evaluated its pathogenicity to non-cereal plants in vitro and to spring wheat under field conditions. The relative density of Fusarium species isolated from oilseed rape, pea, potato and sugar beet plants was assessed in 2015 and 2016. A total of 403 isolates of Fusarium spp. were obtained from non-cereal plants and only 5% of the isolates were identified as F. graminearum. The pathogenicity test revealed that isolates of F. graminearum from spring wheat and non-cereal plants caused discolourations on leaves of faba bean, fodder beet, oilseed rape, pea, potato and sugar beet. The pea was the crop most susceptible to F. graminearum isolated from spring wheat. The pathogenicity of F. graminearum from sugar beet, oilseed rape, pea and potato to the same hosts differed depending on isolate and inoculated plant. Under field conditions, F. graminearum isolates from pea, potato, oilseed rape and wild viola were able to cause typical FHB symptoms in spring wheat. Based on the information generated in this study, we conclude that under congenial conditions, growing faba bean, pea, sugar beet, fodder beet, oilseed rape and potato plants in a cereal crop rotation may serve as alternative or reservoir hosts for F. graminearum pathogens