Effect of crop rotation on weed seed bank

Knowledge of weed soil seed bank is of great importance for forecasting weediness for next years. Crop rotation and tillage are two primary practices that have an impact on soil seed bank. In our study, soil samples were taken in order to evaluate the size and species composition of the weed seed bank in the soil on plots under different growing systems: monoculture of corn of about 40 years, crop rotation of corn, wheat and soybeans with different variations of fertilization. Samples were collected during October, using probe (diameter 5 cm) in a layer of 15 cm. Four soil samples collected from 10 sampling points were taken from each of 7 plots. Seeds were extracted from the soil by washing and were determined and counted. Next year (during August) weediness (abundance and species composition) evaluated in the same plots. The weed seed bank was dominated by Chenopodium album, Amaranthus retroflexus, Datura stramonium, Sorghum halepense in all treatments. In the plots which were under wheat in the previous year, beside the listed species, seeds of species characteristic for grain crops were also present as dominant. The higher number of seeds was observed in treatments where manure was applied. In the unfertilized treatments the seed bank was higher and represented by a higher number of weed species than in other plots. Composition of weed species emerged in the next year were in accordance with results of seed bank analysis and the fact that the investigated plots were seeded to maize. In fact, the dominant species were those typical of row crops

The effect of ryegrass (Lolium italicum L.) stand densities on its competitive interaction with cleavers (Galium aparine L.) [İtalyan çiminin (Lolium italicum L.) farkl? yogunluklar?n?n yogurtotu (Galium aparine L.) ile rekabetine etkileri]

Italian ryegrass (Lolium italicum L. cv. Tetraflorum) seed production is an important industrial activity in Serbia. Cleavers (Galium aparine L.) interferes in Italian ryegrass seed production as well as in many other crops. The effect of stand density of Italian ryegrass on its competitive interaction with cleavers was investigated in western Serbia in the 2005-2006 and 2006-2007 cropping seasons. The established density treatments of Italian ryegrass were 5 kg ha-1 seeding rate with 60 cm row spacing (SD1), 5 kg ha-1 with 20 cm (SD2), 20 kg ha-1 with 60 cm (SD3), and 20 kg ha-1 with 20 cm (SD4). The interaction between Italian ryegrass and cleavers was evaluated by SPAD reading, relative nitrogen content (RNC) in the leaf, total nitrogen content (TNC) in the leaf, and seed yield. The rank order of the competitive ability of Italian ryegrass was SD4 > SD3 > SD2 > SD1 under optimal weather conditions for crop development. Under climatic stress conditions, however, neither effect of ryegrass densities nor cleavers was pronounced on competitive ability of ryegrass with different stands. © TÜBITAK

The response of Chenopodium album L. and Abutilon theophrasti Medik. to reduced doses of mesotrione

The application of minimal doses of herbicides is very popular due to concerns about the negative impacts of herbicides on the environment and public health. Studies were conducted to estimate the possibility of using quick and non- destructive methods to investigate Chenopodium album L. and Abutilon theophrasti Medik. response to mesotrione. The studies were conducted in a controlled environment to determine the response of C. album and A. theophrasti to mesotrione using dose-response curves created based on plant dry weight, chlorophyll fluorescence parameters and chlorophyll content. The obtained effective dose values showed that the studied weeds were susceptible to reduced doses of mesotrione. ED95 values estimated for both species for dry weight and chlorophyll fluorescence parameters were lower than the recommended dose rate (120 g a.i. ha(-1)), with less than 85 g a.i. ha(-1) needed to achieve a reduction of 95%, compared with untreated plants, while ED95 value (A. theophrasti: 182 g a.i. ha(-1) and C. album: 180 g a.i. ha(-1)) for chlorophyll content for both species was above the recommended dose rates. Consequently, dry weight and the chlorophyll fluorescence parameters are suitable for estimating the plant response to mesotrione, while chlorophyll content is not

Biodiversity, utilization and management of grasslands of salt affected soils in Serbia

Salt affected soils especially in the arid and semi-arid regions of the world exhibit a significant increasing tendency. The relationship between plant/vegetation richness and soil salinity was assessed for 21 grassland asscociations and one subassociation of Serbia. Among studied grasslands, the ass. Halo-Crypsidetum aculeatae, Suaedetum maritimae and Salicornieto-Suaedetum maritimae were found to be indicators of the extremely saline soils (solonchak), whereas the ass. Lepidio crassifolio-Festucetum pseudovinae , Trifollietum subterranei and Peucedano-Asteretum punctati were typical indicators of sodic soils (solonetz). Management and use of grasslands of salt affected soils and evaluation of pastoral value and salinity tolerance of the studied grasslands was performed

Effects of spring nitrogen application on Italian ryegrass seed production and its competition with cleavers

24th General Meeting of the European-Grassland-Federation -- JUN 03-07, 2012 -- Lublin, POLANDWOS: 000361159300147A field study in western Serbia evaluated during two seasons (from 2005 to 2007) the effect of nitrogen (N) fertilizer application on Italian ryegrass (Lolium italicum Lam.) grown for seed and its competitive interaction with cleavers (Galium aparine L.) in the year after establishment. Increasing rates of N fertilizer (control, N-1-50, N-2-100 and N-3-150 kg ha(-1) N) and two ryegrass sowing rates (5 and 20 kg ha(-1)) were used. The increase of fertilizer N level improved competitive ability of ryegrass and affected the interspecific competitive interactions. The interaction between Italian ryegrass and cleavers was evaluated by measuring total nitrogen content (TNC) in the leaf during vegetation and seed yield at the end of vegetation period. The highest seed yield was obtained with 100 kg ha(-1) N in both experimental years as well as in ryegrass monoculture and ryegrass-cleavers mixture. Competition with cleavers decreased ryegrass seed yield.Kuhn, Ministerstwo Rolnictwa Rozwoju Wsi, Lubelski Wegiel Bogdanka S A, Karol Kania Synowie, Rolimpex, Dept Rolnictwa Srodowiska Urzedu Marszalkowskiego Wojewodztwa, Lubelskiego, Linia Hutnicza Szerokotorowa, Powiat Bilgorajski, Centinas, DSV Polska, Perla Browary Lubelskie, Lubella, Uniwersytet Przyrodniczy w Lublinie, Miasto Lublin, Apis, Herbapol Lublin S A, OSM Krasnystaw, Powiat Krasnostawski, Powiat Lubelski, Powiat Krasnystaw, Lubelska Izba Rolnicza, Gmina Krasnystaw, Urzad Miasta Krasnysta

A contribution to studies of the ruderal vegetation of southern Srem, Serbia

Floristic research investigating the presence and phytocoenological differentiation of ruderal vegetation, and how it is conditioned structurally and anthropogenically, was undertaken over a period of several years (2007-10) in the south Srem region. The ruderal flora of the research area comprised 249 plants categorized into 63 families, of which the most frequent were: Asteraceae (36), Poaceae (29), Fabaceae (18), Lamiaceae (15), Polygonaceae (15), Brassicaceae (11) and Rosaceae (11). Three ruderal communities are analyzed in this work: Asclepietum syriacae Kojić et al., 2004, as well as Chenopodio-Ambrosietum artemisiifoliae ass. nova and Amorpho-Typhaetum ass. nova, which are described for the first time. It was established that the level of moisture at the habitat, anthropogenic factors, and the immediate proximity to cultivated areas had the most pronounced effect on the differentiation of the researched vegetation

Delay in the critical time for weed removal in imidazolinone-resistant sunflower (Helianthus annuus) caused by application of pre-emergence herbicide

The critical time for weed removal (CTWR) is a period in the crop growth cycle when weed control must be initiated to prevent yield losses. Knowing the CTWR is useful for making decisions about the timing of weed control and in achieving efficient herbicide use from both biological and economic perspectives. Field studies were conducted in 2008 and 2009 at three locations in Serbia and one location in the USA to determine the CTWR in imidazolinone (IMI)-resistant sunflower grown with and without application of pre-emergence (PRE) herbicide. A four-parameter log-logistic model was fitted to data relating relative crop yield to increasing duration of weed presence. The CTWR without PRE herbicide treatment ranged from 14 to 26d after emergence (DAE) corresponding to the V3 (three leaves) to V4 stages compared to 25 to 37 DAE, which corresponded to the V6 to V8 stages with PRE herbicide. The CTWR in IMI-resistant sunflower grown with PRE herbicide can be delayed by an additional 6 to 12 d compared to the crop grown without PRE herbicide under the present experimental conditions. The practical implication of this study is that the use of PRE herbicide could extend post-herbicide treatments by another 6 to 12d with respect to the critical time required for weed removal without PRE herbicide in IMI-resistant sunflower