The Competitive Ability of Weed Community with Selected Crucifer Oilseed Crops

Dedicated production of energy crops on agricultural land is expected to be a crucial source of biomass to be exploited in order to achieve the renewable energy targets in the European Union. Vegetable oils are the main source for the production of biofuel; therefore, an alternative is to use oils from non-food oilseed crops. Oilseed crops examples include rapeseed, crambe and camelina

Increasing crop rotational diversity can enhance cereal yields

9 Pág.Diversifying agriculture by rotating a greater number of crop species in sequence is a promising practice to reduce negative impacts of crop production on the environment and maintain yields. However, it is unclear to what extent cereal yields change with crop rotation diversity and external nitrogen fertilization level over time, and which functional groups of crops provide the most yield benefit. Here, using grain yield data of small grain cereals and maize from 32 long-term (10–63 years) experiments across Europe and North America, we show that crop rotational diversity, measured as crop species diversity and functional richness, enhanced grain yields. This yield benefit increased over time. Only the yields of winter-sown small grain cereals showed a decline at the highest level of species diversity. Diversification was beneficial to all cereals with a low external nitrogen input, particularly maize, enabling a lower dependence on nitrogen fertilisers and ultimately reducing greenhouse gas emissions and nitrogen pollution. The results suggest that increasing crop functional richness rather than species diversity can be a strategy for supporting grain yields across many environments.G.V., R.B. and S.H. acknowledge FORMAS grants 2018-02872 and 2018-02321. TMB acknowledges USDA AFRI grant 2017-67013-26254. LTEs managed by SRUC were supported by the Scottish Government RESAS Strategic Research Programme under project D3-, Healthy Soils for a Green Recovery. Swedish LTEs were funded by the Swedish University of Agricultural Sciences (SLU). We thank the Lawes Agricultural Trust and Rothamsted Research for data from the e-RA database. The Rothamsted Long-term Experiments National Capability (LTE-NC) was supported by the UK BBSRC (Biotechnology and Biological Sciences Research Council, BBS/E/C/000J0300) and the Lawes Agricultural Trust. The Woodslee site was supported by the Agro-Ecosystem Resilience Program (Agriculture & Agri-Food Canada) and field management provided by field crews over 6 decades is appreciated. La Canaleja LTE (Spain) was supported by RTA2017-00006-C03-01 project (Ministry of Science and Innovation. El Encín LTEs were supported by Spanish Ministry of Economy and Competitiveness funds (projects AGL2002-04186-C03-01.03, AGL2007-65698-C03-01.03, AGL2012-39929-C03-01 of which L. Navarrete was the P.I). R.A., A.G.D. and E.H.P. are also grateful to all members of the Weed Science Group from El Encín Experimental Station for their technical assistance in managing the experiments. The Brody/Poznan University of Life Sciences long-term experiments were funded by the Polish Ministry of Education and Science. We acknowledge the E-Obs dataset from the EU-FP6 project UERRA (http://www.uerra.eu) and the Copernicus Climate Change Service, and the data providers in the ECA&D project (https://www.ecad.eu/).Peer reviewe

Increasing crop rotational diversity can enhance cereal yields

Diversifying agriculture by rotating a greater number of crop species in sequence is a promising practice to reduce negative impacts of crop production on the environment and maintain yields. However, it is unclear to what extent cereal yields change with crop rotation diversity and external nitrogen fertilization level over time, and which functional groups of crops provide the most yield benefit. Here, using grain yield data of small grain cereals and maize from 32 long-term (10–63 years) experiments across Europe and North America, we show that crop rotational diversity, measured as crop species diversity and functional richness, enhanced grain yields. This yield benefit increased over time. Only the yields of winter-sown small grain cereals showed a decline at the highest level of species diversity. Diversification was beneficial to all cereals with a low external nitrogen input, particularly maize, enabling a lower dependence on nitrogen fertilisers and ultimately reducing greenhouse gas emissions and nitrogen pollution. The results suggest that increasing crop functional richness rather than species diversity can be a strategy for supporting grain yields across many environments

Crop rotational diversity can mitigate climate-induced grain yield losses

Diversified crop rotations have been suggested to reduce grain yield losses from the adverse climatic conditions increasingly common under climate change. Nevertheless, the potential for climate change adaptation of different crop rotational diversity (CRD) remains undetermined. We quantified how climatic conditions affect small grain and maize yields under different CRDs in 32 long-term (10-63 years) field experiments across Europe and North America. Species-diverse and functionally rich rotations more than compensated yield losses from anomalous warm conditions, long and warm dry spells, as well as from anomalous wet (for small grains) or dry (for maize) conditions. Adding a single functional group or crop species to monocultures counteracted yield losses from substantial changes in climatic conditions. The benefits of a further increase in CRD are comparable with those of improved climatic conditions. For instance, the maize yield benefits of adding three crop species to monocultures under detrimental climatic conditions exceeded the average yield of monocultures by up to 553 kg/ha under non-detrimental climatic conditions. Increased crop functional richness improved yields under high temperature, irrespective of precipitation. Conversely, yield benefits peaked at between two and four crop species in the rotation, depending on climatic conditions and crop, and declined at higher species diversity. Thus, crop species diversity could be adjusted to maximize yield benefits. Diversifying rotations with functionally distinct crops is an adaptation of cropping systems to global warming and changes in precipitation.</p

Competition for nitrogen between thorn apple and tomato and pepper

The effect of emergence time of the weed Datura stramonium (thorn apple) on tomato (Lycopersicon esculentum Mill.) and pepper (Capsicum annuum L.) was evaluated in a greenhouse experiment. The closer emergence of the weed was to that of the crops, the greater was the weed's growth, seed production, and nitrogen (N) uptake. As a result, growth, fruit yield, and N uptake of the crops was reduced. Shoot N content was reduced in tomato, as was fruit N content in pepper. There was competition by the weed with the crops for N, even when weed emergence was as late as the beginning of flowering. This competition, and the damage it caused, was always more severe with respect to pepper than tomato, irrespective of weed emergence time. The earlier the emergence of Datura stramonium, the fewer were the number of fruits produced by either crop. Average fresh fruit weight in tomato was also reduced. In pepper, the average fruit weight was reduced only when the weed emerged up to the four-leaf stage of the crop. The drop in pepper fruit yield caused by weed emergence up to the four-leaf stage of the crop could be due to competition for light by the weed, in addition to competition for N. Tomato competed better against the weed than did pepper. Copyright © Taylor & Francis Group, LLC

Effect of nitrogen fertilization schedule and herbicide on competition between barley and ryegrass

This paper reports the effect of different nitrogen (N) fertilization schedules, weather conditions, and herbicide use on the competition between barley (Hordeum vulgare L.) and a weed, ryegrass (Lolium rigidum). The ability of the weed to compete was increased by high rainfall during autumn and winter followed by low rainfall during the spring. Good distribution of rainfall during the growing season, however, favored the crop plant over the weed. In general, competition from Lolium rigidum reduced barley biomass, straw yield, grain yield, harvest index, total nitrogen accumulation, and nitrogen translocation efficiency to the grain. The nitrogen fertilization applied in the growth season was 120 kg ha- 1. Applying the entire complement of fertilizer during early barley tillering (N0 + 120) benefited ryegrass, increasing its ability to compete with the crop; regardless of herbicide use. When the full fertilizer complement was applied during the pre-sowing period (N120 + 0), or when half was applied during pre-sowing and half during early crop tillering (N60 + 60), the Lolium rigidum biomass recorded was the same (although less than obtained with the N0 + 120 schedule). The N60 + 60 schedule led to greater barley biomass and nitrogen accumulation than the N120 + 0 schedule. When rainfall was well distributed over the growth season, the barley grain yield did not vary with respect to fertilization schedule. However, when rainfall was intense during the autumn/winter, the greatest grain yield was achieved with the N60 + 60 schedule, followed by the N120 + 0 and N0 + 120 schedules. Copyright © Taylor & Francis Group, LLC

Effects of size and moisture of rhizome on initial invasiveness ability of giant reed

Studies were conducted under controlled conditions to determine growth and reproductive capabilities of Arundo donax L. (giant reed), a riparian invasive perennial plant that has spread widely. Greenhouse experiments were conducted to determine the influence of rhizome size and moisture content in the early invasiveness ability of giant reed. We tested different sizes of rhizomes rhizome size of 1 cm, 3 cm, 5 cm and shredded rhizome. (fragments < 1 cm). These rhizomes were observed at 7, 14, 21, 28 and 35 days after planting (DAP). To test the effect of moisture content we used fresh rhizome fragments; rhizomes with moderate dehydration (50%); rhizomes with high dehydration (over 70%) with 48 hours of rehydration and rhizomes with high dehydration (70-90%). The rhizomes monitored for moisture content and biomass increase were between 3 and 5 cm, and were observed 60 DAP. The initial size of rhizomes affected the level of sprouting. Rhizomes with low moisture content (due to dehydration) showed high increase in biomass compared with the rhizomes that had not been treated or had been dehydrated and then rehydrated. Our results indicated that size of rhizomes is related to regrowth and low moisture (dehydration) content can be overcome by this species. This could be linked to high rates of colonization and early establishment ability of this species even after mechanical treatment of rhizomes, in riparian environments. © 2014 Copyright Taylor and Francis Group, LLC

Weed abundance and soil seedbank responses to tillage systems in continuous maize crops

Weed abundance in crops undergoes frequent changes, often due to changes in tillage practices. Annual species, with quick germination, a short vegetative stage, profuse seed production and long-lived seeds become problematic under zero-tillage systems. Portulaca oleracea L. and Amaranthus blitoides L. are widespread weeds in the Mediterranean area, prominent in irrigated crops. We studied the total weed abundance in the field, and specifically these two species (Portulaca oleracea and Amaranthus blitoides) with high frequency of occurrence in monoculture maize, from 2012 to 2014, in the field and soil seedbank. Results showed significant differences between zero-tillage (ZT) and conventional tillage (CT) systems on total weed abundance and relative abundance of Portulaca oleracea. Total weed abundance decreased in ZT plots (from 136 plants m−2 to 25 and 46 plants m−2, in 2013 and 2014 respectively). The same trend was observed in Portulaca oleracea recorded in ZT plots, but the abundance of Amaranthus blitoides did not vary in this system. Weed seedling germination and weed seed numbers both of total weed seedbank and Portulaca oleracea, were greater in ZT plots compared to CT, regarding Amaranthus blitoides seedling germination and seed count, the values did not increase with ZT, in continuous maize crop

Effects of sprout cutting plus systemic herbicide application on the initial growth of giant reed

Chlorophyll fluorescence analysis (CFA) has been successfully used to rapidly determine the responses of different plants to herbicides. It has not, however, been used to test the effect of these products on invasive riparian species. This paper reports the use of CFA to determine photosynthetic activity in Arundo donax, an invasive reed causing serious problems in Mediterranean riparian habitats, in response to systemic herbicide application following cutting. Growth was measured in terms of new sprout relative height and sprout and rhizome relative biomass. CFA showed glyphosate, from half the on-label dose of 5 L ai.ha-1upwards, to have a significant effect (100% reduction) on photosynthetic activity at 21 days after treatment (DAT), while profoxydim, from half the on-label dose of 0.375 L ai.ha-1upwards, caused a 70% reduction soon after application, although these plants later recovered. Azimsulfuron, cyhalofop-butyl and penoxsulam had no significant effect on photosynthetic activity at any dose. At 60 DAT, glyphosate (from half the on-label dose of 5 L ai.ha-1upwards) was associated with a 90% reduction in sprout height, while profoxydim (from half the on-label dose of 0.375 L ai.ha-1upwards) caused a 50% reduction. No dose (0-2x the on-label dose) of azimsulfuron, penoxsulam or cyhalofop-butyl was associated with any significant growth reduction at 60 DAT. The results show that CFA can be used to successfully measure the response of these invasive plants to herbicides, and that glyphosate, and possibly profoxydim, might be used to control Arundo donax after initial cutting. © 2013 Copyright Taylor and Francis Group, LLC