Mixed Growth with Weeds Promotes Mycorrhizal Colonization and Increases the Plant-Availability of Phosphorus under Maize (Zea mays L.)

(1) Background: Weed control decreases the competition for nutrients, but also the potential of increased phosphorus (P) mobilization in soils caused by higher plant diversity. (2) Methods: Impacts of weed species under maize on mycorrhizal colonization and plant-availability of P were investigated in two pot experiments. Plant traits and P mobilization were tested in weed-free maize and in mixed growth with six annual weed species. (3) Results: Growth of maize decreased in treatments with weeds, while P concentrations in its shoots increased in mixed growth with C. album, E. crus-galli and P. convolvulus. Mycorrhizal colonization of maize without weeds was low (<20% of root length), but increased in mixed growth with C. album, E. crus-galli and V. arvensis up to 40%. The activities of Pmobilizing hydrolytic enzymes (phosphatases, ß-glucosidase) and plant-availability of P were occasionally higher under mixed growth with weeds. The dimension of weed impacts on P cycling under maize differed significantly between both experiments. (4) Conclusions: Weeds potentially promote P mobilization and mycorrhizal colonization under maize, but this impact is not guaranteed. The weed-based improved P supply of maize should be defined under field conditions to allow a controlled weed tolerance in maize cropping systems.

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Influence of chaff and chaff lines on weed seed survival and seedling emergence in Australian cropping systems

Weed Technology ◽

10.1017/wet.2020.142 ◽

2020 ◽

pp. 1-22

Author(s):

Michael J. Walsh ◽

Annie E. Rayner ◽

Annie Rutledge ◽

John C. Broster

Keyword(s):

Cropping Systems ◽

Seedling Emergence ◽

Field Studies ◽

Wild Oat ◽

Weed Seed ◽

Weed Species ◽

Environment Effect ◽

Seed Survival ◽

Cropping Seasons ◽

Rigid Ryegrass

Abstract Chaff lining and chaff tramlining are harvest weed seed control (HWSC) systems that involve the concentration of weed seed containing chaff material into narrow (20 to 30 cm) rows between or on the harvester wheel tracks during harvest. These lines of chaff are left intact in the fields through subsequent cropping seasons in the assumption that the chaff environment is unfavourable for weed seed survival. The chaff row environment effect on weed seed survival was examined in field studies, while chaff response studies determined the influence of increasing amounts of chaff on weed seedling emergence. The objectives of these studies were to determine 1) the influence of chaff lines on the summer-autumn seed survival of selected weed species; and 2) the influence of chaff type and amount on rigid ryegrass seedling emergence. There was frequently no difference (P>0.05) in survival of seed of four weed species (rigid ryegrass, wild oat, annual sowthistle and turnip weed) when these seed were placed beneath or beside chaff lines. There was one instance where wild oat seed survival was increased (P<0.05) when seed were placed beneath compared to beside a chaff line. The pot studies determined that increasing amounts of chaff consistently resulted in decreasing numbers of rigid ryegrass seedlings emerging through chaff material. The suppression of emergence broadly followed a linear relationship where there was approximately a 2.0% reduction in emergence with every 1.0 t ha-1 increase in chaff material. This relationship was consistent across wheat, barley, canola and lupin chaff types, indicating that the physical presence of the chaff was more important than chaff type. These studies indicated that chaff lines may not affect the over summer-autumn survival of the contained weed seeds but the subsequent emergence of weed seedlings will be restricted by high amounts of chaff (>40 t ha-1).

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Effects of conservation agriculture on productivity and Economics of maize-wheat based cropping systems in midwestern Nepal

SAARC Journal of Agriculture ◽

10.3329/sja.v17i1.42761 ◽

2019 ◽

Vol 17 (1) ◽

pp. 49-63

Author(s):

K Pariyar ◽

A Chaudhary ◽

P Sapkota ◽

S Sharma ◽

CB Rana ◽

...

Keyword(s):

Grain Yield ◽

Cropping Systems ◽

Cropping System ◽

Conservation Agriculture ◽

Crop Productivity ◽

Conventional Tillage ◽

Net Income ◽

Zero Tillage ◽

Higher Plant ◽

Equivalent Yield

The effects of two tillage methods (zero tillage and conventional tillage), two residue managements (residue kept and residue removed) and two levels of cropping system (maize + soybean and sole maize) were studied over 3 years (2015-2017) at Dailekh district of Nepal. Arun-2 and Puja were the varieties of maize and soybean used respectively, followed by winter wheat. The results revealed that the maize + soybean system had significantly higher plant population and ear population (34.83 thousands ha-1 and 34.35 thousands ha-1, respectively), grains per row (37.1), ear length (16.6 cm) and 20.5% higher grain yield as compared to sole maize. The highest maize equivalent yield (7.92 t ha-1) was recorded in maize + soybean as compared to the lower grain yield equivalent (7.06 t ha-1) in sole maize. Zero tillage accounted relatively higher benefits (high net income and B:C ratio) as compared to conventional tillage. The residue kept plot resulted significantly higher B:C ratio (2.41) than the residue removed (2.11) and the maize + soybean recorded 82.5% greater B:C ratio compared to sole maize. Net annual income was significantly higher in zero tillage, residue kept and maize + soybean system (NRs. 223072.00, 222958.00 and 269016.00 ha-1 respectively). Such combinations are recommended for Dailekh district of Nepal to have profitable crop productivity. SAARC J. Agri., 17(1): 49-63 (2019)

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Plant-available P supply is not the main factor determining the benefit from arbuscular mycorrhiza to crop P nutrition and growth in contrasting cropping systems

Plant and Soil ◽

10.1007/s11104-011-0884-x ◽

2011 ◽

Vol 350 (1-2) ◽

pp. 85-98 ◽

Cited By ~ 12

Author(s):

Helena Kahiluoto ◽

Elise Ketoja ◽

Mauritz Vestberg

Keyword(s):

Arbuscular Mycorrhiza ◽

Cropping Systems ◽

Available P ◽

P Nutrition ◽

Plant Available P ◽

P Supply ◽

Main Factor

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Seed germination ecology of Conyza stricta Willd. and implications for management

PLoS ONE ◽

10.1371/journal.pone.0244059 ◽

2020 ◽

Vol 15 (12) ◽

pp. e0244059

Author(s):

Safdar Ali ◽

Fakhar Din Khan ◽

Rehmat Ullah ◽

Rahmat Ullah Shah ◽

Saud Alamri ◽

...

Keyword(s):

Seed Germination ◽

Osmotic Potential ◽

Cropping Systems ◽

Seedling Emergence ◽

Management Strategies ◽

Conservation Agriculture ◽

Weed Species ◽

Seed Burial ◽

Germination Ecology ◽

Tillage Practices

Numerous cropping systems of the world are experiencing the emergence of new weed species in response to conservation agriculture. Conyza stricta Willd. is being a newly emerging weed of barley-based cropping systems in response to conservational tillage practices. Seed germination ecology of four populations (irrigated, rainfed, abandoned and ruderal habitats) was studied in laboratory and greenhouse experiments. The presence/absence of seed dormancy was inferred first, which indicated seeds were non-dormant. Seed germination was then recorded under various photoperiods, constant and alternating day/night temperatures, and pH, salinity and osmotic potential levels. Seedling emergence was observed from various seed burial depths. Seeds of all populations proved photoblastic and required 12-hour light/dark period for germination. Seeds of all populations germinated under 5–30°C constant temperature; however, peak germination was recorded under 17.22–18.11°C. Nonetheless, the highest germination was noted under 20/15°C alternating day/night temperature. Ruderal and irrigated populations better tolerated salinity and germinated under 0–500 mM salinity. Similarly, rainfed population proved more tolerant to osmotic potential than other populations. Seeds of all populations required neutral pH for the highest germination, whereas decline was noted in germination under basic and alkaline pH. Seedling emergence was retarded for seeds buried >2 cm depth and no emergence was recorded from >4 cm depth. These results add valuable information towards our understanding of seed germination ecology of C. stricta. Seed germination ability of different populations under diverse environmental conditions suspects that the species can present severe challenges in future if not managed. Deep seed burial along with effective management of the emerging seedlings seems a pragmatic option to manage the species in cultivated fields. However, immediate management strategies are needed for rest of the habitats.

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Root Growth of Neighboring Maize and Weeds Studied with Minirhizotrons

Weed Science ◽

10.1614/ws-d-12-00120.1 ◽

2013 ◽

Vol 61 (2) ◽

pp. 319-327 ◽

Cited By ~ 1

Author(s):

Deborah Britschgi ◽

Peter Stamp ◽

Juan M. Herrera

Keyword(s):

Root Growth ◽

Surface Area ◽

Plant Density ◽

Fluorescent Protein ◽

Root Density ◽

Weed Species ◽

Belowground Competition ◽

Higher Plant ◽

Common Lambsquarters ◽

Redroot Pigweed

Competition between crops and weeds may be stronger at the root than at the shoot level, but belowground competition remains poorly understood, due to the lack of suitable methods for root discrimination. Using a transgenic maize line expressing green fluorescent protein (GFP), we nondestructively discriminated maize roots from weed roots. Interactions between GFP-expressing maize, common lambsquarters, and redroot pigweed were studied in two different experiments with plants arranged in rows at a higher plant density (using boxes with a surface area of 0.09 m2) and in single-plant arrangements (using boxes with a surface area of 0.48 m2). Root density was screened using minirhizotrons. Relative to maize that was grown alone, maize root density was reduced from 41 to 87% when it was grown with redroot pigweed and from 27 to 73% when it was grown with common lambsquarters compared to maize grown alone. The calculated root : shoot ratios as well as the results of shoot dry weight and root density showed that both weed species restricted root growth more than they restricted shoot growth of maize. The effect of maize on the root density of the weeds ranged from a reduction of 25% to an increase of 23% for common lambsquarters and a reduction of 42 to 6% for redroot pigweed. This study constitutes the first direct quantification of root growth and distribution of maize growing together with weeds. Here we demonstrate that the innovative use of transgenic GFP-expressing maize combined with the minirhizotron technique offers new insights on the nature of the response of major crops to belowground competition with weeds.

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Enzyme der Vakuolen aus Wurzelzellen von Maiskeimlingen. Ein Beitrag zur funktionellen Bedeutung der Vakuole bei der intrazellulären Verdauung

Zeitschrift für Naturforschung B ◽

10.1515/znb-1966-0913 ◽

1966 ◽

Vol 21 (9) ◽

pp. 871-878 ◽

Cited By ~ 41

Author(s):

Ph. Matile

Keyword(s):

Cytochrome C ◽

Alanine Aminotransferase ◽

Hydrolytic Enzymes ◽

Plant Cells ◽

Mitochondrial Enzymes ◽

Centrifugal Field ◽

Higher Plant ◽

Cytochrome C Reductase ◽

Intracellular Digestion

The isolation of vacuoles from rootlets of corn seedlings based on the slicing and chopping of the plasmolized tissue is described. The isolated vacuoles have densities higher than 1,029 g cm-3; in the centrifugal field they rapidly move centripetally if the extracts are brought to a density of 1,185 g cm-3 by the addition of 30% of “Urografine”. Thus a simple separation of isolated vacuoles from the extracts could be achieved.The following hydrolytic enzymes have been localized in isolated vacuoles: protease, RNase, DNase, phosphatase and two different unspecific esterases. Furthermore two transaminases, aspartate and alanine-aminotransferase and two oxyreductases cytochrome-c-reductase and diaphorase are present in preparations of isolated vacuoles. The absence of mitochondrial enzymes and of enzymes known to be localized in the groundplasm indicated the purity of the preparations of vacuoles.It is concluded that the vacuoles of higher plant cells represent organelles in which the processes of intracellular digestion take place.

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Influence of Weed Control Programs in Intensive Cropping Systems

Weed Science ◽

10.1017/s0043174500059956 ◽

1984 ◽

Vol 32 (6) ◽

pp. 762-767 ◽

Cited By ~ 6

Author(s):

N. C. Glaze ◽

C. C. Dowler ◽

A. W. Johnson ◽

D. R. Sumner

Keyword(s):

Weed Control ◽

Cropping Systems ◽

Weed Species ◽

Multiple Cropping ◽

Control Programs ◽

Yellow Nutsedge ◽

Herbicide Treatments ◽

Intensive Cropping ◽

Main Effects ◽

Herbicide Programs

Six multiple-cropping systems composed of: a) turnip (Brassica campestrisspp.rapifera), corn (Zea maysL.), and snapbean (Phaseolus vulgarisL.); b) turnip, peanut (Arachis hypogaeaL.), and snapbean; c) turnip, corn, and turnip; d) turnip, peanut, and turnip; e) snapbean, soybean [Glycine max(L.) Merr.], and cabbage (Brassica oleraceaL.); and f) turnip, cucumber (Cucumis sativusL.), cowpea [Vigna unguiculata(L.) Walp.], and turnip were subjected to nematicide and weed control programs of cultivation or herbicides. Herbicide programs were superior to cultivation in control of weeds. Weeds remaining in the row following cultivation competed severely with crops. Weed species remaining were altered depending on the method of control and crop. Yellow nutsedge (Cyperus esculentusL. ♯3CYPES) increased rapidly in all herbicide programs but not in cultivated plots. Pigweeds (Amaranthusspp.) were controlled by herbicides but increased in cultivated plots. Corn, peanut, soybean, and spring snapbean yields were higher in herbicide treatments than in cultivated treatments. Cucumber was the only crop that had increased yields for both main effects, herbicide and nematicide. Turnip was consistently injured in herbicide treatments, which was believed to be caused by residues from previous crops interacting with pathogens and possible allelopathic effects of decaying organic matter.

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