scholarly journals Weeds of Paddy Field at Kirtipur, Kathmandu

1970 ◽  
Vol 5 (5) ◽  
pp. 100-106 ◽  
Author(s):  
Sailaza Manandhar ◽  
Bharat B Shrestha ◽  
Hari D Lekhak
Keyword(s):  
Grain Yield ◽  
Seedling Growth ◽  
Shoot Elongation ◽  
Weed Competition ◽  
Root Extract ◽  
Aqueous Extracts ◽  
Weed Species ◽  
Ageratum Conyzoides ◽  
Straw Yield ◽  
Crop Weed Competition

Paddy (Oryza sativa L. var. Taiching-127) fields of Kirtipur, central Nepal, were studied to evaluate the effects of weeds on crop yield during June to October 2003. Weed community was recorded in permanently marked plots (2 x 2 m2 each), and grain and straw yields were measured. The effect of aqueous extracts (2 to 10%) of leaf, stem and root of dominant weeds (Echinochloa colona, E. crusgalli, Cyperus iria and Ageratum conyzoides) on germination and seedling growth of the paddy (Taiching-127) was examined in the laboratory. Altogether 52 weed species (27 dicot and 25 monocot) belonging to 32 genera and 15 families infested the paddy. The maximum weed density was observed in September (105 pl/m2). There was significant reduction in straw and grain yield of paddy in weedy plots and negative correlation between weed species richness and straw yield. Crop weed competition reduced straw yield by 13% to 38% and grain yield by 25% to 47%. Weed growth changed pH and reduced soil nitrogen and phosphorus content. Aqueous extracts of root, stem and leaf of dominant weeds (Echinochloa colona, E. crus-galli, Cyperus iria and Ageratum conyzoides) showed a weak effect on seeds germination however most of them had inhibitory effect on root and shoot elongation of paddy seedlings. Root elongation was more sensitive to allelopathic inhibition than shoot elongation. Stem extract of these weeds showed higher inhibition on seedling growth of paddy than leaf and root extract except in Ageratum conyzoides in which root extract showed highest inhibition. Keywords: Allelopathy; Crop-weed competition; Soil nutrients; Germination; Grain yield. DOI: 10.3126/sw.v5i5.2665 Scientific World, Vol. 5, No. 5, July 2007 100-106

scholarly journals Impact of sowing methods and weed control practices on yield and economics of wet direct seeded rice

2021 ◽  
Vol 58 (3) ◽  
pp. 375-383
Author(s):  
BS Satapathy ◽  
B Duary ◽  
Sanjoy Saha ◽  
S Munda ◽  
D Chatterjee
Keyword(s):  
Field Experiment ◽  
Grain Yield ◽  
Weed Control ◽  
Direct Seeding ◽  
Weed Competition ◽  
Weed Species ◽  
Cyperus Difformis ◽  
Control Options ◽  
Direct Seeded ◽  
Crop Weed Competition

Wet direct seeding is proved as a viable alternate to conventional transplanting method of rice. Maintenance of optimum population by adopting an appropriate sowing method followed by judicious weed control practices ensures profitability of wet direct seeded rice (W-DSR). A field experiment was carried out to find out a suitable sowing technique and weed control options for enhancing productivity and economics of W-DSR. The W-DSR was infested with twelve numbers of weed species comprising of eight families under different sowing methods. The composition of sedges, broadleaved (BLW) and grassy weeds was 83.07, 11.0 and 5.93%, respectively. Irrespective of sowing methods, weeds such as, Echinochloa glabrescens and Leptochloa chinensis among grasses, Cyperus difformis and Scirpus juncoides among sedges and Lindernia anagallis among BLW were dominant. Drum seeding recorded 6.9 and 12.7% higher gross and net return, respectively than broadcasting, but it was at par with spot seeding. Highest B: C ratio of 2.07 was recorded with drum seeding, whereas spot seeding recorded lowest B: C ratio (1.99). Crop-weed competition caused 31.7% reduction in grain yield with W-DSR. Application of early post-emergent herbicide bensulfuron-methyl + pretilachlor @ 60+600 g/ha at 10 DAS, azimsulfuron @ 35 g/ha at 20 DAS, and bispyribac sodium @ 30 g/ha at 20 DAS recorded increase in grain yield 40.3, 40.1 and 39.8%, respectively over the weedy check. Ready mix bensulfuron-methyl + pretilachlor @ 60+600 g/ha at 10 DAS registered highest B: C ratio (2.16) but it did not vary significantly with bispyribac sodium @ 30 g/ha and azimsulfuron @ 35 g/ha.

scholarly journals Interference of Broadleaf Buttonweed and White-Eye in Soybean

2020 ◽  
Vol 38 ◽  
Author(s):  
F. DIESEL ◽  
M.M. TREZZI ◽  
M. GALLON ◽  
P.H.F. MIZERSKI ◽  
S.C. BATISTEL ◽  
...  
Keyword(s):  
Grain Yield ◽  
Yield Loss ◽  
Block Design ◽  
Grain Weight ◽  
Weed Competition ◽  
Yield Losses ◽  
Weed Species ◽  
Randomized Block Design ◽  
Crop Weed Competition ◽  
1000 Grain Weight

ABSTRACT: Weed species is one of the factors contributing to grain yield losses due to crop-weed competition. Two of the most common weeds of soybean fields in Brazil are from the Rubiaceae family: Borreria latifolia and Richardia brasiliensis. This study aimed to evaluate the effects of B. latifolia and R. brasiliensis on plant development, yield components, and soybean productivity. Two assays were conducted in a randomized block design with four replications, using a two-level factorial design, in which the first factor consisted of the species B. latifolia and R. brasiliensis and the second factor consisted of the densities 0, 2, 4, 6, 8, 10, and 12 plants m-2. Plant height, leaf area and total chlorophyll in the V6 and R5 stages, number of pods per plant, number of grains per pod, 1000-grain weight, and grain yield loss were evaluated in both cultivars. Grain yield of both soybean cultivars was negatively affected by the interference with B. latifolia and R. brasiliensis. The species B. latifolia was more competitive with soybean when compared to R. brasiliensis, causing higher reductions for all variables. Each B. latifolia plant per square meter is able to reduce the yield of soybean by 3 a 4.4%, while each R.brasiliensis plant reduces yield by 2 a 2.6%. For both species, the reduction in soybean yield due to competition was caused by a decrease in the number of pods per plant, number of grains per pod, and 1000-grain weight.

scholarly journals Effect of duration of weed competition and weed control on the yield of Indian spinach

1970 ◽  
Vol 33 (4) ◽  
pp. 623-629 ◽  
Author(s):  
MSA Khan ◽  
MA Hossain ◽  
M Nurul Islam ◽  
SN Mahfuza ◽  
MK Uddin
Keyword(s):  
Weed Management ◽  
Critical Period ◽  
Field Experiments ◽  
Agricultural Research ◽  
Cyperus Rotundus ◽  
Weed Competition ◽  
Weed Species ◽  
Maximum Benefit ◽  
Hand Weeding ◽  
Crop Weed Competition

Field experiments were conducted at the research farm of Bangladesh Agricultural Research Institute, Joydebpur during kharif-1 (March to July) seasons of 2005 and 2006 to identify the critical period of crop-weed competition for Indian spinach. Major weed species were Paspalurn commersoni, Echinochlaa crusgalli. Lie nv/nc india. Cyanotis axillaris and Cyperus rotundus. The lowest weed dry matter was 76.3 g m-2 in 2005 and l01.60 g m-2 in 2006 from the plots weeded up to 40 days after transplanting (DAT). The highest yields were obtained (74.82 t ha in 2005 and 48.48 t ha in 2006) from the weed free plots. The fresh yield of Indian spinach did not vary among no weeding upto 20, 30 and 40 DAT in 2006. But weeded plot upto 30 and 40 DAT produced identical yield in 2005. Maximum BCR (4.52) was obtained from weeded plots upto 30 DAT in 2005 but BCR (2.60) was same from weeded upto 30 and 40 DA F in 2006. On an average, highest BCR (3.55) was recorded from weeding upto 30 DAT. Results revealed that the critical period of crop weed competition lies between 20 and 30 DAT and two times hand weeding would be necessary within 30 DAT for maximum benefit. Key Words: Crop-weed competitions, critical period, weed management and Indian spinach. doi: 10.3329/bjar.v33i4.2306 Bangladesh J. Agril. Res. 33(4) : 623-629, December 2008

scholarly journals ALLELOPATHIC EFFECT OF A WEED SPECIES, CYPERUS ROTUNDUS L. AND CLEOME VISCOSA L. ON GROWTH AND DEVELOPMENT OF BLACK GRAM (VIGNA MUNGO (L.) HEPPER.)

2015 ◽  
Vol 2 (2) ◽  
pp. 123-128
Author(s):  
Prabhakaran J ◽  
Kavitha D ◽  
Arumugam K
Keyword(s):  
Seedling Growth ◽  
Vigna Mungo ◽  
Cyperus Rotundus ◽  
Allelopathic Effect ◽  
Aqueous Extracts ◽  
Black Gram ◽  
Weed Species ◽  
Weight Content ◽  
Whole Plants ◽  
Cleome Viscosa

The present study was aimed to investigate the allelopathic influence of two weed species Cyperus rotundus L. and Cleome viscosa L. against the growth of Black gram (Vigna mungo (L.) Hepper). Aqueous extracts (5%, 10%, 25%, 50%, 75% and 100% concentrations) of whole plants of C. rotundus and C. viscosa were employed to investigate their influence on the germination and seedling growth of the black gram. The aqueous whole plants extracts ( from 5% to 100% concentrations) of C. rotundus and C. viscosa exhibited an inhibitory effects on all the parameters employed in the germination percentage, root and shoot growth, fresh and dry weight, content of chlorophyll, starch, sugar and protein contents of Black gram over control. The extracts of both the weeds caused a minimum inhibition on germination and seedling growth of Black gram at 5% concentration and the intensity of inhibition increased when increased extract concentrations. The aqueous extracts of C. rotundus and C. viscosa showed an inhibitory effect on Black gram but their effect was more severe on black gram by the extract treatments of C. rotundus than that of C. viscosa.

scholarly journals Allelopathic potential of mustard crop residues on weed management and performance of transplant Aman rice

2017 ◽  
Vol 15 (2) ◽  
pp. 133-139
Author(s):  
MN Hossain ◽  
MR Uddin ◽  
UK Sarker ◽  
S Ferdousi ◽  
MJ Uddin
Keyword(s):  
Grain Yield ◽  
Weed Management ◽  
Crop Residues ◽  
Block Design ◽  
Crop Productivity ◽  
Weed Species ◽  
Allelopathic Potential ◽  
Straw Yield ◽  
Percent Inhibition ◽  
Mustard Crop

Crop allelopathy may be useful to minimize serious problems in the present agricultural production such as environmental pollution, unsafe production, human health concerns, depletion of crop diversity, soil sickness and reduction of crop productivity. In this phenomenon an experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh to evaluate the effect of crop residues of mustard on weed management and crop performance of T. aman rice. The experiment consisted of three cultivars of T. aman rice viz., BR11, BR23 and BRRI dhan49 and five different level of mustard crop residues such as no crop residues, mustard crop residues @ 0.5, 1.0, 1.5 and 2.0 t ha–1. The experiment was laid out in a randomized complete block design with three replications. Five weed species belonging to three families infested the experimental plots. Weed population, weed dry weight and percent inhibition of weed were significantly influenced by mustard crop residues and cultivar. The maximum weed growth was noticed with the cultivar BR23 and the minimum was found in the cultivar BR11. The grain yield as well as the other yield contributing characters produced by BR11 was the highest among the studied varieties. The highest percent inhibition of 71.17, 69.19, 80.88, 70.48 and 86.97 was in Shama (Echinochlo acrusgalli), Panishapla (Nymphaea nouchali), Panichaise (Scirpus juncoides), Panikachu (Monochoria vaginalis) and Susnishak (Marsilea quadrifolia), respectively which was caused by the application of mustard crop residues @ 2 t ha–1. The highest loss of grain yield was obtained where no crop residues were incorporated. The highest numbers of tillers hill-1, numbers of grains panicle–1, 1000-grain weight, grain yield, straw yield were observed where mustard crop residues were incorporated @ 2.0 t ha–1. BR11 cultivar with all treatments produced the highest grain and straw yield among the treatment combination. The results of this study indicate that different amount of mustard crop residues showed potential activity to suppress weed growth.J. Bangladesh Agril. Univ. 15(2): 133-139, December 2017

scholarly journals Green manure and phosphorus fertilization affect weed community composition and crop/weed competition in organic maize

2019 ◽  
Vol 35 (5) ◽  
pp. 493-502 ◽  
Author(s):  
Stefano Carlesi ◽  
Federica Bigongiali ◽  
Daniele Antichi ◽  
Corrado Ciaccia ◽  
Fabio Tittarelli ◽  
...  
Keyword(s):  
Community Composition ◽  
Green Manure ◽  
Competitive Ability ◽  
Early Growth ◽  
Phosphorus Fertilization ◽  
Weed Competition ◽  
Weed Species ◽  
Green Manuring ◽  
Density And Biomass ◽  
Crop Weed Competition

AbstractGreen manure and compost-enriched in phosphorus can promote the sustainability of cropping systems by increasing soil fertility over the long term. They can also be used to manage crop/weed interactions, a key element in guaranteeing an appropriate level of satisfactory crop yields. We studied how green manuring with hairy vetch (Vicia villosaRoth.) and the application of different types of phosphorous-enriched compost affect weed/maize (Zea maysL.) interactions in an organic stockless Mediterranean agroecosystem for two consecutive dry years. Green manure stimulated the expression of maize traits related to a higher competitive ability against weeds, such as early growth, height and leaf area index, while the effect of compost was less clear. Regarding crop/weed competition, both green manuring and a phosphorus-enriched compost application gave a significant advantage to maize. Neither green manure nor compost increased total weed density and biomass compared to the control. Green manuring significantly affected the weed community composition. The relative density of ruderal and competitive-ruderal species (according to Grime's classification) was higher in plots where the green manure was applied. The use of green manure, together with novel composting techniques, significantly affected crop/weed competitive interactions, favoring maize, but also creating favorable conditions for unwanted weed species such as competitive-ruderals. Increasing nitrogen availability in the early growth stages of maize through green manuring can increase crop competitive ability. However, this may not suffice to preserve the system from future weed problems, should potentially detrimental species be selected. Dedicated strategies for the control of emerging weed species may thus be needed.

Modelling interactions between herbicide dose and multiple weed species interference in crop-weed competition

Weed Research ◽  
2006 ◽  
Vol 46 (2) ◽  
pp. 175-184 ◽  
Author(s):  
D S KIM ◽  
E J P MARSHALL ◽  
J C CASELEY ◽  
P BRAIN
Keyword(s):  
Weed Competition ◽  
Weed Species ◽  
Crop Weed Competition

scholarly journals Differential suppression of rice weeds by allelopathic plant aqueous extracts

2013 ◽  
Vol 31 (1) ◽  
pp. 21-28 ◽  
Author(s):  
A Khaliq ◽  
A Matloob ◽  
M.B Khan ◽  
A Tanveer
Keyword(s):  
Seedling Growth ◽  
Weed Management ◽  
Biomass Accumulation ◽  
Cyperus Rotundus ◽  
Interactive Effects ◽  
Aqueous Extracts ◽  
Weed Species ◽  
Test Species ◽  
Chlorophyll Contents ◽  
Species Specific

Herbicidal potential of different plant aqueous extracts was evaluated against early seedling growth of rice weeds in pot studies. Plant aqueous extracts of sorghum (Sorghum bicolor), sunflower (Helianthus annuus), brassica (Brassica compestris), mulberry (Morris alba), eucalyptus (Eucalyptus camaldunensis), and winter cherry (Withania somnifera) at a spray volume of 18 L ha-1 each at the 2-4 leaf stage of rice weeds viz horse purslane (Trianthema portulacastrum) [broad-leaf], jungle rice (Echinochloa colona), and E. crus-galli (barnyard grass) [grasses] and purple nut sedge (Cyperus rotundus) and rice flat sedge (C. iria) [sedges]. The results showed significant interactive effects between plant aqueous extracts and the tested weed species for seedling growth attributes depicting that allelopathic inhibition was species-specific. Shoot and root length, lateral plant spread, biomass accumulation, and leaf chlorophyll contents in test species were all reduced by different extracts. The study suggested the suppressive potential of allelopathic plant aqueous extracts against rice weeds, and offered promise for their usefulness as a tool for weed management under field conditions.

Effect of Weed Removal Timing and Row Spacing on Soil Moisture in Corn (Zea mays)

2006 ◽  
Vol 20 (2) ◽  
pp. 399-409 ◽  
Author(s):  
Caleb D. Dalley ◽  
Mark L. Bernards ◽  
James J. Kells
Keyword(s):  
Soil Moisture ◽  
Grain Yield ◽  
Soil Depth ◽  
Weed Competition ◽  
Row Spacing ◽  
Corn Yield ◽  
Weed Species ◽  
Common Lambsquarters ◽  
Weed Interference ◽  
Giant Foxtail

Glyphosate-resistant corn was grown in 38- and 76-cm row spacings at two locations in 2001 to examine the effect of weed competition and row spacing on soil moisture. Volumetric soil moisture was measured to a depth of 0.9 m in 18-cm increments. Glyphosate was applied when average weed canopy heights reached 5, 10, 15, 23, and 30 cm. Season-long weed interference reduced soil moisture compared with the weed free controls. At Clarksville, MI, where common lambsquarters was the dominant weed species, weed interference reduced soil moisture in the 0- to 18-cm soil depth from late June through early August and at the 54- to 72- and 72- to 90-cm depths from mid-July through the end of the season. At East Lansing, MI, where giant foxtail was the dominant weed species, weed interference reduced soil moisture at the 18- to 36-, 36- to 54-, and 54- to 72-cm soil depths from mid-June to the end of the season. Season-long weed competition reduced yields more than 90% at each location. Weeds that emerged after the 5-cm glyphosate timing reduced soil moisture and grain yield at both locations. Delaying glyphosate applications until weeds reached 23 cm or more in height reduced corn yield at both locations and soil moisture at East Lansing. Grain yields in the 10- and 15-cm glyphosate-timing treatments were equal to the weed-free corn, even though soil moisture was less during pollination and grain fill. Row spacing did not affect grain yield but did affect soil moisture. Soil moisture was greater in the 76-cm row spacing, suggesting that corn in the 38-cm row spacing may have been able to access soil moisture more effectively.

scholarly journals Allelopathic Interference of Ageratum conyzoides L. against Rice Varieties

2020 ◽  
pp. 69-76
Author(s):  
Bhawna Negi ◽  
S.S Bargali ◽  
Kiran Bargali ◽  
Kavita Khatri
Keyword(s):  
Seed Germination ◽  
Seedling Growth ◽  
Leaf Extract ◽  
Water Soluble ◽  
Allelopathic Effect ◽  
Aqueous Extracts ◽  
Ageratum Conyzoides ◽  
Leaf Extracts ◽  
Rice Varieties ◽  
Seedling Length

Ageratum conyzoides L. is an invasive weed that has severely infested cultivated lands and interferes with the growth of crops. In this study aqueous extracts of 50 and 100% concentration were prepared from fresh and air dried plant parts (Leaves and roots) of A. conyzoides and their allelopathic effect was observed on seed germination and seedling growth of two rice varieties namely Sava and Geru. In Sava variety, a significant reduction in seed germination, seedling length and dry weight was recorded under dry leaf extract while under fresh leaf extract seed germination and seedling length was increased at 50% concentration as compared to control. In Geru variety both fresh and dry leaf extracts resulted in decreased seed germination and seedling growth with increasing concentration. Similar patterns were recorded for fresh and dry root extracts. The inhibitory effect of leaf extracts was more pronounced than root extract and overall dry aqueous extracts of leaf and root were more inhibitory than fresh aqueous extracts. Among varieties, Sava was least affected as compared to the Geru. This study indicated that A. conyzoides exert allelopathic effect towards rice crop by releasing water soluble phytochemicals.

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