Critical crop-weed competition - A pivotal factor for annual planning of weed pest management towards sustainable crop productivity

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

Download Full-text

Application of electrical capacitance measurement for in situ monitoring of competitive interactions between maize and weed plants

Spanish Journal of Agricultural Research ◽

10.5424/sjar/2016142-7562 ◽

2016 ◽

Vol 14 (2) ◽

pp. e0904 ◽

Cited By ~ 3

Author(s):

Imre Cseresnyés ◽

Tünde Takács ◽

Anna Füzy ◽

Krisztina R. Végh ◽

Éva Lehoczky

Keyword(s):

Intraspecific Competition ◽

Belowground Biomass ◽

Dry Mass ◽

In Situ Monitoring ◽

Capacitance Measurement ◽

Weed Competition ◽

Electrical Capacitance ◽

Regular Measurement ◽

Crop Weed Competition

Applicability of root electrical capacitance (EC) measurement for monitoring of crop–weed competition was studied in a pot experiment. Maize (Zea mays L.) was grown both alone and with Echinochloa crus-galli or Abutilon theophrasti in different densities with regular measurement of root EC. Plants were harvested 42 days after planting to determine above- and belowground biomass. Depending on weed density, E. crus-galli-A. theophrasti interaction reduced the root EC of maize by 22–66% and 3–57%, respectively. Competitive effect of crop on weeds and intraspecific competition among weeds could also be detected by EC values: E. crus-galli was less sensitive both to the presence of maize and to intraspecific competition than A. theophrasti. Strong linear correlations between root dry mass and root EC for crop and weeds (with R2 from 0.901 to 0.956) were obtained by regression analyses at the end of the experiment. EC monitoring informed us on the emergence time of competition: E. crus-galli interfered with maize root growth a week earlier then A. theophrasti, and increasing weed densities accelerated the emergence of competition. In conclusion, the simple, non-destructive EC method should be considered a potential in situ technique for pot studies on crop–weed competition, which may partially substitute the intrusive techniques commonly used in agricultural researches.

Download Full-text

CROP-WEED COMPETITION STUDIES IN FABA BEAN (Vicia faba L.) UNDER RAINFED CONDITIONS

Acta Agronomica Hungarica ◽

10.1556/aagr.49.2001.3.11 ◽

2001 ◽

Vol 49 (3) ◽

pp. 299-303 ◽

Cited By ~ 7

Author(s):

A. M. Tawaha ◽

M. A. Turk

Keyword(s):

Vicia Faba ◽

Faba Bean ◽

Yield Components ◽

Field Experiments ◽

Maximum Yield ◽

Weed Competition ◽

Growing Seasons ◽

Yield And Yield Components ◽

Vicia Faba L ◽

Crop Weed Competition

Field experiments were conducted during the two growing seasons of 1999 and 2000 at the research farm of the Jordan University of Science and Technology (JUST) to study the effect of the time of weed removal on the yield and yield components of faba bean (Vicia faba L.). Removing weeds from 25 to 75 days after crop sowing led to significantly larger yields than on plots which were not weeded. Maximum yield was obtained in both years when weeds were removed thrice at 25, 50 and 75 days after crop sowing.

Download Full-text

RGB Image-Derived Indicators for Spatial Assessment of the Impact of Broadleaf Weeds on Wheat Biomass

Remote Sensing ◽

10.3390/rs12182982 ◽

2020 ◽

Vol 12 (18) ◽

pp. 2982 ◽

Cited By ~ 1

Author(s):

Christelle Gée ◽

Emmanuel Denimal

Keyword(s):

Biomass Production ◽

Precision Agriculture ◽

Weed Management ◽

Vegetation Index ◽

Management Strategies ◽

Weed Competition ◽

Growth Stages ◽

Area Index ◽

Crop Weed Competition ◽

The Impact

In precision agriculture, the development of proximal imaging systems embedded in autonomous vehicles allows to explore new weed management strategies for site-specific plant application. Accurate monitoring of weeds while controlling wheat growth requires indirect measurements of leaf area index (LAI) and above-ground dry matter biomass (BM) at early growth stages. This article explores the potential of RGB images to assess crop-weed competition in a wheat (Triticum aestivum L.) crop by generating two new indicators, the weed pressure (WP) and the local wheat biomass production (δBMc). The fractional vegetation cover (FVC) of the crop and the weeds was automatically determined from the images with a SVM-RBF classifier, using bag of visual word vectors as inputs. It is based on a new vegetation index called MetaIndex, defined as a vote of six indices widely used in the literature. Beyond a simple map of weed infestation, the map of WP describes the crop-weed competition. The map of δBMc, meanwhile, evaluates the local wheat above-ground biomass production and informs us about a potential stress. It is generated from the wheat FVC because it is highly correlated with LAI (r2 = 0.99) and BM (r2 = 0.93) obtained by destructive methods. By combining these two indicators, we aim at determining whether the origin of the wheat stress is due to weeds or not. This approach opens up new perspectives for the monitoring of weeds and the monitoring of their competition during crop growth with non-destructive and proximal sensing technologies in the early stages of development.

Download Full-text

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

Renewable Agriculture and Food Systems ◽

10.1017/s1742170519000115 ◽

2019 ◽

Vol 35 (5) ◽

pp. 493-502 ◽

Cited By ~ 1

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.

Download Full-text

Weeds of Paddy Field at Kirtipur, Kathmandu

Scientific World ◽

10.3126/sw.v5i5.2665 ◽

1970 ◽

Vol 5 (5) ◽

pp. 100-106 ◽

Cited By ~ 5

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

Download Full-text