Ecologically-based weed management through intercropping

Majid Aghaalikahni

Agronomy Department

Tarbiat Modares University

I. BARLEY / RAPESEED

II. BARLEY / GRASSPEA

III. BARLEY / CHICKPEA

IV. SWEET CORN / MUNGBEAN

I. BARLEY / RAPESEED

II. BARLEY / GRASSPEA

III. BARLEY / CHICKPEA

IV. SWEET CORN / MUNGBEAN

Outline for the main project:

Title of current presentation : Barley/chickpea intercropping as an

environmentally- sound tool for weed management in small scale dry land farms

I. Conventional management

Agricultural production systems in many parts of the world have shifted from relatively small-scale polycultures to large-scale continuous monocultures.

I. Conventional management

This shift in agriculture has been driven by advances in breeding and chemical technologies that occurred after World War II.

I. Conventional management

These technologies have allowed growers to manage weeds and crop fertility chemically rather than mechanically (i.e. not reliant on hand pulling and hoeing)

I. Conventional management

Now, with the appropriate fertilizers and pesticides and equipment growers can plant the same crop over a large area, year after year

But we have to know:

Herbicides are the main (sometimes only) method of weed management in these systems. In this way, herbicide applications can be thought of as “large hammers”.

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Potential problems of the conventional management :

1 .Cropping-systems have been greatly simplified (i.e. lower diversity).

2 .Continuous cropping presents weeds with a “predictable” environment weeds with biology similar to crop are particularly difficult to control

3 .Large hammers evidently don’t work– we still have weed problems!

4 .Large hammers select for resistance

5 .As more weed species develop resistance, new herbicides must be developed….weeds will eventually develop resistance to these too!

6 .Synthetic pesticides and fertilizers can have unintended environmental effects*

*This last point, in particular, has driven much of the current desire/pressure to develop more ecologically-based weed and crop management strategies

Food web

What is the Main strategy in Ecologically-based weed management?

increasing cropping-system diversity

Why......?Because greater cropping-system diversity may increase the potential for ecological interactions to regulate pest populations, potentially decreasing the need for intensive chemical use.

How might one increase cropping-system diversity?

COVER CROPSCOVER CROPS

CROP ROTATIONCROP ROTATION

INTER-CROPPINGINTER-CROPPING

FIELD MARGINS/ HEDGE ROWSFIELD MARGINS/ HEDGE ROWS

WEEDY STRIPSWEEDY STRIPS

LAND-SCAPE LEVEL DIVERSITYLAND-SCAPE LEVEL DIVERSITY

Research hypothesis:

• A major concern for farmers growing grain legumes in low-input systems is their weak competitive ability toward weeds.

• Light, water and nutrient may be more completely absorbed and converted to crop biomass by INTERCROPPING.

• Barley and chickpea have different competitive ability for growth factors.

• They not compete for the same ecological niches.

• Interspecies competition is weaker than intraspecific competition for a given factor.

• Grain legumes / cereal INTERCROPPING may provide an ecological method utilizing competition and natural regulation mechanisms reduce the need for chemical fertilizer and to manage weeds with less use of herbicides.

Methods and Materials

Location: KARAJAlborz Province(representing a semi-arid climate)

Altitude: 1321 m

Latitude: 35 49 َ N

Longitude: 51 50 َ E

Precipitation: 243 mm

Soil texture : loam

agricultural research station of Tehran University (Karaj campus)

Soil chemical properties

Mnmg/kg

Znmg/kg

Femg/kg

Mgmeq/lit

O. M% K

mg/kg Pmg/kg

N%

Cameq/lit

Nameq/lit

SAR%

ECds/m

pHعمق نمونه

8.5 1.2 6.5 3.2 1.17 183 8.9 0.62 2.25 1.13 75 0.6 7.8 0-30

EXPERIMENTAL TREATMENTS factorial of chickpea × Barley mixing ratio as follow

ChickpeaBarley

50, 75, and 100 percent of pure stand

50, 75, and 100 percent of pure stand

plus two control plots (pure stand of chickpea and barley, 80 and 160 kg/ha respectively)

Treatments were arranged in a randomized complete blocks design with 3 replications .

BARLEY (Hordeum vulgare cv.Valfajr)

160 kg/ha

CHICKPEA (Cicer arietinum cv.4322)

80 kg/ha

Measured traits:

Weed biomass Weed species frequency Crops dry matter in pure stand and intercropped treatment

RESULTS and DISCUSSION

Weed diversity in our experiment

Commom name Scientific name Family

Fumitory Fumaria asepala Fumariaceae

Field bind weed Convonvulus arvensis Convolvulaceae

Common lamb. Squarters, Fathen Chenopoduim album Chenopodiaceae

Prostrate knot weed Polygonum aviculare Polygonaceae

Raphistre, Turnip weed Rapistrum rugosum Brassicaceae

Russian knap weed Acroptilon repens Asteraceae

Hypecum Hypecum pendulum Papaveraceae

Goldbachia Goldbachia laevigata Brassicaceae

Fumaria asepala(Fumariaceae)

Convolvulus arvensis (Convolvulaceae)

Chenopodium album (Chenopodiaceae)

Polygonum avicular (Polygonaceae)

Rapistrum rugosum (Brassicaceae)

Acroptylon repens (Astearaceae)

Goldbachia laevigata (Brassicaceae)

RELATIVE FREQUENCY OF WEED

1 .Chikpea monoculture has the highest weed density2.It was was dominantly consisted of fumitory

3 .Barley pure stand was kept weed free4 .All additive intercropped treatment reduced weed frequency

significantly5 .All weed species were suppressed in intercrop treatments

except fumitory which was alive up to flowering stage .

WEED BIOMASS1.The highest amount of weed biomass (620 kg/ha) were

obtained in chickpea monoculture.

2 .Green biomass of chickpea pure stand (220 Kg/ha) suppressed by weed competition .

3 .All experimental units including barley, significantly reduced weed biomass.

4 .It could be attributed to high growth rate and better establishment of barley comparing to chickpea.

5 .It could be concluded that barley has acceptable competition ability against weeds.

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barley(B) and chickpea© mixing ratio

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Damavand peak, 5619 masl (Alborz chain of mountains)

Tehran- Iran

Thank you for your attention

Efharisto’ poli’

Mean comparison of forage dry biomass for barley/chickpea intercropping

Treatment Chickpea dry matter (Kg/ha)

Barley dry matter(Kg/ha)

Total dry matter(Kg/ha )

C100B100 64.9bc 2916.16ab 2981.06ab

C100B75 64.26bc 1693.1cd 1757.4c

C100B50 82.93b 1828.61cd 1911.55c

C100 220.1a 0.0c 220.1d

C75B100 13.78d 2137.33bc 2151.12bc

C75B75 21.36cd 2077.5bc 2098.8bc

C75B50 79.95b 1451.83d 1531.8c

C50B100 12.76d 2554.7ab 2567.7ab

C50B75 7.183d 2136.9bc 2144.1bc

C50B50 33.23cd 1693.9cd 1726.6c

B100 0.0d 3056.33a 3056.33a