Allelopathic Potential of Crop Residues for Weed Management in Wheat under Pakistan's Semi Arid Conditions

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  • Topic: Weed control, Crops, Yield
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  • Published : March 27, 2013
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Allelopathic potential of crop residues for weed management in wheat under semi-arid conditions of Pakistan

Muhammad Ashraf
Professor of Agronomy, PMAS-Arid Agriculture University, Rawalpindi, Pakistan. drashraf_150@yahoo.com

RATIONALE

• Rainfed Wheat- Main winter crop grown by about 80% of the farmers on residual soil moisture, received during monsoon1. • Weeds infestation- a major yield reducing factor (25-30%↓); • If weeds are controlled, crop yield can be enhanced by about 37%2. 1 Khaliq et al., 2007) 2 (Bibi et al., 2005). Cont…..

Existing Weed Control systems: • Traditional weed control methods (Hand weeding) are time consuming, weather dependent and labor intensive1 ; + Socio-economic issues:[small land holdings, family size =8, poverty, migration to cities]

• Herbicides use is limited in drylands + these are expensive with Environmental hazards2; Reduced Nutritive value of many crops 3 and Herbicide resistance4. 1 (Naveed et al., 2008) 2 (Mancini et al., 2008) 3 (Nazarko et al., 2003). Cont…..

• WM programs should focus on environmental safety along with benefits to the farmers. • Alternate weed management systems need to be developed aimed to control weeds and raise the income of resource-poor farmers (increased crop yields) without despoiling the natural resource base.

ALTERNATE WEED MANAGEMENT OPTIONS

• Allelopathy − a mechanism of plant interference1 is a natural, inexpensive, environmentally safe and an organic approach to control weeds and increase crop yields while conserving the ecosystem2. • Sorghum is highly allelopathic3 • Sorghum residue may be effectively used to manage some of the important weeds in rainfed wheat without affecting crop in semi-arid environment4. 1 (Weston, 2005) 2 (Inderjit and Duke, 2003) 1 (Weston and Duke, 2003) 2 (Inderjit and Duke, 2003) Cont…..

• Water Extracts of different plant parts have different allelopathic potential 1. • Sunflower – possessed weed suppression ability 2 . • The combination of two or more allelopathic aqueous extracts may act synergistically and cause more phyto-toxic effect on weeds 3. • Mixing and applying sunflower and sorghum residue water extract (WE) may increase the spectrum of phytotoxic effects and may result in synergistic phytotoxic influences on weeds growth. 1 (Ben-Hammouda, et al. 2001; Chung, et al., 2003; Roth et al., 2000) 2 (Bertholdsson, 2004; Singh et al., 2001 ) 3 (Duke et al., 2000; Cheema et al., 2010)

Cont…..

OBJECTIVES OF RESEARCH

Overall objective: Evaluate the use of allelopathic crop residue collected from summer crop plants grown under drought and mineral stress conditions for weed management in wheat in semi-arid areas of Pakistan: Specific Objectives: • Test water extracts (WE)of different plant parts of sorghum residue for weeds suppression in wheat. • Evaluate the effects of sorghum residue mulch and sorghum WE for weed management in wheat. • Investigate the influence of sole and combined sorghum and sunflower WE spray on weeds in wheat.

EXPERIMENTAL DETAILS

• Location: Three experiments were conducted at University Research Farm, PMAS-Arid Agriculture University, Rawalpindi, Pakistan (33o 46 N, 73o 08 E). / /

• ~500 m above the sea level • Experimental years: successive Rabi (winter) seasons from 2007-2010.

Cont…..

• Environmental Characterization:
Climate
Rainfall and ET o

200 160

Rainfall and ET0 (mm)

160
143

120 ETo 80 40 0 Oct Nov Dec Jan Feb Mar Apr Rain

140
121

Mean Monthly Rainfall (mm)

120 100 80
67

60 40
26

57

56

Sever Stress Period
27 21 7 15

39

43

20 0

Month Rainfall Distribution (1977-11)
Source: Soil and water conservation Research Institute, Chakwal, Pakistan

Growing Season Rainfall
Period Monthly rain (mm) Oct Nov Dec Jan Feb March April Total

2006-07 2007-08 2008-09 2009-10 Long-term Av. (1977-07)

0

42

30

0

166

147

14

20

7

15

27

39

56

43...
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