Professor of Agronomy, PMAS-Arid Agriculture University, Rawalpindi, Pakistan. email@example.com
• 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)
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.
• 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.
• Environmental Characterization:
Rainfall and ET o
Rainfall and ET0 (mm)
120 ETo 80 40 0 Oct Nov Dec Jan Feb Mar Apr Rain
Mean Monthly Rainfall (mm)
120 100 80
Sever Stress Period
27 21 7 15
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)