Critical period of competition between weeds [mainly Bromus rigidus] and durum wheat (Triticum durum) in Sais of Morocco | Caracterisation de la periode critique de competition entre le ble dur (Triticum durum Desf.) et une communaute d'adventices dominees par le brome (Bromus rigidus Roth.) dans le Sais Maroc
1996
Hamal, A. | Bouhache, M. (INRA, Meknes (Morocco). Lab. de Malherbologie) | Rzozi, S.B.
A field study was conducted at the experimental station of the National School of Agriculture, Meknes. The objective was to characterize the critical period of competition between weeds and durum wheat in the Sais region. Different weed competition and weed-free durations extending from crop emergence to tillering, elongation, heading, flowering and maturity, were compared. Plots were highly infested by weeds. Although 28 species were identified with a prevalence of broad-leaves (82 per cent) and annual species (76 per cent), Bromus rigidus Roth was predominating on the basis of density (87 per cent) and biomass (72 per cent). Yield analysis indicated that the critical period varied with the amount of yield losses tolerated. For 5 per cent yield loss, wheat had to be weed-free from emergency to twenty five days after flowering. For 10 per cent yield loss, wheat had to be weed-free from emergency to sixteen days after heading. For 15 per cent yield loss, wheat had to be weed-free from emergency to heading. Water use efficiency for grain and biological yield of wheat was 10.1 and 43.8 kg per ha per mm, respectively. Weeds absorbed more water than wheat, increasing evapotranspiration at tillering and reducing water use efficiency for grain yield by 64 and 61 per cent, respectively. If weeds were not controlled for the entire growing season, yield loss was 66.7 per cent, compared to weed-free check (40.2 qls per ha). Weed control from crop emergence to elongation or heading, allowed a yield gain of 130 per cent and 149 per cent, respectively compared to weedy check
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