Management of weed crops in Angola. Case studies - maize and potatoes in Huambo highlands

Doutoramento em Engenharia Agronómica - Instituto Superior de AgronomiaThe main objectives of the studies carried out in three locals (Bailundo, Calenga and Chianga) were the weed identification and the study of the critical periods for weed management on potatoes and maize in the rainy and dry season. The effects of the interaction weeds x fertilization on crop yield was also determined. The varieties (imported and regional ones) response to nitrogen (maize) and phosphorus (potatoes) and its pest and diseases susceptibility was previously studied. Weed composition and biological types are presented. In maize the critical period varied with local and crop growing season, with a 95% weed-free total yield, the onset was 16 and 20 days after crop emergence (DAE) and ended between 45 and 60 DAE. In potatoes, the critical period varied with only crop growing season, the onset was at 26 DAE and ended between 66 and 61 DAE in the rainy and season, respectively.The effects of weed interference throughout the growth of maize and potatoes reduced crop yields ca. 90%. The interaction between fertilization and timely weed control showed a positive effect on yield, either in potatoes either in maize. The main objectives of the studies carried out in three locals (Bailundo, Calenga and Chianga) were the weed identification and the study of the critical periods for weed management on potatoes and maize in the rainy and dry season. The effects of the interaction weeds x fertilization on crop yield was also determined. The varieties (imported and regional ones) response to nitrogen (maize) and phosphorus (potatoes) and its pest and diseases susceptibility was previously studied. Weed composition and biological types are presented. In maize the critical period varied with local and crop growing season, with a 95% weed-free total yield, the onset was 16 and 20 days after crop emergence (DAE) and ended between 45 and 60 DAE. In potatoes, the critical period varied with only crop growing season, the onset was at 26 DAE and ended between 66 and 61 DAE in the rainy and season, respectively.The effects of weed interference throughout the growth of maize and potatoes reduced crop yields ca. 90%. The interaction between fertilization and timely weed control showed a positive effect on yield, either in potatoes either in maize