Integrated Weed Management Strategies Effects on Agronomic Performance of Rainfed and Irrigated Rice

摘要

Weeds cause significant production losses estimated at 25%in tropical countries and constitute main factor limiting rice production in Madagascar.This research,which was conducted at Anosibe-Ifanja(Antananarivo,Madagascar),aims to propose the most cost-effective weed management strategies for both irrigated and rainfed rice system to improve rice production.To make the management of these potential rice weeds effective,two cultural practices were tested as good agricultural and farmers’practices on two rice systems.A phytoecological study and a floristic inventory were carried out on test plots,followed by an economic profitability analysis of management strategies.In rainfed rice,a greater number of species were inventoried(42 species in 14 families)than in irrigated rice(37 species in 9 families).The most important families found in both systems were Poaceae and Cyperaceae.But in rainfed rice,two other families are also dominant:Fabaceae and Asteraceae.The study on weed management strategy showed that adoption of in-season and out-of-season tillage combined with regular weeding is effective for weed control in irrigated rice.As far as rainfed rice is concerned,improved farming practice by integrating in-season tillage with aerial ploughing combined with the use of pre-emergence herbicide pendimethalin is more cost-effective.This research has resulted in an in-depth knowledge of rice weeds and weed control strategies that are only feasible with mechanization or animal traction.