Effect of cassava-legume intercropping systems on productivity and cassava insect pests population dynamics across three major agro-climatic zones of Sierra Leone

Abstract

Field trials were conducted in 2015/2016 and 2016/2017 cropping seasons in three agro-climatic zones of the country to evaluate the productivity and insect pests population dynamics of cassava as a response to spatial arrangement, plant architecture and cropping systems. The treatments consisted of seven cropping associations, two cassava architectures and two spatial arrangements. The study reveals that yield parameters of cassava were higher in cassava-soybean system at all locations. The number of marketable roots and forage yield were on average higher when the erect cassava variety was intercropped with the legumes using the 1 m x 1m spatial arrangement. On the other hand, root yield and canopy width were higher when the 2 m x 0.5 m spatial arrangement and the branched cassava architecture was used respectively. In general, yield parameters were higher at Segbwema expect for forage yield that was higher at Makeni. With respect to cassava insect pests, higher percentage incidences and severity scores were recorded on sole cassava and when the branched cassava variety was intercropped with legumes using the 2 m x 0.5 m spatial arrangement of cassava. In addition, cassava insect pests incidences were only observed at 6 MAP and 9MAP and were higher in Segbwema compared to the other locations. Thus, in order to improve productivity of cassava with low insect pest infestation, the erect cassava variety should be intercropped with soybean at a spatial arrangement of 1 m x 1 m.