Weed diversity and frequency in coffee – grevilleas intercropping systems

Abstract

In Vitória da Conquista, Bahia, Brazil, intercropping with grevillea (Grevillea robusta A. Cunn) was implemented to reduce damage caused by wind speed in a coffee (Coffea arabica L.) plantation. As a consequence, many other factors, like reduction in solar radiation incidence, air temperature, soil moisture maintenance and increase in soil organic matter content were also observed. Such changes in the environment alters the number of plants and behaviour of coffee plants as well as other biotic components of this agroecosystem. This work deals with grevillea densities intercropped in coffee plantations and its relation to weed diversity and density. The experiment was carried out from April 2004 to March 2005 on six observation fields with different revile arrangements in coffee plantations (T1: 6x6m, T2 : 6x12m, T3: 12x9m, T4:9x9m, T5:9x18m, T6:18x18m) and a coffee field maintained in a full sunshine exposition (T7). Coffee crop spacing was one meter in row between plants and three meters between rows. Weed observations revealed 21 species; five Dicotyledons and 16 Monocotyledons. The highest weed diversity indexes were observed in fields with greater density of grevillea trees. Tree intercropping in coffee fields influenced weed density, frequency and diversity in comparison to coffee exposed to full sunshine.