Yield stability of sole and intercropping systems in the Northeast of Brazil

Abstract

Yield stability was analyzed by computing the coefficients of variation and using the regression technique (an adaptation of the procedure frequently used to examine the stability of individual genotypes over a range of conditions). These procedures were used to analyze the yield stability of cassava (Manihot esculenta), maize (Zea mays), cotton (Gossypium hirsutum) and dry beans (Phaseolus vulgaris) under sole and intercropping systems, in Paraíba State, in the Northeast of Brazil. The coeffients of variation were always higher in monocropping than in intercropping for the four crops. Maize and dry beans had the same slopes, while the coefficients of regression in cassava and cotton were higher than one for sole crops and statistically different from intercropping systems which had b values lower than 1 and hence were considered more stable. The advantage of intercropping in improving yield stability was more striking when the yields were negatively affected by the intercropping.