Abstract

The 20^th century is remarkable in terms of replacement of management practices and technologies in agricultural systems. One of the major ones, was the substitution of genetically heterogeneous varieties by highly inbreed or pure lines of hybrids. Such narrow genetic base in cropping field, together with the scaling up in cultivated area, allowed the creation of the vulnerability conditions, which facilitate the occurrence of epidemics or decrease in resilience. As a result, there were catastrophic yield drop in many places and times, associated with plant disease epidemics or adverse climatic events. To overcome that vulnerability, genetic variability can be increase by means of seed mixture, multiline or agroforestry systems, which can be used in combination with the agro ecological principles.