ABSTRACT

This chapter reports on the inheritance of herbicide resistance in weed species and demonstrates how genetic studies have provided, or could have provided, information on the appearance and mechanisms of resistance. It focuses on the origin and dynamics of resistance genes, provides additional information on how resistance has appeared in plants and populations. The chapter considers a large amount of genetic data on resistance to triazine herbicides. It focuses on quantitative inheritance, concerns herbicides which inhibit growth, rather than cause mortality. It describes the cases of resistance that fit simple Mendelian inheritance for weeds and crops. The chapter discusses the accuracy of methodology. It is concerned with the origin of resistance genes and their frequency and behavior in populations. The association of a given isozyme pattern with the ability to produce a higher frequency of mutants in each region is likely to involve other traits apart from triazine-resistance.