Bastaard-necrose bij tarwe

Abstract

Hybrid necrosis in wheat was shown to be based on two complementary genes Ne 1 and Ne 2 . Variation in degree of necrosis proved to depend on multiple alleles. The existence of weak, moderate and strong alleles of Ne 1 and Ne 2 could be demonstrated. The degree of necrosis was shown to depend also on environment. Normally lethal plants could even produce seed under artificial environmental conditions.The author studied the sources of the necrosis genes and their distribution. The genotypes of wheat available were determined by test crosses while their origin was found where possible. The frequent use of certain carrier varieties as parents had contributed to the spread of necrotic genes.All wheat varieties, selections and species studied (about 500) were classified into 3 genotype classes (Ne 1 -carriers, Ne 2 -carriers, non-carriers) with indication of the strength of the necrosis gene. In designing a wheat-crossing programme a breeder could thus ascertain whether the first filial generation would become necrotic and usually also the allelic combination of the first filial generation.The occurrence of carrier and non-carrier lines in several varieties was shown to provide sometimes the possibility of avoiding necrosis