Henning and Alexander (1952, 1959) gave some evidence of physiological races existence in A. solani population. We started the investigation on A. solani variations in Bulgaria with relation to breeding for resistance. On the basis of the cultural and biological characteristics we distinguished 12 isolates in the wild population. In contrast to Henning and Alexander's investigation we took into account the attack on leaves (L) and on stem (S) as well. The reaction of the Lycopersicon species inoculated with different isolates pointed to a well expressed organotropic specialization and existence of 8 physiological races of A. solani in Bulgarian populations (Table 1). These results impose the usage of race mixture in screenings for A. solani resistance.
Table 1. Reaction of Lycopersicon sp. to A. solani isolates.
______________________________________________________________
Isolates
Species by PIGR* numbers______________________________________
3 4 7 11 12 17 19 227
______________________________________
L S L S L S L S L S L S L S L S
______________________________________________________________
L.esculentum 83602030***- -**- - - - - - - - - - + + - -
L. pimpinellif. 83602046- - + + - - - - - - - + + - - -
L. racemiger. 876100005 - - - - - - - - + + + + + - - -
L. humboldtii 87610003 - - - - - - - - - - - + + - - -
L. hirsutum 87610012 + - - - - - + + - - + + + + - -
L. hirs. glab. 87610013 + - - - - - + - - - + + + - - -
L. peruvianum 87610005 + - - - - - + + - - - + + + - -
L. chilense 87610011 + + + + - - + + + + + + + + + +
S . control + + + + + + + + + + + + + + + +
______________________________________________________________
*PIGR - Institute of Introduction and Plant Resources, Sadovo** - = Resistant
; + = Susceptible *** 83602030 is a primitive L. esculentumLiterature cited:
Henning, R. C. L. J. Alexander. 1959. Plant Dis. Reptr. 43, 298-308.