INK DISEASE RESISTANCE: SOME PRELIMINARY ELEMENTS FROM THE STUDY OF DIFFERENT CROSSES

Authors:	M. Ramos Guedes-Lafargue, G. Salesses
Keywords:	Castanea - Phytophthora spp. - Genetic improvement - Breeding for resistance
Abstract: A study was made on a series of hybrids involving the three chestnut species, i.e. C. sativa, C. crenata and C. mollissima, using a test to evaluate behaviour towards ink disease. A Phytophthora cinnamomi isolate was inoculated on stems of which the tip was cut off, either from young greenhouse-grown hybrids, or on excised stems of various genotypes from the orchard. Great variability was underscored at intra and interspecific levels. The behaviour study of different hybrids has yielded preliminary results involving the following factors: distribution of individuals according to necrosis length for the different crosses, variation in the frequency of resistant individuals (necrosis length below 50 mm) within each cross, comparison of individuals distribution according to necrosis length for 6 reciprocal crosses, comparison of hybrid distributions according to necrosis length in a factorial plan (3 x 3). These observations only constitute preliminary elements, as each cross was made and the hybrids tested only once at the seedling stage. A genetic analysis has to be developed from a diallel cross which is currently being carried out.
Full Text (PDF format, 367891 bytes) Citation Download Adobe Acrobat Reader (free software to read PDF files)