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SOME PHYSIOLOGICAL AND GENETIC ASPECTS OF PEACH/PLUM GRAFT INCOMPATIBILITY
Nevertheless, recent studies showed that two types of incompatibility occur among peach/plum combinations, which are different physiologically as well as genetically: peach grafted on Damas GF 1869 and peach grafted on myrobalan (P. cerasifera).
Nursery observations using interstocks showed that peach/myrobalan corresponds to classical physiological incompatibility whereas peach Damas GF 1869 incompatibility results from two components: the most important is physiological and the other mechanical.
The use of a compatible interstock allows the elimination of this mechanical component (Table II).
A previous genetic study (Salesses et Al Kai 1984) showed that incompatibility of peach on Damas GF 1869 results from the presence in peach cultivar, of at least two dominant alleles (I1 or I2) and that there is no linkage between incompatibility and nectarine characteristics (Table III).
Further analysis allowed to state precisely that the second case of incompatibility (peach/mirobalan) does not result from this genetic system (Table IV).
Present results (Table VI) obtained from a diallel mating system consisting of seven myrobalan clones do not allow to conclude about the genetic support of peach/myrobalan incompatibility: apparently it is neither monogenic nor simple bigenic.
Such genetic knowledge is very important in the development of hybridization programmes designed to create new rootstocks for peach.