ROSE ROOTSTOCK BREEDING FOR SALINITY TOLERANCE
Since practically no commercial rose rootstocks have genetic variability because they are vegetatively propagated (by cuttings or apomictic seeds), the BFA of Ahrensburg developed an interspecific multiflora-type hybrid by crossing 2n R. multiflora x 4n R. hybrida. To select resistent genotypes salt stress was induced irrigating 2–3 month old seedlings with solutions of 20 mM 1-1 NaCl or NaHCO3 added to normal irrigation water (0.4 dS m-1). A wide variability in salt tolerance and a high correlation between responses to both treatments were found in the population tested. The data presented show that survival ability after pruning of salt-stressed plants was an efficient screening technique. Best selected plants are being interpollinated to produce improved seed progenies, but no significant differences in resistance levels have been found between the parent material and first generation offspring.
Cuttings propagation capacity was good for all the plants tested. Specific budding trials using cvs. Mercedes and Ilseta showed excellent rootstock-scion compatibility. Evaluation of selected rootstocks' capacity to reduce salt damage when grafting with sensitive cultivars and field trials to test behaviour in winter production have been started.