EFFECTS OF GRAFTING ON TRANSPIRATION, CO2 FIXATION AND GROWTH OF ROSEPLANTS (ROSA X HYBRIDA CVS ILSETA AND MERCEDES)

Reduced stomatal conductance and lower rates of transpiration were mea sured in one year old grafted plants of rose (Rosa X hybrida) cvs Merc edes and Ilseta as compared with non-grafted plants of the two cultiva rs. In spite of the decreased rate of transpiration, the rate of CO2 f ixation and the content of minerals in the leaves were not altered by the different scion/root combinations. The fresh weight of the flower buds in both cultivars was affected by the type of the understock used . The mean flower stem length and the average number of flowers per st em in one flowering cycle were only little affected by the understock. Selection of various rose cultivars for use as understocks is propose d.