Micropropagation of Cherry Rootstocks: III. Correlations Between Anatomical and Physiological Parameters and Root Initiation

Easy-to-root ‘Colt’ showed cell divisions leading to root initials beginning within 2 days after exposure to auxin. By contrast, juvenile (i.e., 2-year-old seedling) rooting Mazzard (P. avium ) and invigorated (i.e., by co-culture) rooting ‘46-1 Mazzard’ required 4 and 5 days. Root initials appeared in the phloem parenchyma in ‘Colt’ and in the cambium region in both seedling Mazzard and invigorated ‘46-1 Mazzard’. Peroxidase activity (PA) was low in shoot tips of ‘Colt’, intermediate in juvenile Mazzard, and high in adult non-rooting ‘46-1 Mazzard’. In basal shoot tissue, PA activity was low in both ‘Colt’ and invigorated ‘46-1 Mazzard’ prior to root initiation, but increased sharply when root initiation started. The appearance of root initials was associated with an increase in intensity of anodic band A for isoperoxidase.