Is rootstock-induced dwarfing in olive an effect of reduced plant hydraulic efficiency?
We investigated the hydraulic architecture of young olive trees either self-rooted or grafted on rootstocks with contrasting size-controlling potential. Clones of Olea europea L. (Olive) cv 'Leccino' inducing vigorous scion growth (Leccino 'Minerva', LM) or scion dwarfing (Leccino 'Dwarf', LD) were studied in different scion/rootstock combinations (LD, LM, LD/LD, LM/LM, LD/LM and LM/LD). Shoots growing on LD root systems developed about 50% less leaf surface area than shoots growing on LM root systems. Root systems accounted for 60-70% of plant hydraulic resistance (R), whereas hydraulic resistance of the graft union was negligible. Hydraulic conductance (K = 1/R) of LD root systems was up to 2.5 times less than that of LM root systems. Total leaf surface area (A(L)) was closely and positively related to root hydraulic conductance so that whole-plant hydraulic conductance scaled by A(L) did not differ between experimental groups. Accordingly, maximum transpiration rate and minimum leaf water potential did not differ significantly among experimental groups. We conclude that reduced root hydraulic conductance may explain rootstock-induced dwarfing in olive.
Nardini
Andrea
A
Dipartimento di Biologia, Università di Trieste, Via L. Giorgieri 10, 34127 Trieste, Italia. nardini@units.it
Gascó
Antonio
A
Raimondo
Fabio
F
Gortan
Emmanuelle
E
Lo Gullo
Maria A
MA
Caruso
Tiziano
T
Salleo
Sebastiano
S
D001692:Biological Transport / Q000502:physiology; D031658:Olea / Q000254:growth & development* / Q000502:physiology*; D018515:Plant Leaves / Q000033:anatomy & histology / Q000502:physiology; D018517:Plant Roots / Q000502:physiology*; D013997:Time Factors; D014867:Water / Q000502:physiology*
D014867:Water