Eco-physiological evaluation of different scion-rootstock combinations of almond grown in Mediterranean conditions

Introduction. Recent management trends in almond orchards have focused on intensification and high-density plantings using Prunus rootstock cultivars with different vigor traits. This investigation aims to prospect precocious detection of adequate scion-rootstock combination for almond. Materials and methods. Five almond cultivars ('Tuono', 'Lauranne', 'Soleta', 'Belona' and 'Guara') grafted on three peach and plum based rootstocks of different degrees of vigor ('Garnem', 'Rootpac-40' and 'Rootpac-20') were trained in super high-density planting in an experimental orchard. Tree vigor, tree water status, leaf chlorophyll content and quantum yield of photosynthesis system II (PSII) were monitored over two budding seasons. Results and discussion. 'Garnem' and 'Rootpac-40' were respectively the most and the medium vigorous rootstocks and induced the best tree water status, chlorophyll content and quantum yield of PSII for the tested almond cultivars. Scions grafted on 'Garnem' had the highest values of trunk cross-sectional area (TCSA), and almond scions were higher on 'Garnem', intermediate on 'Rootpac-40' and lower on 'Rootpac-20'. Scions grafted on 'Rootpac-20' seemed to be the most dwarf phenotype. Moreover, 'Rootpac-20' performed the lowest values of stem water potential and showed various visual symptoms of chlorosis. Conclusion. Overall, 'Rootpac-40' exhibited a medium capacity to control tree vigor and well adapted to Mediterranean soil conditions.