ROOT DEVELOPMENT OF ALMOND ROOTSTOCKS IN A YOUNG ALMOND ORCHARD UNDER TRICKLE IRRIGATION AS AFFECTED BY ALMOND SCION CULTIVAR

Minirhizotrons were used to study the development of the root system (down to 100 cm) of almond trees cvs Atocha and Ramillete on 'Pestaneta' almond rootstock. The study was carried out during the first years of development of the trees under trickle irrigation. In 'Atocha' trees, with an upright growth habit, root development was greatest at a depth of between 60 and 100 cm; in 'Ramillete' trees, with a rather spreading growth habit, root development was greatest in the surface layers of the soil. However, in both graft combinations, most roots developed in the first 60 cm of depth. The root system dynamics in the whole soil profile throughout the annual cycle showed increases and decreases in root growth during the same periods for both scion/rootstock combinations; in both cases a decline in the root growth occurs coincided with the period when vegetative growth and rapid fruit development overlap.