Daily shoot extension growth of peach trees growing on rootstocks that reduce scion growth is related to daily dynamics of stem water potential

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Tree Physiology, 23:695–704

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Daily shoot extension growth of peach trees growing on rootstocks that reduce scion growth is related to daily dynamics of stem water potential

Boris Basile (1), Jordi Marsal (2) and Theodore M. DeJong (3, 4)

1. Dipartimento di Arboricoltura, Botanica e Patologia Vegetale, Università degli Studi di Napoli Federico II, 80055 Portici, Napoli, Italy / 2. Institut de Recerca i Tecnologia Àgroalimentàries (IRTA), Area de Tecnologia Frutícola, Centre Udl-IRTA, 25198 Lleida, Spain / 3. Department of Pomology, University of California, Davis, CA 95616, USA / 4. Author to whom correspondence should be addressed (tmdejong@ucdavis.edu) / Received April 2, 2002; accepted December 30, 2002; published online June 2, 2003

Summary

We studied relationships between diurnal patterns of stem water potential (Ψ_STEM) and stem extension growth of the same scion cultivar growing on three rootstocks with differing size-controlling potentials. The peach trees (Prunus persica (L.) Batsch) used in this field experiment consisted of an early-maturing freestone cultivar, ‘Flavorcrest,’ grafted onto three different rootstocks: Nemaguard (a vigorous seed-propagated control, P. persica × P. davidiana hybrid), Hiawatha (an intermediate vigor rootstock, derived from an open pollinated seedling of a P. besseyi × P. salicina hybrid) and K-146-43 (a semi-dwarfing rootstock, P. salicina × P. persica hybrid). Diurnal patterns of Ψ_STEM and stem extension growth were measured on six dates (March 29, April 12, April 26, May 10, May 24 and June 18) during the primary period of peach shoot extension growth. Rootstocks clearly affected diurnal patterns of Ψ_STEM and stem extension growth. Trees on K-146-43 had the lowest midday Ψ_STEM and stem extension growth. Differences among rootstocks in the amount of diurnal oscillation in Ψ_STEM explained stem extension rate differences induced by the three rootstocks. The sensitivity of shoot extension growth to tree water relations tended to decrease as the season progressed and was not apparent by mid-June. The results of the study indicate that water relations may play an important role in the dwarfing mechanism induced by size-controlling peach rootstocks.

Keywords: diurnal pattern of stem extension growth, diurnal pattern of stem water potential, dwarfing mechanism, dwarfing rootstocks, Prunus persica, water relations.