Influence of controlled water supply on shoot and root development of young peach trees

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Tree Physiology, 15:95–103

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Influence of controlled water supply on shoot and root development of young peach trees

N. A. Hipps (1, 2, 3), L. Pagès (1), J. G. Huguet (1) and V. Serra (1)

1. Station d'Agronomie, Centre de recherches d'Avignon, Domaine Saint-Paul, 84143, Montfavet, France / 2. Horticulture Research International, East Malling, West Malling, Kent ME19 6BJ, U.K. / 3. Author to whom correspondence should be addressed / Received January 24, 1994

Summary

Three controlled water supply treatments were applied to 1-year-old peach trees grown in root observation boxes. The treatments were: I₀, growth medium maintained at 50% field capacity; I₁, water supplied when daily net tree stem diameter change was negative or zero for 1 day; I₃ as for I₁ except that water was applied after net daily stem diameter change was negative or zero for 3 consecutive days.

Trees in treatment I₀ had the greatest mean daily first-order shoot growth rates, and trees in treatment I₃ had the lowest shoot growth rates. Because leaf production rate (apparent plastochron) of first-order shoots was unaffected by treatment, differences in shoot length were due to differences in internode extension and not to the number of internodes. Trees in treatment I₀ had a greater number of second-order shoot axes than trees in treatment I₁ or I₃. Furthermore, an increase in the rate of growth of the first-order shoot axis was associated with an increased tendency for branching (i.e., the development of sylleptic second-order shoots). Increased leaf length was also associated with more frequent watering.

Trees in treatment I₀ had the greatest root lengths and dry weights, and this was attributed to a greater number of first-and second-order (lateral) root axes compared with trees in the I₁ and I₃ treatments. The extension rate and apical diameter of first-order roots were reduced by the I₃ treatment. The density of second-order roots along primary root axes was not affected by any of the treatments.

Keywords: drought, internode extension, irrigation, leaf length, leaf production rate, Prunus persica, root branching, root diameter, root growth rate, shoot branching, shoot growth rate, stem diameter.