© 1997 Heron Publishing—Victoria, Canada
Crop load and water stress effects on daily stem growth in peach (Prunus persica)
M. E. Berman and T. M. DeJong
Department of Pomology, University of California-Davis, Davis, CA 95616, USA / Received June 12, 1996
Summary
We investigated crop load and water stress effects on diurnal stem extension growth of field-grown peach (Prunus persica (L.) Batsch) trees. Neither the presence of fruit nor reduced irrigation significantly altered the timing of diurnal fluctuations
in stem growth rate. Stems with subtending fruit had significantly reduced growth compared to stems with no subtending fruit.
Crop load had no significant effect on relative stem extension rates and the majority of the reduction in absolute growth
was the result of a smaller zone of elongation in fruit-bearing stems than in stems with no subtending fruit. Fruit removal
did not increase growth rates within 24 h. When irrigation was reduced, the length of the stem elongation zone and total daily
stem growth were significantly decreased relative to well-irrigated controls and the decreases were highly correlated with
stem water potential. Compared with well-irrigated controls, relative stem extension rates of water-stressed trees were reduced
at several times during the 24-h period, but the degree of reduction was not proportional to the difference in stem water
potentials between the treatments.
Keywords:
diurnal growth patterns, growth zone, stem elongation, water potential.
