Effect of water stress applied during the final stage of rapid growth on peach trees (cv. Big-Top)

Because of the importance of water restrictions to peach quality during the final stage of rapid fruit growth, the incidence of different intensities of water stress during this critical period were investigated from 1994 to 1999. The experiment was carried out in pot trials so as to control the wat er supply to the peach trees. Three water treatments were applied, accordin g to stem diameter changes [J. Hortic. Sci. 67 (4) (1992) 602]: T1-optimum irrigation; T2-light water stress; T3-severe water stress. The results are only presented for the last 2 years of the experiment: 1998 and 1999. Veget ative growth and flower bud numbers did not differ between the three treatm ents. However, stem diameter changes, stem water potential and leaf photosy nthesis were well differentiated by the three treatments. In particular, le af photosynthesis was reduced under T2 and even more so under T3 when solar radiation increased above 1000 mu mol photons/m(2)/s. The highest yields a nd fruit weights were achieved under both T1 and T2, and the lowest average soluble solids' percentages under T2 and T3. However, when considering fru its of the same grade, soluble solids' percentages tended to be higher unde r T3 than under T2 and, in 1998, under T1. When light water stress was appl ied, soluble solids' percentages appeared to slightly decrease while peach weights remained relatively constant. On the other hand, when major limitat ions in water and carbohydrate supplies arose as a result of severe water s tress, average fruit weight strongly decreased and soluble solids' percenta ges increased, when comparing fruits of the same grade. Thus, peach taste q uality could be considered as being improved by severe water stress. (C) 20 01 Elsevier Science B.V. All rights reserved.