Interactions

Abstract

Abstract In order to study the time and hormonal factors in source‐sink relations Jonathan blooming was delayed by evaporation cooling, priority of flowering was ensured by removal of terminal shoots at bud‐break, and GA synthesis was influenced by PP 333 (Cultar) spray in the same time. Measurements taken at the end of the cell multiplication phase indicated that cooling reduced, removal of terminal bud and PP 333 spray increased, the sink effect of developing fruits. Removal of terminal bud ceased shoot growth during flowering while on other trees shoots developed. Cooling did not reduce fruit set, no differences were measured in final leaf surface. During intensive fruit growth, sink effects towards P, K, Ca, Mg and B of previously cooled fruits increased while in other treatments they decreased. Storage samples picked 142 days after full bloom (DAFB) contained 27% watercore in the delayed flowering treatment and, during storage, about the same amount of internal breakdown appeared while both disorders were negligible in other treatments. Watercore development corresponded to a 23% loss of Ca incorporated in fruits 135 DAFB.