ELSEVIER Scientia Horticulturae 66 ( 1996) 18 zyxwvutsrqponmlkjihgfedcbaZYXWVU 1- 189 zyxwvutsrqponmlkjihgfedcbaZYXWVUTS SCIENTIA HORTICULTURR Changes in calcium contents during melon ( Cucumis melo L.) fruit development A. Bernadac *, I. Jean-Baptiste, G. Bertoni, P. Morard zyxwvutsrqponmlk Laboratoire de Physiologie V$&ale, Ecole Nationale Sup&ieure Agronomique, 145 avenue de Muret, F-31076 Toulouse Ckdex. France Accepted 15 April 19% zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQ Abstract Melon (Cucumis melo L. var. Maestro) plants were grown in soilless culture under plastic tunnels. A 17-day calcium deficiency was applied to plants bearing fruits of various ages (between 3 and 20 days after anthesis) and the fruits were harvested between 20 and 37 days after anthesis. The calcium concentrations in the fruits of the control plants decreased between 20 and 37 days after anthesis (ripe fruit): the decrease in calcium concentration was steady in the flesh whereas it occurred only in the last few days in the rind. Calcium accumulation within the fruit occurred quite early: 80% of calcium present in ripe fruit was already there 20 days after anthesis. Thus, a calcium deficiency applied to 20-day-old fruits had no significant effect on the calcium content at the time of harvest. In contrast, younger fruits were very susceptible to calcium deficiency and displayed a significant decrease in calcium content. Keywords: Cucumis melo; Melon; Calcium nutrition; Fruit development 1. Introduction The calcium contents of most fruits (Marschner, 1974) are generally much lower (below 1 mg g- zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA ’ DM) than those of leaves (45 mg g- ’ DM). However, calcium is an essential element involved in cell division, elongation and fruit growth (Burstrijm, 19681, in addition to having a positive effect on fruit quality criteria such as storage ability, vitamin C content and firmness (Bangerth, 1979). Disturbances in calcium nutrition result in the appearance of characteristic symptoms in fruits of various species: bitter pit in apple, blossom-end rot in tomato or tip bum in strawberry (Shear, 1975). * Corresponding author: Tel. 33-62- 13-65-6 1; Fax 33-61-42-30-29; Email bemadac@ensat.fr. 0304-4238/%/$15.00 Copyright 0 1996 Elsevier Science B.V. All rights reserved. PII SO304-4238(96)00918- 1