Influence of calcium nutrition on water soaking disorder during ripening of Cantaloupe melon

Cantaloupe melon (cv. Talma) is very sensitive to water soaking, a disorder characterized by a glassy texture of the flesh, which considerably decreases the commercial quality. The influence of calcium levels in the fertigation solution and ethylene production of fruit on the vine, as well as its effect on peel and pulp color, calcium concentration in the fruit, and development of water soaking during ripening was studied. Cultivation was on perlite and rockwool substrates. The calcium level (1.3 or 4.0 mmol l(-1)) in the nutrient solution did not affect the time course of ethylene emission, but high calcium concentration increased the ethylene maximum, from 45 to 78 ppm in perlite and 25-38 ppm in rockwool. The effect of calcium on the development of water soaking in pulp was clear with close to 98% of fruits affected by this disorder, in the calcium-deficient treatment, while only 16.5 and 28.7% of the fruit treated with calcium (4.0 mmol l(-1)) and grown in perlite and rockwool, respectively, were affected. Peel color (b*) was not affected by substrates or calcium nutrition. The colorimetric values showed a delay of the ripening date when cultivated with a deficient calcium solution. With both substrates, a* in the flesh was lower in calcium-deficient fruits due to deterioration of tissues caused by vitrescence or water soaking. Results show that low calcium levels induced the appearance of water soaking and affect ethylene synthesis. Color determination is not an adequate method for detecting affected fruits. (C) 2004 Elsevier B.V. All rights reserved.