THE INFLUENCE OF FERTIRRIGATION ON THE DEVELOPMENT OF FRUITS AND THE CONTENTS OF SUGARS AND ORGANIC ACIDS IN ¿REDHAVEN¿ PEACH

Abstract

In 1998 and 1999 during the last thirty days prior to harvest, in intervals of seven days, the influence of fertirrigation on the development of peach cv. ‘Redhaven’ fruits was investigated. We were especially interested in the effects of fertirrigation in comparison with an ordinary method of fertilization and the control (non-fertilized and non-irrigated) on the internal fruit quality. The fruit weight, height, width and thickness were measured. In the same fruits the contents of sugars and organic acids and total soluble solids were evaluated by using HPLC analyses. It was concluded that different fertilization methods and consequently different amounts of added nutrients had significant effects on the contents of malic acid in both years; while in 1999 the effects were observed also on the contents of shikimic acid, total soluble solids, sorbitol, and sucrose. Weekly fruit samplings for the month prior to harvest showed statistical changes in the contents of most sugars (sucrose, glucose, fructose, sorbitol), organic acids (malic, citric, shikimic) and total soluble solids. There were no significant differences in the content of fumaric acid irrespective of fertilization method or time of sampling. As the fruit matures sucrose tends to increase, while glucose and fructose show a decrease in content; there is an increase in the content of total soluble solids. The content of malic acid increased during fruit maturation, while shikimic acid showed a reduction in content. In 1999 the control treatment (non-fertilized, non-irrigated) exhibited higher contents of all organic acids and sugars, as well as sorbitol and total soluble solids.