IMPROVEMENT OF VITAMIN C, PHENOLICS AND COLOURATION IN APPLE FRUIT WITH ORGANIC MULCH USED AS A REFLECTIVE MATERIAL

Abstract

The objective of this study was to examine organic mulch (pine sawdust) as an alternative for conventional herbicides in fruit orchards in order to improve fruit quality. Light (PAR) reflection from the sawdust mulch was up to 2.5-fold increased. The peel of fruits from apple trees with mulched row stripes contained more phosphorus, magnesium and calcium (of importance for storability and shelf-life), as well as 16-250% higher phenolic content, including catechin and flavonols, compared to the herbicide treatment. Fruit from cultivars ‘Krasivoye’ and ‘Gigulevskoye’ with medium vitamin C content (usually around ca. 30 mg/100 g FM peel), was increased by organic mulches by 22 and 63%, respectively, but not in the cultivar ‘Bogatir’ with a large inherent vitamin C content, usually around 50 mg/ 100 g FM fruit peel. Thus, organic mulching enhanced the anti-oxidant content correlated with red colouration of the fruit skin in all cultivars examined, as a consequence of increased light (PAR) reflection from the mulch.