Effects of foliar calcium applications on quality and shelf life of strawberry, raspberry, blackberry, and blueberry fruit

Abstract

The following work concerns the effect of foliar application of calcium formulations, i.e. Ca oxide (5 ml/l), Ca-silicate (0,4 ml/l); and nano-Ca (3 ml/l) on quality of strawberry (cv. Lussa),  raspberry (cv. Maravilla), blueberry (cv. Ciello)  and blackberry  (cv. Elvera). The experimentation was conducted in a commercial farm specialist in berries production under plastic covers, located in Kenitra region. Treatment applications, on fruit and leaves, were started April 16 and repeated each ten days, i.e. April 26 and May 6^th, 2018, while harvest was accomplished seven days after each treatment application, i.e. April 23, May 3 and 13, 2018. The results obtained for strawberry showed that calcium treatment significantly enhanced fruit firmness; the rate of increase was proportional to the number of applications while the maximum increase was obtained for nano-Ca treatment. A significant decrease in fruit soluble solids contents, ranging from 1,23 to 2,01 °Brix relatively to the control, was observed following Ca treatments. For raspberry, Ca treatments significantly increased fruit firmness, the rate of increase was proportional to the number of applications while the maximum firmness was obtained by Ca silicate treatment for the three harvest dates. Soluble solids content was significantly decreased for fruit of the second harvest date. Treatments of blueberry resulted in an increase of fruit weight, significant for the first and third harvest, relatively to the control. Fruit firmness was improved significantly following all Ca treatments, relatively to the control. Fruit soluble solids content was significantly decreased for treated fruit, relatively to the control, harvested the third date. Blackberry Ca treatments significantly increased fruit weight, the increase per berry, relatively to untreated fruit, ranges   from 1,00 to 1,28 g for the first harvest, 0,92 to 1,35 g for the second harvest, and  2,07 à 2,55 g for the third harvest. Fruits of the latest had also a significant increase in firmness.   All Ca treatments improved postharvest quality retention and reduced fruit weight loss for all berry species after one week storage at temperature of 2 to 4 °C.

Keywords: strawberry, raspberry, blueberry, blackberry, quality, calcium.