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How to prevent the appearance of 'creasing' in Navel oranges

The application of the Harpin αβ protein, marketed as ProAct®, prevents the appearance of creasing in Navel oranges. That is the conclusion of a study recently published by the Institute for Agricultural Research in Valencia (IVIA) after four years of testing in trees while the production was in full swing.

The results of the study are clear: ProAct® is able to alleviate the impact of creasing in orange plantations by increasing the total and bound calcium content of the fruit's peel. In order to reach this conclusion, experiments have been carried out from 2014 to 2018. In the first three years, the study focused on early varieties of Navelina oranges and in the fourth year on the late Lane Late variety.

Left: Orange with creasing. Right: Orange without creasing.

Season after season, creasing has been one of the biggest problems for orange growers. This physiological condition affects the fruit's skin, and consequently, the oranges affected by it cannot be marketed as fresh fruit. As a result, the majority is discarded or used for the production of juices, thereby bringing prices down.

The results of the tests point to the successful finding of a solution to this problem. The Harpin αβ protein, a substance that plays a key role in the physiological processes of plants, limits the damage to crops that are affected by adverse weather conditions (drought or high temperatures) or by nutrient deficiencies, such as a lack of calcium, which cause creasing. Moreover, the application of this protein improves the quality of the oranges, increasing the fruit's resistance during its handling and marketing.

Results of the application of ProAct® on Navelina and Lane Late varieties

Figure 1: Percentage of fruit affected by creasing on two independent plantations of Navelina oranges in two years. Three applications corresponding to the phenological phases: falling petals, fruit setting and color change. Treatments: A = water; C = conventional (giberellin and calcium nitrate); P = ProAct®; M = mixture of ProAct® and conventional (*p-value <0.1; **p-value <0.05, t-student. Comparison with the corresponding control plant for each year, AAA). Source: Levante Agrícola.

During the first two years of the application of ProAct®, there was a drop in the average share of fruit affected by creasing during the fall of the petals, the fruit setting and the color change. During its application to the late variety Lane Late, however, there was an increase in the amount of bound calcium in the fruit's peel, as well as an improvement in the firmness of the ripe fruit. For both varieties, the results entail an improvement in quality, better access to export markets and greater profitability for the grower.

This research is the result of the collaboration between the IVIA and Plant Health Care, a leading supplier of patented and scientifically tested organic products for agriculture, including the biostimulant ProAct®. ProAct® is certified for fruit and vegetable cultivation by Zerya Producción Sin Residuos SL, and has been nominated as the best biostimulant for the Agrow Awards, which will be presented in London on November 12th.


For more information:

Ángel Marín
Plant Health Care
C/Castelló, 82
28001 Madrid, Spain

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