Efficace l’impiego di silicato di sodio e cloruro di calcio per ridurre lo spacco dei frutti

Fruit cracking caused by rainfall prior to harvest is a major problem in sweet cherry production, reducing drammatically the fruit marketability. Currently, spray applications with calcium salt solutions (mainly calcium chloride) represent the most widespread means used by growers to prevent fruit cracking in cherry orchards not covered by a removable and impermeable plastic flat roof. In order to evaluate the effectiveness of silicon in the prevention of fruit cracking, three field trials were conducted in Italy (2002 and 2007) and the United States (2003). The experiments were carried out on mature trees of the cvs. Van, New Star and Emperor Francis, comparing the following treatments: water (control), calcium chloride and sodium silicate. Multiple sprays (3) were applied weekly from fruit veraison to approximately one week prior to harvest. The resulting data show that under conditions conducive to cracking, sodium silicate reduced the percentage of cracked fruits to a similar or larger extent than calcium chloride. The effectiveness of silicon foliar application in the prevention of sweet cherries cracking may be due by both the enhancement of fruit cell wall elasticity and the reinforcement of its structure. Besides, ydrophobic silica (SiO2) deposits on fruit surface, may have reduced water absorption into the fruit during rainfall.