Tree vigor, fruit yield and quality of nectarine trees grown under red photoselective anti-hail nets in Southern Italy

In Italy, hailstorms represent a major threat for fruit tree cultivation. Therefore many peach growers have protected their orchards with anti-hail nets. Many studies have demonstrated that photoselective shade nets can induce interesting photomorphogenic effects on several cultivated species. The aim of the present research was to study the effect of red photoselective anti-hail nets on nectarine tree vigor, fruit yield, and fruit quality. The study was carried out in a private orchard located in Eboli (Southern Italy) on mature nectarine trees 'Laura' grafted on GF677. On February 2008, five rows of trees were covered with a red photoselective anti-hail net (30% shade factor), whereas another five rows were covered with a white, transparent anti-hail net (10% shade factor) that is the most common type of anti-hail net used in the area. During the experiment a number of parameters related to tree vigor, fruit yield and quality were measured. Trees under the red net had higher light interception than trees under the white net and this suggests that the red net induced an increase in tree vigor, as previously reported for other species. Net color did not significantly affect the number of fruit per tree and fruit yield. Similarly, there were no significant differences in fruit size distribution or fresh fruit weight between trees under the two types of nets. Both cover and ground color of fruit skin was slightly, but significantly, less under red nets. On the other hand, fruit of trees under the red net tended to have significantly higher flesh firmness, lower soluble solids content and lower percent dry matter than fruit of trees under the white net. These effects may be related to a slight delay in fruit maturation induced by the red net or to a negative effect of this net on sugar accumulation in the fruit (potentially because of the higher shade factor of the red net compared to the white net)