Radiation, yield, and fruit quality of 'Gala' apples grown under white hail protection nets
2012
Amarante, C.V.T. | Steffens, C.A. | Argenta, L.C.
Damages caused by hail storms on apple trees can be avoided by covering them with nets. However, the net will change the amount and quality of the light supplied to the trees and, therefore, it can affect yield and fruit quality. This research was carried out to assess these aspects on 12-15-year-old apples trees of 'Gala'/MM111 rootstock. The work was conducted over three growing seasons (2003-2004 to 2005-2006) in a low density orchard (at a spacing of 5.5×3.0 m), in São Joaquim, State of Santa Catarina, southern Brazil. The experiment followed a completely randomized block design, with two treatments (uncovered/control plants, and plants covered with white nets) and five replications (with the plant corresponding to the experimental unit). The net reduced by 19% the photosynthetically active radiation measured between 8:00 h and 15:00 h at the top of the tree canopy. The red:far red ratio of the light inside the tree canopy was not affected by the covering net. The shade provided by the white net increased the total chlorophyll content (mg/m2) and the specific area (cm2/g dry weight) of the leaves. Fruit yield was not affected by the net. For fruits harvested at the commercial period, the net reduced fruit density, flesh firmness, and soluble solids content, increased the starch index, and had no effect on titratable acidity, skin color (background color and blush area), severity of russeting, and number of seeds per fruit. Fruit grown under the covering net developed less sunburn, fruit fly injury and bitter pit. The results indicate that the hail protection net does not negatively affect fruit quality and yield of 'Gala', but it can enhance fruit maturity on the tree.
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