Document Type : Research paper
Authors
1 Crop and Horticultural Science Research Department, Markazi Agricultural and Natural Resources Research and Education Center (AREEO), Arak, Iran
2 Citrus and Subtropical Fruits Research Center, Horticultural Science Research Institute, Agricultural Research Education and Extension Organization (AREEO), Ramsar, Iran
3 Nuclear Agriculture Research School, Nuclear Science and Technology Research Institute (NSTRI), Karaj, Iran
Abstract
A prevalent problem in pomegranate fruit (Punica granatum L.) is sun damage that decreases the quantity and quality of fruit. The objective of the current research was to evaluate the effects of different photoselective shade net colors and shading percentages on growth traits and pomegranate fruit quality for two years (2019 and 2020). Plots of pomegranate trees (cv. Malase Saveh) were covered to full canopy with two colors of photo-selective shade nets (white and green) and with two shading percentages (30 and 50%), compared to uncovered plots (control). The experiment was carried out in the Saveh region in the same orchard at the time of fruit set (10 June) and the shading treatments were maintained on the trees for four months. The findings showed that shade nets increased relative leaf water content while decreasing temperature and light intensity in the canopy, compared to the control. Pomegranates under nets had a much higher fruit weight and yield than those on uncovered trees. The percentage of sunburn on fruits was dramatically reduced when a shade net was used. In uncovered trees, the percentage of sunburn was 27.85%, whereas in shade treatments, the percentage of sunburn was 0 - 4.5%. The white shade net allowed 50% PAR (Photosynthetically Active Radiation) and caused the highest fruit weight, juice percentage, aril weight and yield, maximum color of fruits and arils, as well as the lowest level of proline content among the shading treatments. The highest values of total anthocyanin (55.13 mg/100 mL), total phenolics (34 mg GAE/100 mL) and vitamin C (21.32 mg/100 mL) were observed after using the white shade net of 50% PAR. As a result, this type of net is recommended for pomegranate orchards because of its efficiency in improving yield and marketable fruits.
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