Document Type : Research paper
Authors
1
Horticultural Sciences Research Institute, Shahid Fahmideh St. Karaj, Iran
2
Agricultural Research, Education and Extension Organization
Abstract
Climatic changes, heat stress, and reduction of water resources are essential challenges of recent years. The present study was carried out to determine the effect of shade net on physiological, and microclimatic parameters and the quantitative and qualitative yield of four grapevine cultivars. For this purpose, Sahebi, Red Sultana, Red Asgari, and Mish Pestan cultivars were evaluated in terms of quantitative and qualitative traits, chlorophyll fluorescence, and microclimate under and outside of green shading net with a porosity at 50%. The shading net decreased the temperature by 3.2ºC and increased the humidity by 5.31%. In terms of chlorophyll stress, the shading net caused a significant increase in maximum fluorescence and variable fluorescence by 48% and 46.2%, respectively, but had no significant effect on primary fluorescence and yield potential quantum. The shading net significantly decreased by 15.9%, 17.6%, 15.2%, and 6.5% of external canopy temperature, leaf temperature, and internal canopy temperature and CO2, respectively, and increased by 64.3% of canopy humidity. Internodal length increased significantly by 66.2% under the shading net. The use of shading net significantly increased vine yields by up to 65%. The interaction effect of cultivar in the shading net was also significant only in humidity and temperature of the inside canopy, and total soluble solids. The results showed a reduction in heat stress, improvement in fruit quality, and late ripening in using the shading net. Therefore, for table grape production, it is recommended to collect the shading net at the veraison time to prevent late ripening.
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