Effects of Shade Cloth on Specialty Crop Production in High Tunnels

Southern high tunnels can have very high heat and light loads relatively early in the spring. This study was conducted to investigate the potential of using shade cloths of different colors to modify the microenvironment within high tunnels and to evaluate their impact on crop yield and quality. Seven different types of shade clothes were tested, including Aluminet, ChromatiNet Red, ChromatiNet Grey, ChromatiNet Blue, ChromatiNet Pearl/White, Black, and White. All the shade clothes were rated to provide 50% shade. One treatment without shade cloth was also included as a control. Zinnia Benary’s Giant Mix and two cultivars of lettuce (Two Star and New Red Fire) were transplanted into three high tunnels on two transplanting dates in spring 2013. We measured how the treatments influenced air, soil, and leaf temperatures; plant growth index; number of cut flowers and cut stem length; and yield and quality of lettuce. Both presence and type of shade were influential. Soil, air, and leaf temperatures were all influenced by shade cover, and were consistently lower under shade than in the unshaded controls. We also observed differences in plant growth, lettuce yield, cut flower stem numbers and stem length, red lettuce coloration, lettuce bolting, lettuce days to maturity and even lettuce taste under different color shade.