Impact of Shade and Fogging on High Tunnel Production and Mineral Content of Organically Grown Lettuce, Basil, and Arugula in Georgia

Abstract

This study evaluated the impact of shade cloth and fogging systems on the microclimate at the plant canopy level and yield of basil (Oscimum basilicum L.), arugula (Eruca vesicaria subsp. Sativa L.), and lettuce (Lactuca sativa L.) planted in mid-September and early October in high tunnels. Fogging systems were installed at canopy level in plots within shaded (30%) and non-shaded high tunnels. Average air temperatures in the shaded high tunnels were 0.9 °C lower than non-shaded high tunnels during the day. Shade cloth significantly reduced soil temperatures during the day and night periods by 1.5 °C and 1.3 °C, respectively, compared to non-shaded treatments. Fogging systems did not have an impact on air temperature, soil temperature, or relative humidity, but did increase canopy leaf wetness. Shade and fogging did not impact the yield of any of the crops grown. Yield was impacted by planting date, with earlier planting result in higher yields of lettuce and basil. Yields for arugula were greater during the second planting date than the first. Planting date and shade cloth interacted to affect the concentrations of macronutrients.

Influence of Soil and Nutrient Management Practices on Crop Productivity and Quality in High Tunnel Organic Leafy Green Production

“…Mineral nutrients are important vegetable quality parameters that can be affected by fertilization programs and environmental conditions (Laur et al 2021;Zhao et al 2007). The average macronutrient and micronutrient levels of pac choi found in the current study were adequate to high, suggesting nutrients were not a limiting factor for growth (Johnson et al 2012;Zhao et al 2007).…”

“…Similarly, Woldetsadik et al (2018) observed positive correlations between lettuce yield and certain nutrients, such as P, K, and Mg, when grown with biochar application in a pot experiment. However, according to Laur et al (2021), while arugula (Eruca sativa) yield was linked to higher levels of P, S, and Cu, a similar correlation was not found in lettuce or basil (Ocimum basilicum) grown in high tunnels. Further investigation is warranted to explore the impact of mineral nutrient uptake on the yield of different leafy greens grown in various production systems.…”

Comparison of Different Temperature Control Systems in Tropical-Adapted Greenhouses for Green Romaine Lettuce Production

“…Recently, various cooling techniques and systems, including fan pad evaporative cooling, shade, misting or fogging, natural ventilation (through structure or employing exhaust fan), or combination systems, have become available for plant production in greenhouses [5]. Many studies have evaluated the appropriate systems for controlling microclimate in the greenhouse, especially the effect of fogging, shading, and ventilation fans on greenhouse performance for vegetable production in hot climates [6,[38][39][40][41][42]. Several studies investigated whether mist/fogging systems could lower interior air temperature more than open field production [38] or under the greenhouse using only natural ventilation via roof opening [39][40][41] during summer periods.…”

Using High Tunnels to Enhance Organic Vegetable Production in Florida: an Overview

“…While elevated fogging systems are widely and successfully used to cool air temperatures in commercial greenhouse structures (Figure 9), research conducted in Georgia showed that they were only marginally effective in high tunnels. The lower rate of air movement in the passively ventilated structure hindered elevated fogging systems (Laur et al 2021a). If growers wish to use a fogging system, they should consider adding horizontal airflow fans to their structure, which help improve air movement and evaporation.…”

“…Growers often encounter issues with starting cool-season crops in the late summer and fall in tunnels. Research in Georgia and Kansas has shown the effectiveness of using shade cloth to grow cool season crops out of season (Laur et al 2021b;Zhao and Carey 2009) (Figure 12). Late summer in South Georgia, shade nets that covered the high tunnel improved tomato plant growth (Bag et al 2021).…”