Miniature Head Lettuce Yield and Anthocyanin Concentration under High Tunnels and the Field in Georgia

Abstract

This study evaluated the yield of eight miniature lettuce (Lactuca sativa) cultivars (i.e., mini-lettuce) grown under organically managed high tunnels compared with a field system during two spring seasons in Georgia. Mini-lettuce required an average of 36 to 40 days to harvest in both systems with a 86% to 97% marketability rate. The high tunnels provided a heat gain on the coldest days, decreased leaf wetness, and resulted in a lower daily light integral compared with the field. In 2015, mini-lettuce yields were similar between the high tunnel and field, but in 2016, yields were greater under the high tunnels. In 2016 only, there was a significant system by cultivar interaction for yield, suggesting that the high tunnels provided a yield increase for ‘Baby Green Oakleaf’ and ‘Spretnak’ mini-lettuce. Differences in the daily light integral between the high tunnels and field appeared to affect the accumulation of anthocyanins in red-pigmented mini-lettuce. Anthocyanin concentrations were 26% to 194% greater in mini-lettuce grown in the field compared with under high tunnels. The cultivar Rhazes had the greatest anthocyanin concentrations of all red-pigmented mini-lettuce evaluated but also lower yields.

Nutritional Characterization Based on Vegetation Indices to Detect Anthocyanins, Carotenoids, and Chlorophylls in Mini-Lettuce

“…Several studies have demonstrated the influences of environmental conditions, such as temperature, fertility, soil moisture, and mainly light, in addition to genetic factors, on the accumulation of phytopigments [75][76][77][78][79]. Thus, a lettuce cultivar may show different concentrations of these compounds depending on the environment in which it is grown.…”