Light level under shading nets affects bell pepper (Capsicum annuum L.) fruit mineral nutrients

Bell pepper (sweet pepper) is an important crop in the southeast US. High temperature conditions may affect flowering, fruit set and fruit yields and may result in increased incidences of fruit physiological disorders such as blossom-end rot and sunscald. Shading nets have been found to increase fruit yields, reduce water requirements, and increase the irrigation water use efficiency in bell pepper. There is, however, little information on the impact of shading on fruit quality and mineral nutrient composition. The objective of this study was to determine the effects of shade level on the concentration of mineral nutrients in bell pepper fruit. Study was conducted at the Horticulture Farm, University of Georgia, Tifton, GA, during the spring-summer of 2009 and 2010. Soil was a sandy loam with a pH of 6.5. The experimental design was a randomized complete block with four replications and 20 treatments (5 shade×4 cultivar combinations). Shading treatments were: 0, 30, 47, 63, and 80%. Cultivars were 'Camelot' (Seminis, Oxnard, CA), 'Lafayette' (Siegers Seed Co., Holland MI), 'Sirius' (Siegers Seed Co., Holland MI), and 'Stiletto' (Rogers, Boise, ID). Results showed that fruit concentrations of N, P, K, increased and while the concentrations of Al, B, Mn, Mo, Na and Ni decreased with increased shading levels. Concentrations of Ca, Mg, S, Cu, Fe, and Zn showed no little response to shade level. Shading possibly produced amelioration of heat stress that might have resulted in increased mineral nutrient uptake. It may be that heat stress amelioration by shading benefited bell pepper plant growth indirectly by modifying the crop thermal environment to be more favorable for mineral nutrient uptake.