Shade Effect on Growth and Productivity of Tomato and Chili Pepper

Southern U.S. states such as Texas experience high temperatures and intense solar radiation during the summer production season. Use of shadecloth is common in Spain and other Mediterranean countries and is becoming popular with homeowners or small-acreage farmers in Texas. Little information is available on the applicability of using shadecloth on tomato (Solanum lycopersicum) and chili pepper (Capsicum annuum) in the warm climate of Texas. The effects of two shade nets differing in shading intensity on growth, chlorophyll fluorescence, and photosynthesis of ‘Celebrity’ tomato and ‘Sweet Banana’ chili pepper was investigated from May to Aug. 2014. Plants were grown in 50% shade, 70% shade, or full sun. Compared with the unshaded control, tomato grown in 50% shade had similar yield and shoot fresh and dry weight and less photochemical stress. The 50% shade reduced number and weight of unmarketable tomato fruit. Similar results were obtained with chili pepper except for lower numbers of marketable fruit. The 70% shade significantly reduced yield parameters of both tomato and chili pepper. Both 50% and 70% shadecloth reduced leaf temperatures of tomato and chili pepper with variable results in June and July. Growth index [(height + width 1 + width 2) ÷ 3] of tomato and chili pepper was the highest with 50% shade, the lowest with full sun, and intermediate with 70% shade. The maximum net photosynthetic rates (Pn) of tomato determined from a Pn to light response curve supported the results on growth and yield. However, the maximum Pn of chili pepper was higher in full sun treatment compared with 50% or 70% shade. The latter two were almost identical. This one growing season study indicated that shading at 50% benefits tomato and chili pepper production in west Texas by reducing heat stress; however, a shading percentage below 50% may be better