Cultivar Selection and Placement of Shadecloth on Midwest High Tunnels Affects Colored Bell Pepper Yield, Fruit Quality, and Plant Growth

Abstract

Additional index words. black shadecloth, Capsicum annuum, leaf area, soluble solids concentration (SSC), SPAD, total titratable acidity (TTA)Abstract. Growing colored bell peppers in high tunnels enhances fruit quality and accelerates ripening. While there are benefits to high tunnel pepper production, increased heat inside the structures can lead to plant stress, blossom drop, sunscald, and reduced marketable yields. The objective of this study was to test shadecloth treatments placed on high tunnels to mitigate heat stress and improve colored bell pepper yield and fruit quality, while also identifying cultivars that perform well within Midwest high tunnel systems. . Six single-poly passively ventilated Quonset high tunnels were used for the experiment. The shade treatments (no shadecloth, 30% light-reducing shadecloth, and 50% light-reducing shadecloth) were applied in June of each season. Within each shade treatment, there were three randomized complete blocks of the seven colored bell pepper cultivars (Archimedes, Delirio, Flavorburst, Red Knight, Sirius, Summer Sweet, and Tequila). Data were collected on yield, fruit quality, and plant growth characteristics. Environmental parameters were monitored throughout the growing season. Both the 30% and 50% shadecloth treatments reduced monthly average and maximum air temperatures within high tunnels, with the largest differences occurring in the months of July and August. The use of a shadecloth reduced the incidence of sunscald by 59% between no shade and 50% shadecloth treatments. While there was no difference between 30% and 50% shade treatments, the use of 50% shadecloth caused a decrease in both marketable number (32%) and weight (29%) of pepper fruit compared with the control. 'Tequila', 'Delirio', and 'Flavorburst' had more marketable fruit per plant. Shade treatments did not affect fruit soluble solids content (SSC), pH, or total titratable acidity (TTA). Shade treatments had no effect on Soil Plant Analysis Development (SPAD) readings, shoot biomass, the number of leaves per plant or the total leaf area per plant; however, plant height increased by an average 14.5 cm for plants under shadecloth treatments. Average leaf size was 11.2 cm 2 larger on plants grown under the 50% shadecloth, compared with the control. Several cultivar differences existed for each fruit quality and plant growth parameter. While differences in fruit quality and plant growth parameters were limited among shade treatments, decreasing marketable yield is concerning. Our research suggests that Midwest growers should not exceed 30% light-reducing shadecloth on their high tunnels for colored bell pepper production.

Exogenous arginine modulates leaf antioxidant enzymes and hydrogen peroxide content in tomato plants under transient heat stresses

“…However, some abiotic factors are still hard to manage even in protected environments during the summer. For instance, heat stress can be detected in plants from regions with hot seasons (Lang et al 2020), despite the use of ventilators and water sprays (Ferrari and Leal 2015).…”

“…High temperature inhibits photosynthetic activity, alters cellular homeostasis, impairs growth of vegetative and reproductive organs and accelerates plant physiological maturity, frequently triggering reductions in the crop productivity while increasing fruit disorders and visual damages (Lang et al 2020;Nagarajan and Nagarajan 2010;Singh et al 2017;Wang et al 2018). Most of such side effects are resulted from oxidative stress, which arises from a disproportion between production and elimination of reactive oxygen species (ROS) that can trigger protein oxidation, cytotoxicity and even DNA abandonment, hence threating the cellular viability (Soares et al 2019).…”

Seasonal Difference of Fruit Quality Attributes and Physiological Disorders in Paprika Cultivars under a Simulated Export System

“…That is, the SSC levels in the conical type of paprika cultivar did not respond differently to the export season. Regardless of the export season, both the SSC and TA levels were greatly affected depending on the cultivar type at harvest (Lang et al, 2020). During cold storage, the SSC level of all cultivars was not strongly affected (Lim et al, 2008b).…”

Spectral Blocking of Solar Radiation in High Tunnels by Poly Covers: Its Impact on Nutritional Quality Regarding Essential Nutrients and Health-Promoting Phytochemicals in Lettuce and Tomato

“…Luminescence poly can prevent direct sunlight and avoid high temperatures in the tunnel, thus reducing plant stress and improving plant growth. Shade cloths are also often used to reduce the temperature and alter the microclimate within the tunnel and thus, the plant growth and other plant responses [21]. Additionally, there have been studies aimed at determining plant performance by altering solar radiation with various films [19,22].…”