Bell Pepper (Capsicum annum L.) under Colored Shade Nets: Plant Growth and Physiological Responses

Abstract

<jats:p>Use of colored shade nets has shown benefits in bell pepper and other horticultural crops. There is still, however, limited information on plant growth and physiology of bell pepper crop grown under colored shade nets. The objective was to determine the effects of colored shade nets on plant growth, leaf gas exchange, and leaf pigments of field-grown bell pepper. Experimental design was a randomized complete block with four replications and five shade treatments (black, red, silver, and white nets, and an uncovered control). Mean and maximal air temperature and midday root zone temperature (RZT) were highest in the unshaded treatment. Differences in air temperatures between shade net treatments were smaller compared with the differences in RZT between treatments. Plant fresh weight and stem diameter were reduced in the unshaded treatment, and there were no plant fresh weight and stem diameter differences among shade nets. The incidence of Phytophthora blight (caused by <jats:italic>Phytophthora capsici</jats:italic>) was greatest in the unshaded treatment. Leaf stomatal conductance (<jats:italic>g</jats:italic><jats:sub>S</jats:sub>) and photosystem II efficiency were reduced and leaf temperature increased in unshaded conditions. Leaf net photosynthesis, <jats:italic>g</jats:italic><jats:sub>S</jats:sub>, internal CO<jats:sub>2</jats:sub>, and PSII efficiency decreased with increasing leaf temperature. Differences in leaf temperature among shade net treatments were because of differences in solar radiation captured by leaves. Leaf total carotenoids were lowest in unshaded conditions and there were no differences in total carotenoids among the shade nets. Chlorophyll <jats:italic>a</jats:italic> concentration and chlorophyll <jats:italic>a</jats:italic>/<jats:italic>b</jats:italic> ratio was lowest in unshaded conditions. Leaf total phenols, flavonoids, and cupric reducing antioxidant capacity (CUPRAC) values were highest in red net and in unshaded conditions. Trolox equivalent antioxidant capacity (TEAC) values were highest in red net and lowest in silver net. In conclusion, compared with unshaded conditions, shade nets resulted in improved bell pepper plant growth and leaf gas exchange. These responses were due primarily to the reduced leaf and root zone temperatures under shaded conditions, regardless of the color of shade net. The differences in plant growth and function due to color of shade net were inconsistent or minor for most of the plant variables measured.</jats:p>

Color Shade Nets Affect Plant Growth and Seasonal Leaf Quality of Camellia sinensis Grown in Mississippi, the United States

“…Shading affects radiant exposure, temperature, humidity, soil conditions, and microorganism biodiversity and can protect plants from sunburn, frost, and hail (3)(4)(5)(6)(7)(8). Shading was reported to improve the yield and quality of a number of horticultural crops, including fruits, vegetables, ornamentals, herbs, and tea (9)(10)(11)(12)(13)(14)(15). The application of shade on horticultural crops is becoming more popular in the recent years (16).…”

Fluid Dynamics Simulation and Temperature Gradient Validation along a Greenhouse Temperature Gradient

“…The e ciency of photosynthetic system improved under warm temperature. However, WUE in cool season crops is normally strengthen by optimal temperatures [27,29,30]. Regarding the A-Ci and light curves (Fig.…”

Fluid Dynamics Simulation and Temperature Gradient Validation along a Greenhouse Temperature Gradient

“…It was followed by the Kimchi cabbage grown in zone A. The area with the lowest maximum photosynthetic rate was zone C. Previous research revealed that the maximum carboxylation rate, maximum rate of electron transport, and triose phosphate utilization rate of the higher temperature treatment plants were significantly lower than those of the control [7,8,22,26,29,31,32].…”

“…. Especially, using the extreme weather simulators [26] have documented the impact of moderate and extreme climate change scenarios on growth, morphological features, photosynthesis, and fruit production of hot pepper. Similar work has dealt with the temperature gradient and air-soil as a factor in the optimization of net photosynthesis in whole plants [27].…”