Shading Nets Research Articles

Response of Ethiopian Mustard (Brassica carinata A. Braun) to Different Levels of Vermicompost in North East, Botswana

A pot experiment was carried out in a net shade in Impala Research Station, North East District of Botswana, to investigate the response of Ethiopian mustard (Brassica carinata A. Braun) to different levels of vermicompost. The experiment treatments comprised of pure soil (Treatment 1 (T1)) and homogeneous mixture of vermicompost and sandy loam soil (T2 = 25% VC, T3 = 50% VC, T4 = 75% VC and T5 = 100% VC). In each pot, two plants were raised and the data of parameter measured were collected from them. The results showed that increasing the dosage of vermicompost, significantly increased number of leaves, plant height, leaf length, leaf width, leaf area and leaf weight. The performance of Ethiopian mustard did not differ significantly at a range between 50% VC and 100% VC in all measured parameters. Leaf length, leaf width and leaf area reached higher values at 75% VC. This suggest that level 75% VC can be used in a potting medium when growing Ethiopian mustard as a leafy vegetable.

Yellow light promotes the growth and accumulation of bioactive flavonoids in Epimedium pseudowushanense

The plant species of the genus Epimedium L. are well-known traditional Chinese medicinal herbs with special therapeutic effects on human beings and animals in invigorating sexuality and strengthening muscles and bones. In large-scale cultivating Epimedium that is a typical shade plant species, they are arbitrarily covered with black colored shade nets. However, their optimal growth conditions, especially light, are still less understood. During the investigation of different light qualities on the growth of Epimedium pseudowushanense, it was found that, all the values of plant growth characteristics (except shoot number) and photosynthetic characteristics were lower under red, yellow, or blue light treatment than under white light treatment. However, yellow light treatment had beneficial effects on shoot number, dry biomass (per plant) as well as net photosynthesis rate (Pn) and maximal apparent quantum efficiency (AQY) in E. pseudowushanense when compared with red or blue light treatment. More importantly, we found that E. pseudowushanense accumulated higher levels of bioactive flavonoids under yellow light treatment than under white, red, or blue light treatment. Furthermore, both RNAseq and qPCR analyses revealed that yellow light could highly up-regulate the expression levels of flavonoid biosynthetic genes, in particular CHS1, F3H1, PT_5, and raGT_5 that possibly contributed to the enhanced accumulation of bioactive flavonoids in E. pseudowushanense. Taken together, our study revealed that yellow light is the optimal light for the growth of E. pseudowushanense. Our results provided key information on how to improve the cultivation condition and concurrently enhance the accumulation of bioactive flavonoids in E. pseudowushanense.

Determination of the Effect of Shading Nets on Apple Fruit Quality

Amaç: Fuji elma çeşidinde farklı ışık geçirgenliğine sahip gölgeleme örtülerinin kullanımının meyve kalitesi üzerine etkisinin belirlemek amacıyla yapılmıştır.Materyal ve Metot: Bu çalışmada %10 ve %20 gölgeleme özelliği bulunan gölgeleme örtüleri kullanılmıştır. Kontrol uygulaması olarak, gölgeleme örtüsü bulunmayan açıkta yetiştiricilikyapılmıştır.Bulgular: En düşük ortalama meyve ağırlığı, %20 gölgeleme örtüsü altında yetişen ağaçlardan elde edilmiştir. Meyve eti sertliği açısından uygulamalar arasında önemli bir farklılık Bulunmazken, suda çözünür kuru madde miktarı %10 gölgelemede yetişen ağaçların meyvelerinde daha yüksek olmuştur. En iyi meyve kabuğu rengi ise, kontrol ağaçlarından elde edilmiştir. Araştırmanın en belirgin sonucu olarak meyvelerde meydana gelen güneş yanıklığı oranının azalması üzerine gölgelemenin olumlu etkisinin olduğu ortaya çıkmıştır. Kontrol ağaçlarının meyvelerinde %30 civarında olan güneş yanıklığının, %20 gölgeleme altında yetişenlerde %2 değerine düştüğü tespit edilmiştir.Sonuç: Denizli ilinde yapılan Fuji elması yetiştiriciliğinde %20 gölgeleme yapılması önerilebilir.

Qualitative and Quantitative Phytochemical Analysis and Antioxidant Properties of Leaves and Stems of Clinacanthus nutans (Burm. f.) Lindau from Two Herbal Farms of Negeri Sembilan, Malaysia

The objective of the study is to analyse the phytochemical content by quantitative and qualitative methods and to investigate the antioxidant properties on Clinacanthus nutans leaves and stems from different areas: Yik Poh Ling (YPL) un-shaded sample (exposed to direct sunlight) and You Dun Chao (YDC) un-shaded and shaded (with black shade netting) samples. Extracts were prepared by dissolving fine powder of C. nutans in 1:10 solvent using ultrasonic extraction for an hour. Preliminary screening and quantitative estimation of phytochemical (alkaloids, flavonoids, cardiac glycosides, saponins, steroids, terpenoids, phenols and tannins) analysis were conducted. Then, determination of antioxidant properties (total phenolic content, TPC, ferric reducing/ antioxidant power, FRAP and radical-scavenging activities, DPPH) were conducted. All the samples contained alkaloids, flavonoids, cardiac glycosides, saponins, steroids, terpenoids, phenols and tannins. Un-shaded leaves of C. nutans from YDC exhibited significantly higher result in antioxidant properties (966.00mg GAE/g of dried sample in TPC, 20.44mg TE/g of dried sample in FRAP and 11.14mg TE/g of dried sample in DPPH) than the other samples (p < 0.05). As a conclusion, C. nutans has a good potential to be an alternative antioxidant source.

Prevention of particulate matter and airborne culturable bacteria transmission between double-tunnel ventilation layer hen houses

Airborne bacteria and particulate matter (PM) emitted from animal houses may harm the environment and threaten on-farm and off-farm bio-security. Airborne transmission of PM and bacteria occurs more easily between double-tunnel ventilation layer hen houses with side-to-side arrangement due to the layout of inlet and outlet, and the accumulation of airborne contaminants in the intermediate region. This study practically applied shading nets for covering exhaust area and water disinfection for evaporative cooling system to prevent airborne transmission of PM and microbial aerosols between layer hen houses. Differences of PM and airborne culturable bacteria (CB) concentrations in control group and experimental group were used to evaluate the contaminants blocking effect of the treatment. PM and airborne microbial concentrations between houses were significantly higher than the upwind. Shading nets used as a barrier of PM and airborne bacteria had no significant effect on the reduction of inlet PM and airborne CB concentration of layer hen houses. The airborne CB concentration after evaporative cooling pads with water could be several times higher than that before. However, airborne CB concentration after the evaporative cooling pads with water disinfection was much lower than that before. Results indicated that shading net as a barrier of PM and airborne bacteria could hardly bring down contaminants concentrations near the inlet. Water disinfection for evaporative cooling system could largely reduce the inlet airborne CB concentration. Inlet air purification of animal houses is an effective way to prevent airborne microorganisms transmission.

Characterizing the convective heat exchange with plastic shading nets under natural arid conditions

Plastic nets are extensively used for shading purposes in arid regions such as in the Arabian Peninsula. Quantifying the convection exchange with shading net and understanding the mechanisms (free, mixed and forced) of convection are essential for analyzing energy exchange with shading nets. Unlike solar and thermal radiation, the convective energy, convective heat transfer coefficient and the nature of convection have never been theoretically estimated or experimentally measured for plastic nets under arid conditions. In this study, the convected heat exchanges with different plastic nets were quantified based on an energy balance applied to the nets under outdoor natural conditions. Therefore, each net was tacked onto a wooden frame, fixed horizontally at 1.5-m height over the floor. The downward and upward solar and thermal radiation fluxes were measured below and above each net on sunny days; also the wind speed over the net, and the net and air temperatures were measured, simultaneously. Nets with different porosities, colors and texture structures were used for the study. The short and long wave’s radiative properties of the nets were pre-determined in previous studies to be used. Re and Gr numbers were determined and used to characterize the convection mechanism over each net. The results showed that forced and mixed convection are the dominant modes existing over the nets during most of the day and night times. The nature of convection over nets depends mainly on the wind speed, net-air temperature difference and texture shape of the net rather than its color and its porosity.

Effects of Different Shading Rates on the Photosynthesis and Corm Weight of Konjac Plant

To study the effects of shading level on the photosynthesis and corm weight of konjac plant, the chlorophyll fluorescence parameters, daily variation of relative electron transport rate (rETR), net photosynthetic rate (Pn), and corm weight of konjac plants under different treatments were measured and comparatively analyzed through covered cultivation of biennial seed corms with shade nets at different shading rates (0%, 50%, 70%, and 90%). The results showed that with the increase in shading rate, the maximum photochemical efficiency, potential activity, and non-photochemical quenching of photosystem Ⅱ (PSⅡ) of konjac leaves constantly increased, whereas the actual photosynthetic efficiency, rETR, and photochemical quenching of PSⅡ initially increased and then decreased. This result indicated that moderate shading could enhance the photosynthetic efficiency of konjac leaves. The daily variation of rETR in konjac plants under unshaded treatment showed a bimodal curve, whereas that under shaded treatment displayed a unimodal curve. The rETR of plants with 50% treatment and 70% treatment was gradually higher than that under unshaded treatment around noon. The moderate shading could increase the Pn of konjac leaves. The stomatal conductance and transpiration rate of the leaves under shaded treatment were significantly higher than those of the leaves under unshaded treatment. Shading could promote the growth of plants and increase corm weight. The comprehensive comparison shows that the konjac plants had strong photosynthetic capacity and high yield when the shading rate was 50%-70% for the area.
 
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 In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue.
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Photo-selective shade nets on the production and quality of sugarcane plantlets

ABSTRACT Brazil is the world’s largest producer of sugarcane (Saccharum officinarum L.) and research aimed at propagation has promoted higher quality in production. The objective of this study was to investigate the effect of the variation of micrometeorological elements on the survival and quality of pre-sprouted sugarcane plantlets. The study was carried out in a protected environment (UFRPE). Plantlets of the cultivar RB92579 were obtained by the technique of production of pre-sprouted plantlets. The protected environments were divided into four modules covered with low-density polyethylene plastic + photo-selective shade nets and one module without shade net. Micrometeorological data of global and photosynthetically active solar radiation, air temperature, substrate temperature, relative humidity and the solar radiation spectrum were recorded in each module. The experiment was conducted in a completely randomized design and the principal component analysis was used to verify the association between the cultivation modules, micrometeorological variables and crop variables. Anti-UV low-density polyethylene plastic + freshnet led to lower transmittance of global solar radiation, higher percentage of photosynthetically active radiation and lower plantlet mortality. Substrate temperature above 30.2 °C resulted in higher plantlet mortality. Larger spectrum in the red range led to the production of better quality plantlet. The use of freshnet shade net promoted adequate conditions for the cultivation of sugarcane plantlets and allows obtaining better quality plantlets.

Effects of Wind Net Shading and Sprinkling on Growing Conditions and Fruit Quality in ‘Hongro’ and ‘Fuji’ Apple Fruits

Effects of Wind Net Shading and Sprinkling on Growing Conditions and Fruit Quality in ‘Hongro’ and ‘Fuji’ Apple Fruits

An experimental study on the improvement of indoor thermal environment of tents by shading in summer

Because of the simple structure and easy to carry, tents are widely used in military camps, rescue and disaster relief, site construction, tourism, nomadic people living and so on. However, the tent is very hot and humid in summer which seriously affects people’s rest and work. By the method of erecting a shading net on the top of the tent, the influence of solar radiation on the indoor thermal environment of tents in summer can be reduced. The indoor thermal environment of tents with different density shading nets was tested at a university campus of Tianjin, China. The experimental results showed that, comparing with the tent with no shading, the cooling effect of “six pins” net with shading rate of 96% is very good, the indoor temperature of the tent in summer can drop 8°C; while the indoor temperature of tent shaded by “three pins” net with shading rate of 75% can drop 5°C. The results also showed that: the internal surface temperature of the tent with shading nets can decrease about 12°C ∼17°C, the cooling effect is very obvious. The sun shading is conducive to improve the thermal environment of the tent.

Horticultural Aspects for the Cultivated Production of Piquin Peppers (Capsicum annuum L. var. glabriusculum)—A Review

Piquin pepper [Capsicum annuum L. var. glabriusculum (Dunal) Heiser and Pickergill] is a semidomesticated pepper with high commercial value and wide applications as fresh or processed products. Piquin pepper plants have been difficult to domesticate and cultivate because of low seed germination, genetic and morphologic variability, insect and disease susceptibility, and limited environmental physiology information. Currently, seed sterility is no longer considered a limiting factor as hormonal, chemical, and thermal treatments have been developed to overcome seed dormancy. In vitro propagation (primarily by direct organogenesis) is still not reliable for seedling production. Cropping systems of piquin pepper plants include traditional methods such as agroforestry and full sunlight, and under protected horticulture conditions, mainly shade nets. Shade levels and water availability affect yield and vegetative growth. Piquin pepper plants can be grown under diverse geographic and edaphic conditions. Nutrition and fertilization studies are limited. Biotic stresses that can cause economic damage to piquin pepper plants include most that affect other pepper cultivars. Piquin pepper is also considered an important genetic resource as it reports resistance to some viral groups, which could be used for genetic improvement of other cultivated peppers. Current research needs involve the development of dependable plant materials (cultivated varieties) with reduced labor needs, particularly during the harvest period. In addition, research is needed to reduce the susceptibility of piquin pepper plants to other plant diseases. This review presents an analysis of the aspects related to the production of piquin peppers under cultivated conditions.

Comportamiento agronómico de ecotipos de chile piquín bajo cubiertas fotoselectivas

<strong>Introduction:</strong> The use of colored shading nets and greenhouses is a strategy to improve the use of solar radiation and regulate temperature, in addition to increasing productivity in horticultural crops.<br /> <strong>Objective:</strong> To evaluate the effect of different photoselective covers on agronomic variables in wild piquin pepper ecotypes.<br /> <strong>Methodology:</strong> Microclimatic variables and photosynthetically active radiation (PAR) were measured from plant transplant, and agronomic variables at 40 days after transplant and at the last cut of the cycle (160 days).<br /> <strong>Results:</strong> Temperature, relative humidity and PAR changed with the use of the different covers. Blue netting reduced PAR by 50.10 % compared to the open field. Principal component analysis grouped the uncovered cultivated plants with the lowest results in the evaluated variables, and the RTZ ecotype revealed the greatest tendency towards quadrant 1, with most of the variables. The yield in the white netting increased 1 290.9 % compared to that obtained in the field. <strong>Study limitations:</strong> The study generated information only for the plant genetic resources of the Northeast Region of Mexico.<br /> <strong>Originality:</strong> The crop is not domesticated, so this work was done under different shade netting covers and a greenhouse.<br /> <strong>Conclusions:</strong>White netting favored the development of the ecotypes, with RTZ being the one that presented the best values, which is why this combination is considered viable for the preservation and production of this species on a large scale.

The effect of light variations by photoselective shade nets on pigments, antioxidant capacity, and growth of two ornamental plant species: Marigold (Calendula officinalis L.) and violet (Viola tricolor)

A new group of colored shade net has been developed that can influence the quality and quantity of the light intercepted by the plants. To explore the effect of applying colored shade nets on physi...

Effect of coloured shade nets on growth and frond production in sword fern (Nephrolepis cordifolia)

Effect of coloured shade nets on growth and frond production in sword fern (<i>Nephrolepis cordifolia</i>)

Anatomical modifications of Butia capitata propagated under colored shade nets.

The jelly palm plant [Butia capitata (Martius) Beccari] is a native palm of the Cerrado biome used for many purposes in northern Minas Gerais State, Brazil. Dormancy is common in palm seeds, resulting in slow and uneven germination that may take years to complete. Modification in the growth pattern, anatomical parameters, physiological and biochemical characteristics of the plant can be verified due to changes in the light spectrum transmitted through colored shade nets used. Therefore, the objective of this study is to evaluate the effect of colored shade nets on the leaf and root anatomy of the jelly palm plant. The experiment was performed in a completely randomized design, with five treatments, ten replicates and eight plants per replicate, totaling 400 plants. Four colored photo-converter nets with 50% shading and different radiation proportions were employed: white (985 μmol.m-2.s-1), red (327 μmol.m-2.s-1), black (433 μmol.m-2.s-1) and silver (405 μmol.m-2.s-1). The plants cultivated under direct sunlight (1000 μmol.m-2.s-1) were considered as the control group. Leaf and root anatomical analysis was performed on 10 plants per treatment. It is possible to conclude that the colored shade nets caused changes in leaf and root anatomy of the jelly palm plant (Butia capitata).

Biomass and Biogas Yield of Maize (Zea mays L.) Grown under Artificial Shading

Agroforestry, as an improved cropping system, offers some advantages in terms of yield, biodiversity, erosion protection or habitats for beneficial insects. It can fulfill the actual sustainability requirements for bioenergy production like food supply, nature conservation, stop of deforestation. However, competition between intercropped species for water, nutrients and light availability has to be carefully considered. A field trial with shading nets was conducted in Southwest Germany to evaluate the influence of different shading levels (−12, −26, and −50% of full sunlight) on biomass growth, dry matter yield and biogas quality parameters of maize (Zea mays L., cv. ‘Corioli CS’). Shading the plants causes a delayed development, a reduction in height and leaf area index and a slower senescence. Dry matter yields were reduced about 18%, 19%, and 44% compared to 21.05 Mg ha−1 year−1 at full sunlight. Biogas and methane yields were also significantly reduced, the 50% shading treatment showed a reduction of 45% for both parameters. Further, shading led to higher crude protein and crude ash contents. If silage maize is grown under shade, the yields of dry matter, biogas, and methane are nearly halved under 50% shade. Cultivation up to 26% shading could be possible.

Shade netting reduces sunburn damage and soil moisture depletion in ‘Granny Smith’ apples

The benefits associated with the use of protective netting for apple orchards have been assessed in several growing regions, but no studies exist for Washington State, USA. This region experiences semi-arid conditions characterized by long days, high light intensity and high temperatures which increases the risk of plant stress and fruit sunburn damage. The aim of this study was to assess the effect of anti-hail nets on orchard microclimate, soil moisture and fruit sunburn. Seven-year-old ‘Granny Smith’/‘M9-T337’ apple trees were covered in 2014 with 20% white shade net sheltering a rectangular area. Uncovered trees served as control. Shade net reduced the maximum daily photosynthetically active radiation (PAR) by 32%, with a maximum PAR value on a sunny day of 1649 and 1222 μmol m-2 s-1 in the control and netted areas, respectively. Canopy air temperature was slightly lower during the day and higher at night under the net compared to the control. Shade nets reduced soil moisture depletion at 0-30 cm depth, resulting 20% higher than the control. No significant differences were observed deeper in the soil profile. Netting significantly decreased fruit sunburn, with 92% of harvested fruit having no sunburn damage compared to control in which 51% had no sunburn damage in 2014. Although preliminary, these results show that shade netting has the potential to reduce sunburn damage in ‘Granny Simith’ apples and water requirements in semi-arid environments and might represent an important tool for increasing yields of high quality fruit.

Effect of wind speed and direction on forces acting on shade nets covering orchard trees

The use of nets and screens to cover orchards has greatly expanded during the last decade, since the nets protect the trees from excessive radiation, strong winds, hail and insects. Furthermore, recent studies have shown that, in certain orchards, the nets can significantly reduce the water consumption of trees. The nets are usually stretched above the trees and are fixed to the supporting poles by cables that run all around the net circumference. In this study, experiments were done to determine the forces acting on a horizontal shade net that covered an orchard (232×100 m(2)) in which peach trees were grown. A net section of 40×6 m(2), at an upwind edge of the net-house, was used to measure the forces. Sixty load cells that were evenly distributed on the section circumference were used to attach the net to the net-house cables. Results show that the force acting on the net at the point where the load cell is attached to the net is a second-order polynomial of wind speed. The forces acting on the net were stronger at the points where the net was attached to a cable at the outer edge of the net-house. At points where the net was attached to inner cables of the net-house, the forces were smaller. Extrapolating the second-order polynomial, it was shown that, at a wind speed of 150 km h(-1), the largest force acting at the point where the load cell was attached to the net could be 50 kg.

Testing the effect of different light environments and water shortage on apple physiological parameters and yield

The effect of different light environments on 'Imperial Gala' apple yield and several physiological parameters were evaluated in 2013 by placing over the trees nets with different levels of shading and colour (black, 20% shading, red and white, 50% shading). A fourth plot was left uncovered. Each net was combined with two irrigation treatments for 60 days before harvest: no stress and moderate stress. Irrigation was applied to achieve specific levels of water stress and was managed using midday stem water potential (mSWP) thresholds. mSWP was measured weekly from the onset of the irrigation treatments until harvest. Leaf gas exchanges were assessed three times during that period. Crop water requirements were estimated as crop coefficient values (Kc) from measurements of tree light interception three times during the season. Water stress reduced mSWP and leaf photosynthesis. Shading level and colour did not affect leaf photosynthesis but the uncovered plot had the highest Kc and the most negative mSWP (values around -1.3 MPa). The black net (20% shading) had an intermediate Kc and mSWP between trees without nets and trees with 50% of shading. The red and white nets had the same Kc and maintained mSWP around -1.0 MPa indicative of no water stress in apple. At harvest, marketable yield was higher for the shaded trees compared to uncovered trees for both irrigation treatments indicating that apple trees without nets were grown in more stressed conditions. This leads to think that under moderate water conditions before harvest net shading may be useful to maintain acceptable marketable yields. Conditioning the available light inside the orchard with the use of shading nets could be therefore a promising horticultural technique to face future challenges related to low water availability in fruit orchards.

Cultivar-specific responses in red sweet peppers grown under shade nets and controlled-temperature plastic tunnel environment on antioxidant constituents at harvest

Antioxidant constituents such as carotenoids (capsanthin, phytoene, lutein, β-cryptoxanthin), polyphenols content (p-coumaric, ferulic, p-hydroxybenzoic, caffeic acid, sinapic acid, and quercetin-3-glucoside) and marketable yield were investigated in 11 sweet pepper cultivars grown under controlled temperature plastic tunnel and white shade net. Marketable yield was not affected by either of the environments, while the interaction between cultivar and growing environment significantly affected the accumulation of antioxidant constituents. The principal component analysis illustrated that controlled temperature plastic tunnel improved the accumulation of carotenoid components and ascorbic acid and vitamin C content in most cultivars. On the contrary, white shade nets favoured the accumulation of phenolic compounds and ORAC activity in most cultivars. A strong correlation was noted between phytoene and carotenoid components in this study (capsanthin r = 0.60; P < 0.001; lutein r = 0.75; P < 0.001; β-carotene r = 0.78; P < 0.001) while ORAC correlated with phenolic compounds. Based on this study, it is possible to refine the choice of environment and cultivar to enhance individual antioxidant constituent groups to improve health benefits for consumers.