Photoselective Nets Research Articles

Does photoselective netting influence ripening, maturity parameters and chemical composition of highbush blueberry (Vaccinium corymbosum L.) fruit?

The use of photoselective nets in highbush blueberry orchards has attracted much interest in recent years. In our 2-year experiment, we evaluated the effect of black, red, yellow and white exclusion nets and an uncovered control on light quantity and quality, fruit maturity parameters and chemical composition at harvest. Significant differences between treatments were noticed in fruit peel color, firmness and total soluble solids (TSS) content in both experimental years. The content of total volatiles in 2022 was the highest under the red net (2.67 mg kg−1) and the control (2.63 mg kg−1), to which the contents of hexanal and (E)-2-Hexenal contributed the most. No significance in total volatiles was determined in 2023. The sugar/organic acid ratio was the lowest in fruit under the yellow net (4.62) and the highest under the black net (7.74). Total phenolic, total anthocyanin and petunidin-3-O-glucoside contents were the highest in fruit under the black net (3606 mg kg−1) and lowest in fruit under the white exclusion net (2072 mg kg−1). According to our results, the black net performed the best, regarding the internal quality parameters, while the yellow net negatively affected the sugar/organic acid ratio and the white exclusion net negatively affected the total phenolic content.

Can Photoselective Nets' Influence Pollen Traits? A Case Study in 'Matua' and 'Tomuri' Kiwifruit Cultivars.

The increasing use of photoselective nets (PNs) raises the question of their influence on pollen traits. We aimed to evaluate the effect of PNs (yellow, pearl, and grey) on the pollen of 'Matua' and 'Tomuri' Actinidia deliciosa cultivars. The pollen size and the exine were studied with a light microscopy and a scanning electron microscopy, and the fertility was analysed by a viability assay and in vitro germination. The total soluble proteins (TSPs) and sugars (TSSs) were quantified by colorimetric assays. The molecular structure of the pollen grain's wall was analysed by a Raman spectroscopy. The pollen from the plants under the PNs had a larger width and area and a lower germination rate. No significant changes were observed in the exine's microperforations. The TSP and TSS contents were influenced by the cultivar and PNs (particularly the pearl PN). The Raman spectra of the pollen from the plants grown under the nets presented some bands that significantly shifted from their original position, indicating differences in the vibration modes of the molecules, but no overall changes at their structural or organisation level were found. Our study showed that the PNs could influence several pollen traits, with the pearl PN inducing greater modifications. Our results also support the idea that cultivars affect the outcome of some characteristics.

Sparse-shading red net improves water relations in Valencia orange trees

Top-netting technology improves crop microclimate, and its utilization in fruit tree plantations may mitigate deleterious weather effects. The technology is associated with improved tree water relations, and may result in significant water savings. Photoselective nets may provide additional, crop- and target-dependent, beneficial effects. A previous paper reported results of a five-year trial in Valencia orange, in which three nets were used, pearl, transparent and low shading red, in combination with three irrigation regimes, 100% (I100), standard commercial fertigation, and two reduced rates, 80% (I80) and 60% (I60). Among the different netting types, the combination of red nets and I80 resulted in the highest yield on a multi-annual basis. The current study provides data regarding water relations during stage II, i.e., cell expansion, of fruit development. The red net had higher radiation transmittance and canopy resistance than the pearl net. The higher resistance is an expression of the lower transpiration of the red net, monitored by sap flow, as compared to the other treatments, especially under deficient irrigation. The beneficial effect of the red net was also evidenced from multi-annual stem water potential. These data supplement the enhanced yield effect of the red net, suggesting they are associated with its spectral properties.

Effects of Four Photo-Selective Colored Hail Nets on an Apple in Loess Plateau, China

Hail, known as an agricultural meteorological disaster, can substantially constrain the growth of the apple industry. Presently, apple orchards use a variety of colored (photo-selective) hail nets as a preventative measure. However, it is unclear which color proves most effective for apple orchards. This study provides a systematic investigation of the impact of four photo-selective colored hail nets (white, blue, black, and green; with white being the control) on the microenvironment of apple orchards, fruit tree development, fruit quality, and yield over a two-year period (2020–2021). Different photo-selective nets do not evidently alter the intensity of light, although the nets’ shading effects decrease in the order from black to green to blue. Among them, blue nets increased the proportion of blue light, while green nets enhanced the proportion of green light. On the other hand, black, green, and blue nets diminished the proportion of red and far-red light. Such photo-selective nets effectively lowered soil temperature but did not have an impact on relative humidity and air temperature. Encasing apple trees with blue nets promoted growth, increasing shoot length, thickness, leaf area, and water content, while simultaneously decreasing leaf thickness. Black nets had comparable effects, although the impacts of green nets were inconsistent. Different photo-selective nets did not significantly influence the leaf shape index or overall chlorophyll content. However, black and green nets reduced the chlorophyll a/b ratio, while blue nets slightly boosted this ratio. Additionally, blue nets proved beneficial for apple trees’ photosynthesis. With the employment of a principal component analysis and comprehensive evaluation, this study concludes that blue nets offer the most favorable environmental conditions for apple growth while protecting apple orchards against hail, compared to black, white, and green nets.

Effects of shading nets as a form of adaptation to climate change on grapes production: a review

Viticulture worldwide is threatened by the environmental modification caused by climate change. Higher temperature and atmospheric CO2 concentration determine an acceleration of the ripening process, which can be detrimental to wine quality. Hence, adaptation and mitigation strategies are necessary to reduce heat and water stress and improve the qualitative production levels. Amongst all the various techniques available, shading nets represent an interesting alternative for their effects on canopy microclimate and grape production. However, these effects vary strongly depending on the intensity of the shading treatment, the timing of its application, environmental conditions, and differences in cultivar response. The reduction in photosynthetic activity can improve water use efficiency and slow down the ripening process, preserving must acidity. Phenolic compounds, which benefit from light exposure for their synthesis, are negatively affected by shading, while aromatic composition can be improved by it. Vine reserve accumulation is reduced by the lower photoassimilates production. Photoselective nets, thanks to their colour, not only reduce light intensity but also change the quality of the light spectrum reaching the canopy, thus, determining specific responses in the plants.

Effect of Photo-Selective Nets on Yield, Fruit Quality and Psa Disease Progression in a ‘Hayward’ Kiwifruit Orchard

The influence of the colour of photo-selective nets on Actinidia deliciosa yield, fruit quality and progression of the bacterial kiwifruit canker (Pseudomonas syringae pv. actinidiae, Psa) need to be characterised due to increasing use of these nets, mainly to protect from hail and storms. From May 2019 onwards, pearl (Pn), yellow (Yn) and grey (Gn) nets were installed permanently in a ‘Hayward’ kiwifruit orchard in NW Portugal and uncovered plants were used as the control. Compared to outside conditions for both seasons, the blue:red ratio and the mean air temperature were higher (mean increase of 12.7% and 0.6 °C, respectively) and the photosynthetic active radiation (PAR) was lower (10.8% less between budbreak and bloom) under the Pn. Crop yield, compared to the control, decreased by 40.3% under the three nets in 2020, and by 23.9% under the Yn and Gn in 2021. Yield and fruit grade under the Pn were similar to that of uncovered crops in 2021, and fruit grade was overall higher under the Pn compared to the Yn and Gn. Photo-selective nets did not affect the fruit quality parameters. Psa progression decreased under the Pn compared to the control during two months in both seasons, although this beneficial impact needs further evaluation.

Effects of photo-selective nets and air humidity coupling on tomato resistance to Botrytis cinerea

Light quality and air humidity play a vital role in plant-pathogen interactions, which profoundly affect the occurrence of crop disease. However, the effect of light quality and air humidity coupling on the interactions between tomato and Botrytis cinerea remains unclear. In this study, 2 humidity levels and 3 colors of photo-selective nets were used to determine the infection process of B. cinerea and the response of plants to pathogen infection. Results showed that low air humidity inhibited the mycelial growth of B. cinerea, and red and blue nets could effectively delay the formation time of pathogen infection structure and reduce the disease incidence. Under high humidity, the reduction of net photosynthetic rate of infected plants was caused by non-stomatal restriction, whereas the changes in light quality by red net reduced the damage of pathogen to tomato photosynthetic structure and improved the photosynthetic capacity of tomatoes. Low air humidity and red net coupling (LR) treatment slowed down the decline of Fv/Fm, ΦPSⅡ and qP; inhibited the increase of malonaldehyde and reactive oxygen contents; increased the activities of antioxidant enzymes in tomato plants; and promoted the quality and yield of fruits. The LR treatment inhibited the infection process of B. cinerea, alleviated the disease severity, improved the photosynthetic and antioxidant capacities, and maintained the fruit quality and yield of tomatoes.

Sustainable Food Production: Innovative Netting Concepts and Their Mode of Action on Fruit Crops

Net application in agriculture has a long history. Nets were usually used for the protection of plants against different hazards (hail, wind, birds, pests, excessive sun radiation) and, lately, from insects (nets with smaller mesh size). In recent years, photoselective netting technology has emerged, which adds desired plant responses caused by light quality changes to their basic protective properties. A combination of anti-insect and photoselective net technology (anti-insect photoselective nets) may present a notable contribution to the sustainable food production concept. Notable positive effects of this eco-friendly approach on agroecosystems are mainly achievable due to its non-pesticide pest protection of cultivated plants and, at the same time, promotion of special beneficial morphological and physiological plant responses. Although netting has been extensively studied over the last decade, there is a pronounced lack of publications and analyses that deal with their mode of action on fruit trees, which is especially true for new netting concepts. A better understanding of such mechanisms can lead to improved development and/or utilization of this technology and enhanced generation of value-added products. This review was based on a revision of the literature regarding netting in agriculture, with emphasis on fruit cultivation, and the following databases were used: Web of Science, ScienceDirect, Scopus, and Google Scholar. Although this study aims to comprehend a majority of fruit species, it narrows down to those usually net-protected and, hence, studied, such as apple, peach or nectarine, kiwifruit, blueberry, etc. Nets mainly differ in their mesh size and color, which are the parameters that mostly determine their capacity for light quantity and quality modification. Such light modifications, directly or indirectly (e.g., change in microclimate), initiate different fruit tree responses (in some cases, mechanisms) through which the final effect is realized on their vegetative and generative traits. For instance, some of them include a shade avoidance mechanism (initiated by changes in red to a far-red ratio, blue light levels, etc.), source–sink relationship, and carbohydrate availability (actualized by changes in photosynthesis efficiency, vegetative and generative growth, etc.), plant stress response (actualized by microclimate changes), etc. In most cases, these responses are interconnected, which contributes to the complexity of this topic and emphasizes the importance of a better understanding of it.

The roles of different photoselective nets in the targeted regulation of metabolite accumulation, wine aroma and sensory profiles in warm viticulture regions

To improve the quality of grapes and wine in warm viticulture regions, the effects of pearl, red and black photoselective nets on the quality of grapes and wine were systematically investigated. Compared with the CK (open field), three nets improved the microclimate conditions and reduced grape sugar and wine alcohol levels. However, the nets differentially affected other quality profiles of the grapes and wine. The pearl net reduced the total flavanol contents in grapes and total aromatic volatiles in wine. The red net increased the total flavanol, tannin and total aromatic volatile contents in wine by approximately 40%, 95% and 10%, respectively, and the percentages for the black net were 30%, 45% and 3%, respectively. The red and pearl nets were more inclined to improve the taste and aroma sensory qualities of wine than the black net did. The red net had the highest comprehensive scores via principal component analysis.

Photo-selective nets influence physiology, growth, yield and quality of turmeric (Curcuma longa L.)

Turmeric (Cucruma longa L.) grown under various photo-selective nets, sprayed with different elicitors manifested significant differences in growth, yield and quality during both the years of experimentation. The pooled data over two growing seasons clearly revealed that, turmeric under red photo-selective net with chitosan at 1000 ppm manifested highest plant height (106.50 cm) and number of leaves (22.99). While, plants grown under blue photo-selective net without any elicitors outperformed as compared to other treatment combinations in respect of number of tillers per plant (6.58). Yellow net with salicylic acid at 100 ppm recorded highest leaf area (5602.8 cm2 plant−1). The blue net with 1000 ppm chitosan resulted in maximum chlorophyll content (SPAD value 42.11). The yellow photo-selective net had a most positive impact on the major yield determinant, the number of primary rhizomes per plant (16.68), while the metabolic elicitors had no influence. Yellow net was superior in terms of fresh (58.27 t ha−1) and cured rhizome yield (15.53 t ha−1) and none of the elicitors had any significant influence on yield. The dry recovery was highest in yellow net and sprayed with active dry yeast at 5000 ppm (27.78%). Curcuminoid content, the major quality determinant was highest in blue net (5.09%) sprayed with chitosan at 1000 ppm. Provision of yellow photo-selective net (25% shade) along with 5000 ppm active dry yeast applied at monthly interval starting from one month after planting up to five months after planting could be recommended for obtaining highest yield and better quality turmeric with highest net returns. Farmers growing turmeric crop under open field condition may spray salicylic acid at 100 ppm to realize higher yield and net returns.

Modulation of Light and Nitrogen for Quality-Traits Improvement: A Case Study of Altino Sweet Pepper

Local varieties are known to cope more efficiently with stressful and/or low-input conditions than cultivated ones by activating secondary metabolisms and, hence, are supposed to have higher nutraceutical potential. In this work, we investigate the effects of N and light, supplied at optimal and sub-optimal levels, on the fruit yield and quality of a local ecotype of sweet pepper, Altino, grown in the Abruzzo Region (Southern Italy). In 2017, two open-field experiments were carried out, comparing increasing N rates (0, 100 and 200 kg N ha−1, 0_N, 100_N and 200_N, respectively) and different percentages of shading and/or manipulations of the transmitted solar radiation, obtained through photoselective nets (red net, RN; black net, BN; unshaded Control). Both N and light were preconditions to obtain stable yields in terms of both fruit number and fruit weights. However, BN significantly reduced the number of sunscalded fruits (0.39 vs. 3.38 and 2.59 fruit plant−1 for BN, Control and RN, respectively), leading to lower waste. N deficiency favoured higher total polyphenol (TPC) and flavonoid (TFC) contents in ripened fruits; on the other hand, shading significantly reduced TPC (−12.4%) in immature and TFC (−18.2%) in red fruits. The variations in nutraceuticals were also evaluated in terms of the variations of the single phenolic acids in fruits during ripening; the most interesting results were associated with light treatments. Further research should be directed to the in-depth study of nutrition regimes, in combination with other photoselective nets applications (i.e., pearl nets), that could be suitable for the Altino genotype to enhance the yield and nutraceutical potentials of its fruits.

Effects of photo-selective netting in Summer Beefsteak Tomato (Solanum lycopersicum L.) cultivation on the environmental conditions under nets as well as growth and yield

Located in a subtropical zone, Taiwan has intense summer sunlight that affects beefsteak tomato cultivation. In this study, beefsteak tomatoes were grown net-house under photo-selective netting of different colors to investigate netting performance. A significantly higher photosynthetic photon flux density (PPFD) was observed under the 24-mesh white (W24) and 24-mesh pink (H24) netting. A difference between the four net-house was only observed for wavelengths of 500–599nm. In 32-mesh blue (B32), the red to blue (R/B) and red to far-red (R/FR) ratios were significantly lower across canopies. The photosynthetic capacity of photosystem II of leaves in W24 was the lowest among the four treatments. In all four, fruit growth was relatively low under the impact of high temperatures, with the lowest single fruit weight and the smallest number of fruits per plant observed in W24. In H24 and 24-mesh pink (HH24), the yield per plant was significantly higher. Significantly fewer whiteflies were observed in the netting houses in H24, HH24, and B32 than in W24. However, the netting still failed to prevent high temperatures at noon. In H24 and HH24, the amount of light retained in the canopies was greater, the photosynthesis capacity was unchanged, the fruit yield was greater and the number of whiteflies in the netting houses was significantly lower. Therefore, pink netting is recommended for beefsteak tomato cultivation.

Effect of yellow and Stop Drosophila Normal anti-insect photoselective nets on vegetative, generative and bioactive traits of peach (cv. Suncrest)

The effect of anti-insect photoselective yellow (Tenax (Italy); mesh size of 2.4 · 4.8 mm) and Stop Drosophila Normal (Artes Politecnica (Italy); mesh size of 0.90 · 1 mm) nets on the generative and vegetative traits of peach 'Suncrest' was studied at an orchard near the city of Čakovec, Croatia. Netting significantly affected some vegetative parameters (leaf surface, leaf length and leaf shape index) but there was no significant effect on productivity parameters (yield, yield efficiency, fruit mass and share of decayed fruit). Application of nets significantly affected b* and C* fruit background colour parameters and L*, b*, C*, h° fruit additional colour parameters. Nets significantly affected majority of inner fruit quality parameters (fruit firmness, titratable acidity and total soluble solids / titratable acidity ratio) as well as of bioactive compounds (total polyphenolic content, antioxidant activity, anthocyanin content and share of alkali-soluble pectin). Since application of yellow net only slightly reduced peach fruit quality (in contrast to control) it can be recommended for application as an anti-insect net. However, it cannot be said for Stop Drosophila Normal net because it more notably reduced quality parameters (especially additional fruit colour).

Effect of Photo-Selective Nets and Air Humidity Coupling on Leaf Anatomical Structure, Photosynthetic Characteristics and Fruit Quality of Tomato Resistant to Botrytis Cinerea

Effect of Photo-Selective Nets and Air Humidity Coupling on Leaf Anatomical Structure, Photosynthetic Characteristics and Fruit Quality of Tomato Resistant to Botrytis Cinerea

Effect of Photo-Selective Nets on Yield, Fruit Quality and Psa Incidence in a ‘Hayward’ Kiwi Orchard

Effect of Photo-Selective Nets on Yield, Fruit Quality and Psa Incidence in a ‘Hayward’ Kiwi Orchard

Generative and Vegetative Traits of the 'Granny Smith' Apple Grown under an Anti-Insect Photoselective Red Net

Anti-insect photoselective nets present a new technology that combines light manipulation and pest protection in orchards. In this study, the effect of the anti-insect photoselective red net on the generative and vegetative traits was studied in an apple orchard near the city of Zadar, Croatia. 'Granny Smith' apples were grown on M9 rootstock and raised as slender spindles. The experiment consisted of two treatments: the trees covered with the red photoselective anti-insect nets (AGRITECH S. r. l., Eboli, Italy; mesh size of 2.4 × 4.8 mm) and uncovered trees as control. Yield, percentage of fruit with diameter >70 mm and fruit mass were not significantly different between treatments. L* color value was higher on fruit skin grown under the red net, and there was no significant difference in other color values (a*, b*, C* and h°). Soluble solids concentration (SSC) and total flavonoid content were significantly lower in fruit grown under red net than in control, and there was no significant difference in titratable acidity (TA), SSC/TA ratio, starch degradation and Streif maturity index. Red net proved to be effective against fruit red blush development (undesirable trait for 'Granny Smith' apple) and sunburn damage occurrence.

Pigments in flower stems of lisianthus under different photoselective shade nets

Abstract The lisianthus culture is demanded to produce cut flowers and pot vases, grown in a greenhouse using advanced techniques. The present study aimed to evaluate the pigments of different lisianthus cultivars in different photoselective shade nets. The cultivars Flare Deep Rose (pink), Echo Blue BL (purple) and Allemande White BI (white) were cultivated under light-diffusing polyethylene film cover and blue and red color photoselective nets with a shading capacity of 30%, in addition to the control treatment, without the use of the net. The results showed higher values of chlorophyll b and total in the red photoselective net, independent of the cultivar. Leaf colorimetry showed the most intense shade of green was from the cultivar Echo Blue BL. On the other hand, the control showed more intensity, with no significant difference in the leaf green intensity on the blue and red shade nets. In the petals, the cultivar Echo Blue BL showed a more intense blue shade in the red net, however low grade of anthocyanin than in the blue one. In the anthocyanin pigment, this cultivar had lower levels in the treatment of the red net. The results indicate that the use of photoselective shade nets in the culture of lisianthus changes the content of the pigments studied, in varying intensity, depending on the cultivar.

Top Photoselective Netting in Combination with Reduced Fertigation Results in Multi-Annual Yield Increase in Valencia Oranges (Citrus sinensis)

Fruit tree production is challenged by climate change, which is characterized by heat waves, warmer winters, increased storms, and recurrent droughts. The technology of top netting may provide a partial solution, as it alleviates climatic effects by microclimate manipulation. The tree physiological performance is improved under the nets, with an increased productivity and quality. The application of photoselective nets, which also alter the light spectrum, may result in additional horticultural improvements. We present the results of a 5-year experimental study on Valencia oranges, examining three nets: red, pearl, and transparent. Each net was tested at three fertigation conditions: a field standard (100%, I100) and two reduced fertigation regimes, which were 80% (I80) and 60% (I60) of the standard. The average multi-annual yield under the red and pearl nets with I100 and I80 and transparent net with I100 was significantly higher than that of the control trees. While the multi-annual yield increase under the red net I80 was due to the increase in the fruit number, in other treatments, the effect was mostly due to induction in the individual fruit weight. The data presented here show that an increased productivity of orange trees grown under photoselective nets, particularly the red net, with its specific spectral properties, was achieved with a considerable water-saving effect.

Photo-selective nets (PSNs) affect predation by Harmonia axyridis on Myzus persicae

Photo-selective nets (PSNs) can increase agricultural crop production by modifying the quantity and quality of light that reaches the plants. PSNs also have the potential to affect arthropod pest populations and their natural enemies. The present study aimed to assess the impact of PSN systems on coccinellid predation. Experiments were carried out in microcosm conditions to evaluate the efficiency (prey localization and predation) of the multicolored Asian lady beetle, Harmonia axyridis (Pallas), when preying on the green peach aphid, Myzus persicae (Sulzer), on potato plants. Three colors of nets were tested and compared to control (no net): black SN (standard net), pearl PSN, and red PSN, using H. axyridis third-instar larvae (L3), females and males. We hypothesized that pearl and red PSN and black SN would alter the predator behavior, delaying the time to aphid colony localization, or by reducing overall aphid predation. Our results showed that aphid colonies were not affected by any PSN or the black SN in the absence of predators. Aphid colony localization by adult coccinellids was delayed under black SN, and favored under pearl PSN, but overall aphid predation was unaffected by net type. There were no significant differences among treatments in interplant movement of L3, females, or males. We conclude that, under laboratory conditions, pearl PSN, red PSN, and black SN can affect aphid colony localization by H. axyridis, but do not affect predation efficiency. Subsequent trials in the field would be required to further clarify the effects of PSNs on H. axyridis foraging behavior.

Photoselective Nets Alter Apple Canopy Air Temperature and Carbon Translocation during Dormancy and Budbreak

Photoselective nets were used to examine apple shoot physiology during dormancy and budbreak. Two trials were conducted: one in the field and one in controlled conditions. In the first, three colored nets (red, blue, and white, shading 20%) covered sections of single trees, leaving an empty portion as control, from December to April. The white net increased canopy air temperature compared with the blue one. Differences were found in carbohydrate seasonal patterns; however, it appeared that soil temperature had higher impacts on sugar movement in the trees. No differences were found in bud phenology. In the second trial, cuttings were placed in boxes constructed with the same-colored nets and monitored from the end of February to April. Results showed differences in phenology and carbohydrate translocation. The white box hastened bloom and its cuttings had higher amounts of carbohydrates at the end of the trial. On the contrary, the blue box delayed bloom while resources were still being consumed and its cuttings had the lowest amounts of reserves at the end of the trial. These results add new insights on apple physiology under different light spectra and commercial applications should not be excluded for improving crop management.