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ColorNets: A new approach for light manipulation in fruit trees

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Abstract

We introduce here a new approach for improving the utilization of solar radiation by fruit trees. This approach is based on selective filtration of the light by plastic shade nets (cloths) with special optical properties that modify the quality of natural radiation. A series of colored shade nets (ColorNets) were developed to specifically modify the incident radiation (spectrum, scattering and thermal components). Depending on the pigmentation of the plastic and the knitting design, the nets provide varying mixtures of natural, unmodified light, with spectrally modified scattered light. Use of the nets aims to optimize desirable physiological responses, in addition to providing physical protection. Following the substantial effects of several ColorNets on shoot elongation, branching and flowering in ornamentals (Oren-Shamir et al., 2001), we have applied the colored netting to deciduous fruit trees. The experiments were carried out in commercial apple and peach orchards, using ColorNets with reduced shading factors (15-30%, compared with the 50-80% used in ornamentals). The first year results show positive effects on flowering, fruit-set, fruit size, colour and internal quality, in addition to non-specific reduction of water stress, superficial damage, and sunburn. This approach opens new perspectives for improved performance of fruit tree orchards under specialized protection.

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... Често се използват засенчващи мрежи над културите за намаляване на топлинния стрес (Shahak et al., 2004;Elad et al., 2007;Retamales et al., 2008). ...
... Shading nets over crops are often used to reduce heat stress (Shahak et al., 2004;Elad et al., 2007;Retamales et al., 2008). ...
... The observed values of the temperature factor show higher values during the colder months of the year (at the beginning of the growing season) and lower values during the hottest months of the year. The opinion of many authors that shading nets over crops reduce heat stress was undoubtedly confirmed (Shahak et al., 2004;Elad et al., 2007;Retamales et al., 2008) Of course, in order to fully assess the effect of shading and entomological network on cultivated plants, it is necessary to analyze the other abiotic factors and their interaction. ...
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Growing fruit species through sustainable environmental practices was considered as promising alternative to meet the challenge of various biotic and abiotic stresses threatening the production of fruit and planting material in climate change. Nowadays, various types of nets (shading, entomological, etc.) were used worldwide to protect plant species against environmental conditions, including hail, wind, excess sun light and pests, while improving plant health and quality of the fruits. During the period 2019-2020, in Fruit Growing Institute, Plovdiv a research was conducted to trace the changes, variations and trends of the main climatic factor -- temperature in the production of fruit planting material grown in conditions of shaded field, insects-proof net house and open field (area). In observation of changes in temperature (t,C) its average monthly value was considered. The change of the average annual temperatures in the observed fields showed higher values during the winter and spring months in the insects-proof net house, compared to the reported outdoor temperatures. In a shaded field, lower temperatures were observed in warm spring and hot summer. Throughout the period, there was a continuing trend of increasing temperature. A higher value of the average monthly temperature by 0.9 С -- 1.5 С was observed in the insects-proof net house. The obtained results would be the basis for the development of risk analysis programs for the production of standard and certified fruit planting material in containers.
... Photo-selective nets with different shading characteristics can change the quantity and quality of solar radiation received by the plant [1,5,[8][9][10][11] and other climatic variables, such as relative humidity [6]. As a consequence, this leads to microclimates, often decreasing the crop's need for water [10,12], influencing the plant's light-regulated physiological responses including growth and development, yield and fruit quality, and even influencing the incidence of pollinators, pests and diseases [5][6][7]13]. ...
... This is considered an important aspect of photo-selective netting as it has been shown that radiation use efficiency increases when the diffuse component of incident radiation is enhanced under the nets [1,5,9,22,30] or by other means, such as reflective cloths at soil level [11]. Using nets with a higher shading effect of about 30%, Shahak et al. [8] reported that the scattered light-including all non-direct light-was higher in the pearl net, particularly scattering in the UV, compared to other coloured nets including the yellow net and the grey net, which were the least scattering. Here, the pearl net may have this higher scattered light effect. ...
... Horticulturae 2022, 8, 1062 ...
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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.
... According to the aforementioned, it is evident that the ability of nets to scatter radiation presents an important factor in light quantity manipulation. Diffuse light is a broad term and includes all non-direct light [16], and the capacity of each net to scatter radiation is also determined by its texture [18]. The light rays that pass through and are selectively filtered by the colored plastic threads come out of the threads in a fully diffused mode [18]. ...
... The light rays that pass through and are selectively filtered by the colored plastic threads come out of the threads in a fully diffused mode [18]. In a few studies, it was reported that the proportion of diffuse light was higher under photoselective nets than under a black net or in natural conditions [6,15,16]. Light scattering represents an important part of the technology of photoselective nets, since it improves the penetration of this spectrally modified light into the inner canopy, thus amplifying the photoselective effect [6,16,18]. In addition, radiation utilization efficiency increases when the diffuse component of direct radiation is increased in the shadow [35]. ...
... In a few studies, it was reported that the proportion of diffuse light was higher under photoselective nets than under a black net or in natural conditions [6,15,16]. Light scattering represents an important part of the technology of photoselective nets, since it improves the penetration of this spectrally modified light into the inner canopy, thus amplifying the photoselective effect [6,16,18]. In addition, radiation utilization efficiency increases when the diffuse component of direct radiation is increased in the shadow [35]. Therefore, plants cultivated under colored nets with a shading factor of 30% in reality "see" more light than those under black nets with the same shading factor [6]. Photoselective nets scatter less ultraviolet (UV) than photosynthetically active radiation due to the absorption of UV light by pigments embedded in their threads [15]. ...
Article
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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.
... Coloured nets can increase the content of scattered light for two or more times (Oren-Shamir et al. 2001). Scattered light has a better penetration possibility in dense canopies (or in the inner part of canopies), thus increasing the efficiency of light-dependent processes (Lakso & Musselman 1976;Shahak 2014;Shahak et al. 2004a). Moreover, due to light filtration ability (light quality modification) which is defined by pigments incorporated in plastic material (Shahak et al. 2016), they also promote specific plant physiological responses (Shahak 2014). ...
... The main reason for such findings is probably due to the shade avoidance mechanism, as proposed in other studies (Basile et al. 2014;Bastias 2011). Reduced red to far-red ratio, which occurs under the white and yellow net (Shahak et al. 2004a(Shahak et al. , 2004b, is according to Casal (2012) one of the main signals responsible for the shade avoidance mechanism. Shade avoidance mechanism symptoms include higher internode length and leaf elongation (Smith & Whitelam 1997), which was in this study recorded on peaches grown under the Y net. ...
... Such fruit colour changes are caused by nets light environment modification since according to Hamadziripi (2012) light intensity that reaches fruit skin has crucial effect on colour development. According to Westwood (1993), exposure of the peach fruit to direct light is necessary for the development of red colour, therefore enhancement of scattered light by photoselective nets (Oren-Shamir et al. 2001;Shahak et al. 2004aShahak et al. , 2004b cannot alleviate negative effects of shading on additional peach colour development. Hence, fruit additional colour parameters and indexes were highly reduced under the D net due to its high shading factor (indicated by smallest mesh size). ...
Article
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The effect of anti-insect photoselective yellow (mesh size of 2.4x4.8 mm) and Stop Drosophila Normal (mesh size of 0.90x1 mm) nets on the generative and vegetative traits of peach (cv. 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). Regarding fruit colouration application of nets significantly affected b* and C* background and L*, b*, C* and h° additional colour parameters. 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) was also under significant effect of netting. Since yellow net only slightly reduced peach fruit quality (compared to control) it can be recommended for application as an anti-insect net. However, Stop Drosophila Normal net more notably reduced quality parameters (especially additional fruit colour) and hence should be used only when other control strategies show to be ineffective.
... Alternatively, the use of shade nets is the most widely used approach, due to its low cost and simple operation [7]. Nonetheless, if the shade net type is not carefully selected and does not allow plants to maintain effective photosynthesis during the cooling process, shading will also affect plant growth [8] and reduce crop productivity. Recently, colored shade nets were introduced and have become widely adopted. ...
... Warren et al. [11] reported that the growth and yield of horticultural crops in growth facilities can be strongly dependent on light, and it is generally understood that shading affects grape quality [12]. The use of shading nets will reduce light intensity, such that the incorrect use of shading nets can have a negative impact on growth and production [8]. Hence, here we aimed to use colored shade nets to identify sunshade materials with a higher cooling effect, concomitant with high light-transmittance properties to achieve high-quality grape production. ...
... According to climate model predictions, the grape growing season will become warmer, while some cool climate regions are expected to become warm or hot regions by 2080 [13]. Climate warming has also led to rapid grape ripening and leaf aging [14]; however, shading can attenuate this problem, as colored shade nets show differential spectral transmittance and reflection properties [8]. Indeed, these nets are being increasingly and extensively adopted, and have shown to improve the microclimate [15], thereby providing an effective strategy for greenhouse crop production. ...
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High temperature causes premature grape leaf senescence, abnormal berry softening, and shortening of the fruiting period. Furthermore, the fruit quality and yield are severely affected. Here, the “Jumeigui” grape quality and leaf senescence were evaluated under shading; green, blue, black, and gray nets were used for shading, and their spectra were measured. At the same density, the shade-net color significantly affected cooling and shading efficiencies, with gray nets showing the best light transmission and cooling effect. Shading significantly alleviated abnormal heat-induced grape softness. The total soluble solids (TSS) content and grape coloration were affected under gray, blue, and green shade nets. Nonetheless, TSS exceeded 18% under gray, blue, and green nets, as required of first-class high-quality fruit. The peel color was not significantly affected under gray or blue shade nets, whereas unshaded grapes showed clear heat-stress damage, especially on the edges of unshaded bottom leaves, in which the net photosynthesis rate was significantly lower than that under shading, indicating that high light intensity and heat caused premature leaf senescence. Colored shade nets reduced greenhouse temperature and light intensity, thereby alleviating the premature senescence of grape plants. Grape quality under black shade nets was poor, whereas superior quality was achieved using gray or blue shade nets.
... Here, different colors of netting changed the transmitted spectra of light reaching the orchard canopy and fruit. Similar to the differences among treatments in this study, Shahak et al. [14] reported that blue netting had higher transmittance at 483 nm. The red netting used in this study had elevated transmittance at just under 600 nm, which was also reported in other studies [15,57,58]. ...
... Here, the pearl net had elevated scattered light spectra in the ranges 450-600 nm and 500-750 nm (Figure 3). Pearl net has already been reported to scatter more light, particularly in the UV region [14,15,[59][60][61]. Increased scattered light under pearl netting has been reported to improve light penetration into more shaded portions of the canopies [61]. ...
... Pearl netting had the highest PAR/UV ratios, and uncovered controls registered the lowest. These ratios were aligned to those reported previously in other regions or other crops [14,60,61]. The alteration of UV light under netting for the whole growing season was reported to affect the antioxidant activity and total polyphenols accumulation in kiwifruit at harvest [60]. ...
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High temperatures, wind, and excessive sunlight can negatively impact yield and fruit quality in semi-arid apple production regions. Netting was originally designed for hail protection, but it can modify the light spectrum and affect fruit quality. Here, pearl, blue, and red photoselective netting (≈20% shading factor) was installed in 2015 over a commercial "Cameron Select ® Honeycrisp" orchard. Our research objectives were to (1) describe the light quantity and quality under the colored nets compared to an uncovered control and (2) investigate the effect of Photoselective nets on "Honeycrisp" apple quality for two growing seasons. Light transmittance and scattering for each treatment were measured with a spectroradiometer, and samples for fruit quality analyses were collected at harvest. PAR (photosynthetic active radiation), UV, blue, red, and far-red light were lower underneath all netting treatments compared to an uncovered control. The scattered light was higher under the pearl net compared to other colors, while red and far-red light were lower under the blue net. For two consecutive years, trees grown under the photoselective nets intercepted more incoming light than the uncovered trees with no differences among the three colors. In both years, trees under red and blue nets had more sunburn-free (clean) apples than pearl and control. Red color development for fruit was lower when nets were used. Interestingly, bitter pit incidence was lower underneath red nets for both years. Other than red color development, "Honeycrisp" fruit quality was not appreciably affected by the use of netting. These results highlight the beneficial effect of nets in improving light quality in orchards and mitigating physiological disorders such as bitter pit in "Honeycrisp" apple.
... There is also the possibility of them reducing photoinhibition thereby increasing photosynthetic rates and productivity in areas where excess light intensity affects apple yields. Protective nets are also installed to protect crops from strong winds, birds, fruit bats and insects (Kotilainen et al., 2018;Shahak et al., 2004). Scientific literature has thus far focused primarily on the effects of nets on yield and fruit quality, especially in temperate climates where water is readily available (Do Amarante et al., 2011). ...
... This observation is contrary to results that have been reported in other studies. For example, Shahak et al. (2004) reported a 3-6 • C lower air temperature under nets compared to the control. A study on plum orchards by Malik (2020) in the same region (Western Cape Province, South Africa), using a similar 20% white flat shade net to the one used in this study, found a mean reduction in air temperature of ca. 1 • C under the net compared to the open orchard. ...
Article
Apple (Malus domestica Borkh.) producers are increasingly using nets to address climate and pest-related challenges. In the water-scarce Western Cape region of South Africa, all commercial apple orchards are irrigated. Based on limited information on tree water relations under protective nets, we hypothesised that significant water savings and improvements in crop water productivity could be achieved under nets. The lack of accurate quantitative information on water use under nets may perpetuate sub-optimal irrigation practices partly due to inaccurate crop coefficients. This study quantified tree transpiration (T) using the heat ratio sap flow method and orchard evapotranspiration (ET) using the soil water balance approach in mature irrigated ‘Rosy Glow’ apple orchards under fixed white net compared to an open (control) over two seasons. Differences in water use between treatments were analysed by comparing microclimates, plant water status, root zone soil moisture, and irrigation levels. Averaged over the two seasons, the nets reduced daily total solar radiation by ∼ 12%, wind speed by more than 36%, and reference evapotranspiration by ∼ 12%. Seasonal T was 11% lower under nets, while ET was only 4% lower. The nets reduced irrigation water requirement by 4%. Peak mid-season basal crop coefficients (Kcb) were 0.54±0.02 and 0.59±0.02 while there were no differences in the single crop coefficients (Kc = 1.07±0.04 and 1.13±0.06) for the nets and control treatments, respectively. Transpiration based crop water productivity (WP) was higher under nets (20.7 kg m⁻³) compared to 18.2 kg m ⁻³ in the open. There were no differences in the ET-based WP values (13.4 and 13.2 kg m⁻³) for the nets and control treatments, respectively. This study suggests that water saving benefits of fixed nets are smaller than expected when considering ET rates because of more active ground cover under nets. But there is merit in adjusting crop coefficients for irrigation scheduling under nets given the much lower transpiration.
... There is also the possibility of them reducing photoinhibition thereby increasing photosynthetic rates and productivity in areas where excess light intensity affects apple yields. Protective nets are also installed to protect crops from strong winds, birds, fruit bats and insects (Kotilainen et al., 2018;Shahak et al., 2004). Scientific literature has thus far focused primarily on the effects of nets on yield and fruit quality, especially in temperate climates where water is readily available (Do Amarante et al., 2011). ...
... This observation is contrary to results that have been reported in other studies. For example, Shahak et al. (2004) reported a 3-6 • C lower air temperature under nets compared to the control. A study on plum orchards by Malik (2020) in the same region (Western Cape Province, South Africa), using a similar 20% white flat shade net to the one used in this study, found a mean reduction in air temperature of ca. 1 • C under the net compared to the open orchard. ...
... The use of photo-selective nets in the greenhouse technology of crop production has expanded in the Mediterranean region since the early 2000s. Shahak et al. [4] were the first who concluded that colored shade nets, including red, yellow, blue, grey, and pearl nets, were more influential on horticultural production. Photoselective nets for plant covering refer to nets that can infiltrate intercepted solar radiation selectively and protect the plants. ...
... In contrast, the red and blue nets altered widely the spectral light distribution. Red net increased the light transmission in R and FR spectra (600-800 nm), while the blue net enhanced the proportion of B light (400-500 nm) and reduced the R light proportion (600-700 nm) [4,34]. The results showed that the application of colored nets had positive effects on the morphological and physiological traits of the strawberry so that the highest leaf number, shoot fresh and dry weight, chlorophyll content, carotenoid content, anthocyanins, and flavonoids were observed in the treatments of colored nets. ...
Article
BACKGROUND: The strawberry is an important commercial crop, the improvement of its yield and quality is an imperative task. OBJECTIVE: The present research aimed to study the effect of colored netting and foliar application of amino acids on the physiological characteristics of strawberries subjected to different irrigation intervals. METHODS: The study was carried out as a factorial experiment based on a randomized complete block design with three factors including colored net at 4 levels (no netting, green, red, and yellow netting), organic acids at 4 levels (control, humic acid, glutamine, and arginine), and three levels of irrigation intervals (2, 4, and 6 days) in the greenhouse of Lahijan Agricultural Research Station, Iran. RESULTS: The results showed that the highest leaf number, shoot weight, chlorophyll and carotenoid content were related to yellow netting. The highest fruit yield, anthocyanins, and flavonoids were observed in the treatments of no-netting, green netting, and red netting, respectively. Data for the effect of organic acids showed that the glutamine-treated plants exhibited the highest yield, the humic acid-treated plants displayed the highest anthocyanin and carotenoid content, and the arginine-treated plants demonstrated the highest vitamin C content. The irrigation interval of 6 days caused to the lowest leaf number, flower and fruit number, shoot weight, fruit yield, and carotenoid content. Data for the trilateral effect of ‘netting×organic acid×irrigation’ showed that the highest flower number and fruit yield were obtained from ‘green netting×glutamine×4 days’, the highest anthocyanin content was obtained from ‘green netting×humic acid×2 days’, and the highest chlorophyll content was obtained from ‘green netting×control×6 days’. The treatment of ‘yellow netting×control×2 days’ was related to the highest flavonoid content. CONCLUSIONS: The application of colored nets provides the strawberry with more optimal vegetative and reproductive growth.
... Different construction materials used for either netting or bagging can effectively change the spectrum of light that reaches the plant (Bast ıas and Corelli-Grappadelli, 2012). Shahak et al. (2004) found that netting peach trees with blue or red nets decreased the canopy temperature. Blue and white nets had no effect on fruit weight, whereas red netting increased fruit weight and both white and red nets increased vegetative growth. ...
... The purpose of this project was to determine if different-colored bags alter the temperature, RH, fruit quality, and known arthropod pest attraction for lowchill peach cultivars. This project tested the hypothesis that selective color filters within bags in the field can be used to affect the fruit quality of peach, such as increased anthocyanin for blue and red filters, decreased anthocyanin for black and green filters, and increased fruit size for red filters (Holopainen et al., 2018;Liu et al., 2015;Shahak et al., 2004;Wang and Folta, 2013). Parameters including temperature and RH inside the bag, insect attraction, and fruit quality parameters such as fresh weight, size, chlorophyll content, TSS, TA, pH, flesh firmness, anthocyanin concentration, peel color, flesh color, and nutrient concentration were analyzed to determine if bagging can provide growers with a practical means to improve fruit quality. ...
Article
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The use of paper or nylon bags (fruit bagging) to surround tree fruit during development provides protection from a variety of pest-disease complexes for peach without yield reduction and different-colored bags have the potential to improve fruit quality based on findings from other crops. An experiment was conducted in 2019 at two locations in central Florida on peach [ Prunus persica (L.) Batch] ‘TropicBeauty’ and ‘UFSun’ to analyze the impact of a commercially available white paper fruit bag combined with a photoselective insert. The insert reduced the amount of light outside the spectrum range of interest for blue (400–500 nm), green (500–600 nm), or red (>600 nm) wavebands, or decreased fluence rate with a neutral density black (>725 nm) insert. Relative to ambient, temperature inside all bagging treatments during the daytime hours was increased by 5.1 °C. During the same time, relative humidity was reduced by 10.1%, but calculations revealed that the water vapor pressure was elevated only for treatments that had a plastic colored (blue, green, or red) insert. An orthogonal contrast revealed that the elevated water vapor around the fruit in a colored bag increased the concentration of chlorophyll at harvest but had no effect on other quality parameters. Compared with unbagged fruit, red-bagged fruit were 1.8 times firmer and green-bagged fruit and had a lower peel chroma. White-bagged (without photoselective insert) fruit had similar nutrient concentrations for the peel, flesh, and pit when compared with unbagged fruit. When bags remained on the fruit until harvest, anthocyanin concentration in unbagged fruit peel was double the amount in white bags and 6-fold more than the bags with color inserts. Different-colored bagging treatments did not influence insect attraction or fruit quality parameters, such as fruit size, diameter, difference of absorbance (DA) index, total soluble solids (TSS), titratable acidity (TA), pH, peel lightness, peel hue, flesh lightness, flesh hue, or flesh chroma. Relative to full sun, the colored bag treatments allowed between 3.7% (black) and 17.4% (red) of the photosynthetically active radiation ( PAR ). Additional research is needed to determine if an increase in fluence rate at specific spectral wavelengths can affect the quality for peach grown in bags in the field.
... The less photoselective responses include improved external fruit quality (e.g., less sunburn and wind scars, smoother skin), reduced heat/chill stress, enhanced leaf photosynthetic rate and canopy activity, and better water use. These are probably related to reduced wind velocity, damping of extreme climatic fluctuations, and the overall more optimum microclimate induced by the netting (Shahak et al., 2004a). We describe below two major responses in more detail. ...
... The nets were applied 2-4 weeks after bloom (early-mid May), and moved aside early November each year. For more details see Shahak et al. (2004a). ...
Article
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Nets are frequently used to protect agricultural crops from excessive solar radiation, environmental hazards or pests. We have developed a new concept, by which the nets are designed to specifically filter sunlight, concomitant with providing the desired physical protection. A series of photoselective nets (Color Nets) was developed for outdoor use, each one absorbing different spectral bands, and at the same time increasing the relative proportion of scattered/diffused light. The spectral manipulation is aimed at specifically promoting physiological responses, while light scattering improves light penetration into the inner canopy. The relative enriching of the intercepted light with "good" parts of the spectrum, while reducing "bad" parts, may allow better utilization of the solar energy. Earlier studies of ornamental crops, traditionally grown under black shade nets, revealed differential responses to the photoselective shading. Ongoing studies of low-shading Color Nets in numerous fruit crops and climatic regions showed that nets of the same shading factor but different chromatic properties can differentially affect various attributes of tree performance, including production, fruit size and quality, and advancement or delay in the timing of harvest. The netting further ameliorates extreme climatic fluctuations, reduces heat/chill stresses, and improves the resulting canopy activity and water use. The results demonstrate the potency of photoselective netting for improving the agro-economical performance of horticultural crops, especially (but not only) in harsh climates and arid zones.
... In the last years, the use of the nets in stone fruit orchards was mainly evaluated as an anti-hail device [10,18] in relation to the qualitative and quantitative impact on fruit production [25][26][27][28][29][30][31][32] and/or in relation to plant physiology [26,31]. This study deals with the application of the net in a multidisciplinary approach focusing on pest and disease management and on qualitative-quantitative aspects in fruit production. ...
... Insect wounds could represent one of the main entrances for postharvest rots [46]. Several authors already reported the positive effects of photoselective nets on stone fruit quality [25,27,30]. In our trial, significant differences between the treatments (N, C, I) were observed at harvest in 2017 but not in 2016 [14]. ...
Article
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Over the past few years, there has been an increasing interest in the development of alternative pest control strategies to reduce environmental impact. In this contest, exclusion nets have been evaluated as a sustainable alternative to pesticides. In this study, the use of a photoselective exclusion net was investigated in semi-field conditions as a potential strategy to protect nectarine orchards from different pests (i.e., fruit moths, Halyomorpha halys and Drosophila suzukii) in NW Italy. The presence and abundance of pest populations inside and outside the net, as well as the damage they caused on fruits, were evaluated. Moreover, any possible effects of the net on beneficial arthropods, postharvest rots and fruit quality and nutraceutical parameters were considered. The exclusion net significantly reduced pest populations. At harvest, fruit damage caused by Grapholita molesta and H. halys in netted plots was reduced up to 90% and to 78%, respectively, compared with insecticide-treated plots. The exclusion net allowed the production of healthier fruits with a strong reduction of insecticide treatments (up to seven less) and of their related costs without any negative impact on postharvest rots, neither fruit quality nor nutraceutical properties.
... Considering the different types of colored nets, black nets have been demonstrated to improve WUE and fruit quality in different fruit and vegetable crops, while pearl and yellow nets improved antioxidant activity, fruit yield and quality [13,15]. Likewise, the use of red nets induced greater fruit set in peach and apple, relative to other color nets and to un-netted controls [24], while a rapid development of the root system of banana plug transplants during hardening has been associated to the use of red net-covered plants when compared to the commercial black nets [25]. In 'Valencia' orange trees cultivated under top red netting, productivity was improved, as determined by fruit number, fruit size and overall yield [26]. ...
... In fact, our study demonstrated that shading plants with red nets improved leaf water and osmotic potentials as well as relative water content, especially under salinity conditions (Table 1). This can be explained by a higher decoupling of the shaded plants from the atmosphere, particularly under high evaporative demand [12], as shown in apple and peach orchards grown with protective netting, which improved stem water potential with respect to non-shaded orchards [24]. ...
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The actual climate crisis scenario is aggravating the abiotic stress episodes that crop plants have to face. Salinity is one of the most important abiotic stresses directly impairing plant growth and productivity. Several strategies have been developed to minimize the negative effects of salinity in agricultural industry, mainly at the plant level, while management strategies, such us the control of microclimate conditions and light quality over plant canopy, have also been used. Indeed, shading plants with photoselective nets has been considered an efficient management strategy to modulate solar radiation to improve crop productivity. The aim of this work was to gain insights about the physiological factors underlying the salinity-alleviating effect of using red shading nets. For that, pepper plants (Capsicum annuum L.) were grown under control (0 mM NaCl) and moderate salinity (35 mM NaCl) conditions, with half of the plants covered with a red net (30% shading). The shoot growth impairment provoked by salinity was in part minimized by shading plants with red nets, which can be explained by their higher capacity to exclude Na + , control of K + homeostasis and regulation of hormonal balance. Indeed, the concentrations of the most active cytokinin in pepper, trans-zeatin, as well as its metabolic precursor, zeatin riboside, increased in shaded plants, associated to shoot growth recovery and photosynthetic rate maintenance under salinity. Furthermore, the stress-related hormone abscisic acid (ABA) increased with salinity but in a lower extend in the plants shaded with red nets, suggesting a fine tune of stomata opening by ABA which, in crosstalk with salicylic acid increment, improved plant water relations. Likewise, the concentrations of gibberellins and the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid, also changed during salinity stress in shaded plants but those changes were uncoupled of growth responses as indicated by the principal component analysis and thus they seem to play a minor role. Our data demonstrate that shading pepper plants with red nets is an efficient management strategy to modulate microclimate conditions at crop level thus controlling the ion homeostasis and hormonal balance of the plant to cope with salinity stress. This is especially important due to the actual and expected changes of the global climatic conditions.
... Use of the photo-selective color shade nets to reduce radiation and temperature is a management system that is gaining popularity in a broad range of plants and could be helpful in reducing environmental hazards experienced by blueberries in farm fields of production. Research has been conducted to evaluate the reaction of ornamental plants (Schiappacasse et al., 2007;Ovadia et al., 2009;Saifuddin et al., 2010), vegetables (Rylski and Spigelman, 1986a, b;Lopez et al., 2007) and fruit crops (Stampar et al., 2001;Shahak et al., 2004;Cohen et al., 2005;Jakopic et al., 2007;Dufault and Ward, 2009) shade, that often minimize crop growth and development (Soto-Pinto et al., 2000;Zhang et al., 2004;Stephan et al., 2008. Shade nets are used cover crops to lower the heat stress (Elad et al., 2007;Retamales et al., 2008;Shahak et al., 2004); furthermore, in closed net (shade) houses, daytime temperatures are usually higher than outside (Pe'rez et al., 2006;Stamps, 1994) and might be lower at night, at least during radiation freezes (Stamps, 1994). ...
... Research has been conducted to evaluate the reaction of ornamental plants (Schiappacasse et al., 2007;Ovadia et al., 2009;Saifuddin et al., 2010), vegetables (Rylski and Spigelman, 1986a, b;Lopez et al., 2007) and fruit crops (Stampar et al., 2001;Shahak et al., 2004;Cohen et al., 2005;Jakopic et al., 2007;Dufault and Ward, 2009) shade, that often minimize crop growth and development (Soto-Pinto et al., 2000;Zhang et al., 2004;Stephan et al., 2008. Shade nets are used cover crops to lower the heat stress (Elad et al., 2007;Retamales et al., 2008;Shahak et al., 2004); furthermore, in closed net (shade) houses, daytime temperatures are usually higher than outside (Pe'rez et al., 2006;Stamps, 1994) and might be lower at night, at least during radiation freezes (Stamps, 1994). ...
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Little research has been done on blueberry under shade nets in northeastern china. We used two color nets black and green with three different level of shade 30%, 50%, 70% nominal shade. We used two variety of hight bush blueberry pulan 9 & northland. Leaf size (width, length) were measured after when all leaves matured, internodes distance, leaf size, fruit yield, and harvest delay were recorded, In early September plant height, east and west crown, number of basal branches, and their height were assessed. We observed that internodes distance decrease with an increase of shade black 50% pulan 9& black 70 % northland showed lowest record. Leaf size (width/length) increased with an increase of shade level, black 70% of both variety showed lowest record as compared to control. fruit yield decreased with an increase of shade level in both variety, black 70 % showed the lowest weight with 1.1kg of pulan 9 and 1.8kg northland as contrast to open treatment 3.7kg and 5.8kg. Shading high bush blueberry generally delays fruit harvesting time. this experiment showed green 50%,70% of pulan 9 was ready to pick up (3,7 days) after control treatment & northland green 50%,70%(4,8 days) .while black 30%,50%,70% of pulan 9 was ready to pick up (5,11,14 days) after control treatment other hand northland black 30%,50%,70% was (6,12,15 days).the result showed increase of shade level has negative impact on growth plant bluerry specially 50% and 70% .
... In the last decades, advances in netting systems have focused on the development of photoselective materials with the capacity to transmit selectively the solar radiation to promote positive physiological responses and improve the yield and fruit quality through the addition of specific colors during the manufacture of the nets [56]. In the first studies carried out on apple trees, it was verified that the use of the photo-selective blue net allowed to increase in fruit growth in comparison with the red net, and through the promotion of greater photosynthesis and partition of assimilates toward the fruit [14]. ...
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Apple crop is more and more cultivated under protective netting systems. Depending on the location and sunlight intensity, apple orchards can benefit from these installations, as they will be protected against extreme weather events. Depending on the technical features of the thread, the nets will be hail-proof, wind-proof, or rain-proof, while having different shading percentages. Modern fruit production faces high pressure also related to biotic stressors; thus, modern protective nets are designed to aid pest management. These protective systems become interesting, as they will induce changes in the orchards’ microenvironment, with consequences on crop physiology. Netting mainly reduces incoming solar radiation and wind speed, altering the heat balance. Leaf gas exchanges and water relations can be positively influenced by netting in apple cultivation areas with extreme solar radiation, high temperatures, and low water availability. These considerations are important, especially if the final yield and quality are not compromised by shading. These protective systems can allow higher sustainability of apple production, lowering resource use, along with crop protection.
... introduction in early 2000 compared with the most largely used black and neutral nets . Color nets represent a new agro-technological concept that combines physical protection with differential filtration of solar radiation (Bastıás et al., 2012;Oren-Shamir et al., 2001;Shahak et al., 2004a). Photo-selective netting has gained attention from both the academic world and the horticultural industry Shahak, 2008;Shahak et al., 2016). ...
Article
Photo-selective anti-hail plastic nets have spread in southern Europe for multifunctional purposes. These nets can influence the spectral composition of natural light and modify the responses of plants to extreme values in the summer. High-density polyethylene (HDPE) nets have different shading factors with specific differences in light spectra. The present work studied the effects of photo-selective anti-hail nets on pomegranate trees (Punica granatum L.) ‘Akko’ in southern Italy (Montalbano Jonico, MT). The two-year-old ‘Akko’ plants are grown with a vase-shaped training system. Photo-selective nets: yellow, red, pearl, fluo; and grilux (gray) compared with a not covered control have been installed from fruit set (end of July) until complete fruit maturation on an arched structure. Hail nets affect several environmental factors: light, airflow and temperature. The installation of all the nets late in the summer season did not affect the production, but it preserved fruit quality by reducing hail damage and sunburn, controlling soil temperature, wind speed and hail damage, and shadowing from excess light. It was possible to observe a generally positive performance of the photo-selective nets (yellow, fluo, red, pearl) on photosynthesis and an anticipation in leaf fall limited only to grilux, red and fluo nets.
... Essential oil content and composition in Ocimum spp depended on edaphic and climatic conditions of the location, growing season and maturity stages of the plant (Laskar and Majumdar, 1988). Among the environmental factors that have an impact on plant growth, development and yield, both quality and quantity of light transmitted to canopy play a vital function (Shahak et al., 2004). As per Milenkovic et al. (2019) accumulation of essential oil was more in shaded plants compared to unshaded condition. ...
... The apple growing season in Washington State, USA, is characterized by high light intensities, ambient temperatures, and occasional hailstorms, all of which negatively impact both the tree and fruit (Kalcsits et al., 2017). Protective nets are increasingly being utilized in apple production in Washington State and other semi-arid apple production regions such as Israel, Chile, Australia, and South Africa that experience similar climatic conditions (Mupambi et al., 2018a;Shahak et al., 2004). The apple cultivar 'Granny Smith' is sensitive to sunburn development (Racsko et al., 2011). ...
Article
Light is essential for flower bud formation in apple trees and is positively correlated with return bloom. Worldwide, apple trees are increasingly being grown under protective netting to prevent fruit sunburn and protect trees from hail damage. However, return bloom can be negatively affected under protective nets from the resulting low light conditions. Reflective groundcovers have been previously reported to increase the amount of reflected and diffuse photosynthetically active radiation (PAR), particularly in the lower and interior tree canopy. Our objective was to test whether reflective groundcover can improve light penetration into the tree canopy and thereby improve return bloom and yield under protective netting. The trial was conducted in 2018 and 2019 on a ‘Granny Smith’ orchard on M29 rootstock; trees were trained on 4-wire tall spindle trellis and spaced 0.9×3.6 m. The trial was conducted under a 17% white neutral protective net; the treatments were protective netting with a reflective groundcover and protective netting without reflective groundcover (grass control). The trial design was a randomized complete block design with four replications per treatment. The amount of reflected and diffuse photosynthetically active radiation (PAR) was measured 1.5 m above the ground during the growing season. Yield, and fruit quality was assessed at harvest. Return bloom was assessed in 2019 by counting the number of flower clusters from two trees in each treatment replication. Reflective groundcover significantly increased the amount of reflected and diffuse PAR in the center of the drive row and the tree canopy compared to the grass control. Reflective groundcover significantly increased return bloom compared to the control. Although not statistically different, yield was numerically higher (22.6% greater) when reflective groundcover was used compared to the control. There was no difference in total soluble solids and titratable acidity between the reflective groundcover and the control. In conclusion, using reflective fabrics under protective netting could be a potential solution to improve return bloom and yield in apple production.
... Studies in apple have differed widely regarding changes in photosynthetic rate under hail netting (Bastías et al., 2012;Ebert and Casierra, 2000;Iglesias and Alegre, 2006;Mupambi et al., 2018;Romo-Chacon et al., 2007;Shahak et al., 2004). Given that the results of our study have shown significant decreases in mean fruit weight and SSC, but higher shoot length under increasing shade factor, heavy shading may have caused a shift in carbohydrate partitioning that increased allocation to vegetative organs compared to fruit. ...
Article
The recent introduction of new blush pear cultivars has gained increasing consumer interest. The purpose of this study was to investigate the influence of different protective netting shade factors on environmental conditions, fruit growth, vegetative growth, blush colour, blush coverage, fruit quality and yield of the Australian blush pear cultivar 'ANP-0118′. Three nets of varying shade factors (30, 50 and 80%) were assigned to experimental plots, in addition to unnetted plots. All netting used was black in colour. Photosynthetically active radiation (PAR) penetration near sample fruit was assessed and blush colour parameters, fruit diameter and shoot length were monitored weekly. Whole trees were harvested and measured for fruit weight and blush coverage with a fruit grader. Fruit was assessed manually for flesh firmness and soluble solids concentration. Fruit and shoot growth were negatively and positively affected by shade factor, respectively. Overall, increasing shade factor was detrimental to fruit size, blush redness, blush coverage and soluble solids concentration but did not affect flesh firmness. Unnetted fruit achieved highest PAR exposure, and consequently expressed highest blush redness and blush coverage. Yield was similar in unnetted and 30% shade factor plots. The results of this study suggest that the use of shading nets should be limited in order to avoid unfavourable effects on key quality traits in Australian blush pears, yet further exploration into the influence of lower shade factor nets in combination with reflective mulch and biostimulants would be beneficial to the industry.
... Photo-selective nets (PSNs) improve crop production since combining physical protection of the orchards and differential filtration of solar radiation can promote certain physiological responses in focal plants (Shahak et al., 2004a;Shahak et al., 2004b). PSNs can reduce the light quantity reaching the crop and transform direct light into diffused light, by incorporating chromatic or light-dispersive additives into the plastic material (Shahak et al., 2008a;Antignus, 2014). ...
Article
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.
... Three-by-three meter pieces of the transparent, pearl, and red nets were mounted three meters above the flat roof of a four-story building at the Volcani Institute, Israel, allowing for unobstructed testing. The spectra of the solar radiation in the range of 300 to 1000 nm both under and outside the nets were measured by a LiCor LI-1800 spectroradiometer employing a light diffuser of 4 cm diameter above the 300 µm fiber optics, as described [24]. In brief, the light diffuser was oriented parallel to the sunbeam and an opaque disc was held 40-50 cm above the sensor to measure the scattered light. ...
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Fruit tree production is challenged by climate change, which is characterized by heatwaves, 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.
... Lakso and Goffinet (2013) noted how, about 3-4 weeks after bloom, the tree urges vegetative growth, to the detriment of the productive yield (Grappadelli et al., 1994). In Table 2, year 2017 showed no significant differences, regardless of LEs, known to impact on vegetative growth (Shahak et al., 2004a(Shahak et al., , 2004bMupambi et al., 2018). In 2019, the situation was completely different, and LEs seemed to influence vegetative growth. ...
Article
The objective of this 2-year study (2017, 2019) was to evaluate the influence of photoselective nets on apple fruit growth, focusing on the initial fruit growth stages of “Pink Lady”. Trees were subjected to four photoselective nets (Blue, Red, White and Yellow) and a standard black one (serving as Control), resulting in 5 light environments (LE), all shading at 20%. From 20 to 90 DAFB, 32 fruit and extension shoots, for each LE, were measured for a total of 11 times during the season. For each LE, fruit gauges were also installed to monitor fruit daily growth parameters, from 50 to 90 DAFB. At harvest, all fruit from each light environment were weighed and quality parameters were measured on 40 fruit per treatment. For each year, correlations were made to test the influence of LEs on final fruit weight and quality, and the impact that extension shoot growth had on fruit growth. In both years, white and control nets led to the production of fruits with higher weight compared to the other treatments (blue, red and yellow nets). In 2019, LEs did not appear to influence the relationship between shoot and fruit growth, probably due to the higher crop load and the massive pruning carried out the previous year. The higher vegetative outburst in this year might have unbalanced resources towards the shoots, than towards the fruit. Results show how weather and orchard management heavily influenced the trees responses. Yet, the consistent findings of final fruit weight, for both years, indicate that different wavelengths influence fruit and shoot behavior, even at early phenological stages. Hence, growers searching for bigger fruit should refer to white and black nets. Further studies approaching this technology can help improve apple production management and knowledge of the use of photoselective nets.
... Another important experimental aspect for interpreting the study results is related to the fact that shading was applied from full canopy development until harvest during the three years. This may have prevented multiple effects of shading on canopy development, leaf morphology, and fruit set, as found in other studies [24][25][26][27][28]. It is therefore likely that in this study, the consequences of shading on fruit industry relevant traits (yield and quality) were mainly due to tree water relations and leaf gas exchanges experienced during the period when the nets where present in the orchard. ...
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The sustainability of reducing light in apple orchards under well-watered (ww) and water stress (ws) conditions was evaluated for water relations, plant gas exchanges, fruit growth, yield determinants, and fruit quality over three years. A black (B) 28% shading net was compared with two different 50% shading nets: red (R) and white (W). Each net was combined with two irrigation regimes (ww and ws) based on plant water status. Under ww and ws conditions, increasing shade from 28% to 50% was not detrimental for plant gas exchanges, yield, or quality over three years. Higher shade improved plant water status regardless of irrigation regime. Higher shading could be considered sustainable in apple orchards over several seasons. Fruit quality was more sensitive to plant water status than to light reduction. ws increased fruit soluble solid content and relative dry matter, regardless of shading, and this was positively reflected in consumer’s preference. When water availability is limited, increasing shading to 50% can help save water and maintain high-quality yields associated with water stress. Given the likely reductions of water availability in agriculture, growers and consultants may consider shading apple orchards as a sustainable and safe horticultural technique to save water.
... Contrary to more common hail nets, photo-selective nets are usually deployed to decrease light intensity and to alter the spectrum, to buffer extreme temperatures and increase RH (Shahak et al., 2004(Shahak et al., , 2008Elad et al., 2007;Wachsmann et al., 2014;Ilić et al., 2015). In warm temperate production regions of South Africa, climate warming is affecting accumulation of chill units and RH, eventually reaching a critical threshold for temperate deciduous fruit and nut trees (Midgley and Lötze, 2011;Midgley et al., 2016). ...
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Hazelnut (Corylus avellana L.) is one of the most appreciated nut crops, which is motivating the cultivation outside its historical production areas. Despite that, there is still limited knowledge about the floral biology of the species and its developmental fruiting stages under different environments. Adverse climatic conditions can threaten the pollination process and fruit development. In South Africa, the deciduous fruit industry identified the net shading as a tool to mitigate the effects of unfavourable abiotic events. The objective of this work was to investigate the effects of photo-selective nets on the pollination process and nut development of C. avellana. Mature hazelnut trees were maintained under netting and compared with the ones in open field. Microscopic examination of female flower and developing nuts were conducted in order to observe the pollen tube growth and the pattern of disodium fluorescein transport into the funiculus and ovule. The results showed differences in pollen tubes growth and timing between the treatments. Generally, trees under nets showed higher rate in pollen tubes developing and reaching the base of the style. On the contrary, the tests carried out in open field showed a higher ratio of pollen tubes arrested in the style. The results also indicated differences in ovules abortion. Developing fruits that showed an interruption point at the funicle level or at junction point of the ovule were classified as aborting fruits (blank nuts at harvest time). A higher rate of abortion was detected in open field compared to the plants under netting. In conclusion, the shade nets influenced the pollen tube growth and the nut development, principally due to micro-climate modification. Therefore, further investigations are needed to analyse the influence of light spectra and to determine the sustainability of photo-selective nets over several years.
... As telas de sombreamento no interior do ambiente protegido podem proporcionar condição microclimática apropriada para o desenvolvimento da cultura, reduzindo os efeitos nocivos da alta taxa de incidência da radiação solar e da temperatura sobre a planta (Shahak et al., 2004). Essas telas de coberturas, devem apresentar boa ventilação para possibilitar o seu uso no verão, além de diminuir a temperatura e evitar danos no sistema radicular e foliar (Anglés, 2001). ...
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A abobrinha italiana está entre as dez hortaliças de maior valor econômico e produção nacional. Entretanto,estudos de cultivares e seucultivo sobsombreamento,são escassos. Sendo assim, estapesquisa foi desenvolvida com o objetivodeavaliar o comportamento produtivode cultivares de abobrinha a pleno sol e sombreada. Utilizou-se o delineamento deblocos, com quatro repetições e os tratamentosobedeceram aoesquema fatorial 5x2sendo cincocultivares de abobrinha(“Anita F1, Brenda F1, Irit F1,Corona F1 e Caserta”)edoissistemasde cultivos(a pleno sol esombreamentocom tela preta), respectivamente. O ambiente de cultivo influenciou a produção de abobrinhas italianas. Frutos com maior diâmetro foram produzidos pela cultivar Brenda F1. As cultivares Anita F1 e Corona F1 produziram frutos com maior comprimento e, Brenda F1 e Corona F1 frutos com maior massa. O cultivo a pleno sol proporcionou maior número de frutospor planta, com exceção da cultivar Irit F1 que apresentou maior número de frutos no cultivo sombreado. O cultivo a pleno sol apresentou maior produtividade e produçãocomercial quando comparado com o cultivo sombreado. A cultivar Brenda F1 cultivada a pleno sol apresentou maior produtividade e produçãocomercial. As cultivares Corona F1 e Irit F1 apresentaram maiores produtividade e produçãocomercialquando cultivada com sombreamento. O cultivo de abobrinha italiana sombreadanas condições daregião Nordeste é viável, pois minimizaosefeitos negativos do ambientede cultivo, evitando-se, principalmentefrutos queimadospelo sol, assegurandosuaqualidadevisual, nutricional e sensorial. Palavras-chave:Brenda F1; Caserta;Cucurbita pepo;IritF1;Cultivares; Sistemas de cultivo.
... SPRING 2020 product: a complete exclusion PN system. Although the Drape Net is advertised for hail and solar radiation protection, complete exclusion netting systems have proved to be effective barriers against bird damage, fruit bats and insects (Arthurs et al., 2013;Shahak et al., 2004), and are increasingly employed in organic production systems (Granatstein et al., 2016). Our studies in 2018 were conducted in two research blocks at the Hudson Valley Research Laboratory to evaluate both sunburn and insect exclusion: In sunburn trials we assessed the effect of season long applications of Surround® WP, Purshade®, ScreenDuo® with the Drape Net system installed using two colors: white and black compared on sunburn control and on fruit quality. ...
Article
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Protected culture of crops, specifically of tree fruit, has been studied since the mid- 20th century, gaining global acceptance over the past decade to provide shade, reduced fruit injury due to sunburn and reduced injury from invertebrate and vertebrate feeding and reduced pesticide use through the use of complete netted exclusion.
... As a result, all the applications gave positive effects compared to the control for the physiological parameters. Previous studies conducted with kaolin to decrease the temperatures on fruits and leaves were found to have similar results to our results (Beppu and Kataoka, 2000;Glenn et al., 2002;Shahak et al., 2004;Kudela and Krejzar, 2005;Gindaba and Wand, 2007;Yazici and Kaynak, 2007;Imrak, 2010;Sotelo-Cuitiva et al., 2011). They have also found that kaolin application decreased the temperatures on the surface of fruits and leaves and had positive effects on the photosynthesis speed and stomatal conductance. ...
... In tree crops, stomatal conductance is known to be enhanced under blue light, with likely increases in transpiration and whole tree water use (Bastías, 2011a,b;Lopez et al., 2018). Similarly, shoot growth and length internodes are affected (Iglesias and Alegre, 2006;Bastías et al., 2012;Basile et al., 2012) with possible shifts in source-sink relations (Shahak et al., 2004;Bastías et al., 2012). Potential impacts on yield and final fruit quality have also been assessed (Lopez et al., 2018;Bosančić et al., 2018;Mupambi et al., 2018;Manja and Aoun, 2019). ...
... There are several studies demonstrating that under red enriched wavelengths plants have higher growth rates when compared to blue enriched and normal wavelengths (Oren-Shamir et al., 2001). Shahak et al. (2004) reported that, compared to the black net, red significantly stimulated vegetative growth and the blue caused dwarfism in plants. Shahak et al. (2002) also observed a delay in the plant growth under blue-green wavelengths when cultivating Aspidistra elatior, Aralia sp., Asparagus officinalis and Monstera deliciosa. ...
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The practice of using different photo-selective nets, associated with the technique of fertigation, represents a new agrotechnological concept that aims to promote specific physiological responses for growth and production, which are regulated by light. The aims of the study were to evaluate the effect of photo-selective nets and potassium concentrations in the fertigation solution on the horticultural performance of Costus lasius. The study was conducted at the Universidade de São Paulo, ESALQ, Piracicaba, SP, Brazil. Three experiments were carried out separately to evaluate five potassium concentrations in the fertigation solution (40, 80, 120, 160 and 200 mg L-1) under three colours of photo-selective nets (red, blue and black) in a randomized block design, with five repetitions. The variables plant height and numbers of leaves, stems and flower buds were evaluated. The data were submitted to the joint analysis of experiments. The association between the K+ concentration of 200 mg L-1 and the black photo-selective net results in higher stem and inflorescence production.
... In order to mitigate the effects of shading caused by anti-hail netting, photoselective anti-hail nets appeared as an alternative to increase the efficiency of light dependent processes (Shahak, 2014) through the manipulation of both quantity and quality of the incident radiation over tree's canopy portions (Rajapakse and Shahak, 2007;Basile et al., 2012). In this sense, a wide number of chromatic additives, e.g., dispersive elements and light reflectors, are incorporated into the materials during its manufacture (Shahak et al., 2008;Mupambi et al., 2018) aiming to provide differentiated absorption in the ultraviolet (UV) spectral regions, blue, green, yellow, red, far red, or near-infrared, as well as transform direct light into diffuse light (Shahak et al., 2004;Shahak, 2014). The traditional black and white nets, as well as photoselectives nets, efficiency in the orchards protection and their possible effects on fruit quality were also addressed in several studies. ...
... Previous studies on evergreen shrubs showed variation in the nutrient and foliar pigment contents (Katahata et al., 2007;Muller et al., 2011) as a response to variable environmental conditions. Other studies determined several plant responses at different shading levels and with the use of different shade-mesh colors in fruit tree production (Stampar et al., 2001;Shahak et al., 2004aShahak et al., , 2004bCohen et al., 2005;Jakopic et al., 2007;Dufault and Ward, 2009), through the modification of radiation and temperature levels. ...
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Berberis microphylla G. Forst. commonly named calafate, is a Patagonian shrub that grows in humid areas of the steppe, coastal thickets, edges and gaps of Nothofagus forests or along streams and rivers, with small purple berries. The objective of this study was to evaluate the changes in leaf nutrient (carbon, nitrogen, carbon:nitrogen, phosphorus and potassium) and pigment contents (chlorophyll a and b, chlorophyll a:b ratio and carotenoids) of B. microphylla plants growing under different irradiances (low = 24%, medium = 57%, and high = 100% of the natural irradiance) and fertilization levels (0 = 0.00 g, 1 = 3.36 g, and 2 = 6.72 g per plant) during two growing seasons (2008-2009, 2009-2010). Also, we explored the relationships of these variables with anthocyanin, as well as with total phenol fruit contents. The fertilization has been highlighted, particularly in the content of foliar nutrients, where nitrogen, phosphorus and potassium contents were highest with fertilization level 2 (2.0%, 0.1%, and 0.6%, respectively), while carbon:nitrogen ratio (37.5) was maximum on fertilization level 0. Irradiance has greatly affected the content of foliar pigments. Thus, chlorophyll a, b, and carotenoids were highest under low irradiance (0.4, 0.1 and 0.2 mmol/m2, respectively), while chlorophyll a:b ratio was maximum under medium and high irradiance conditions (3.1). In addition, the quantity of fruit secondary metabolite (anthocyanin and phenol) could be estimated using carbon and potassium leaf contents and chlorophyll a and b contents. On the other hand, the annual climatic variability between 2008-2009 and 2009-2010 mainly affected the variables on nutrient and pigment contents, likely evidencing the influence of two distinct climate periods, El Niño/La Niña phenomena, respectively. The changes observed in the leaf nutrient and pigment contents of B. microphylla could be related to the acclimation capacity of B. microphylla shrubs to changes in environmental conditions via arrangements in leaf composition.
... In tree crops, stomatal conductance is known to be enhanced under blue light, with likely increases in transpiration and whole tree water use (Bastías, 2011a,b;Lopez et al., 2018). Similarly, shoot growth and length internodes are affected (Iglesias and Alegre, 2006;Bastías et al., 2012;Basile et al., 2012) with possible shifts in source-sink relations (Shahak et al., 2004;Bastías et al., 2012). Potential impacts on yield and final fruit quality have also been assessed (Lopez et al., 2018;Bosančić et al., 2018;Mupambi et al., 2018;Manja and Aoun, 2019). ...
... Large mesh size would certainly allow the easy access of most small insects, as their intended use is protection again excess radiation, weather and birds and bats. Coloured shade netting has been under evaluation as a promoter of plant growth and yield (Shahak et al., 2004;Rajapakse and Shahak, 2007). In conjunction with the studies on plants, entomologists have started looking at the effects of the coloured shade nets on insect-pest populations. ...
... Devido à variedade de malhas de sombreamento existente, a escolha do tipo de malha ideal para cada cultura, de acordo com seu percentual de sombreamento e propriedades físicas de transmissão da luz sobre elas incidente, é fundamental para garantir um microclima propício ao desenvolvimento do vegetal e desta forma, garantir o sucesso da produção (SEABRA JÚNIOR et al., 2012;SHAHAK et al., 2004). Silva et al. (2016a) relatam que o sombreamento com telas de diferentes colorações modificam a composição química de frutos de diferentes espécies de fisális quanto a presença de antocianinas, fenólicos totais, ação antioxidante, dentre outros componentes. ...
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As plantas são diretamente afetadas por fatores ambientais tais como, estresse hídrico, temperatura, radiação, dentre outros. Estes fatores afetam não só os órgãos vegetativos, mas também estruturas reprodutivas, podendo acarretar danos à plantas agronomicamente exploradas. Physalis peruviana L. é uma espécie de interesse comercial pertencente à família Solanaceae, cultivado preferencialmente em ambiente sombreado, que ainda apresenta cultivo restrito a pequenas áreas no Brasil. Diante da necessidade de sombreamento apresentado pela cultura o presente trabalho objetivou caracterizar o grão de pólen da espécie para futuras aplicações em programas de melhoramento genético e verificar a influência de malhas fotoconversoras utilizadas no sombreamento sobre a morfologia externa dos grãos de pólen desta espécie. O trabalho foi desenvolvido na Universidade Federal de Lavras, onde três repetições de duas plantas foram cultivadas a pleno sol e sob malhas fotoconversoras nas colorações branca, azul, vermelha e preta. O pólen de flores em antese foi coletado, processado e fotografado em microscopia eletrônica de varredura (MEV). O diâmetro polar, diâmetro equatorial e área do pólen foram medidos em dez grãos de pólen. Os resultados demonstraram que grãos de pólen de P. peruviana são isopoloares, radiais, de formato prolato-esferoidal e tamanho mediano. Também verificou-se aumento da área do grão de pólen quando cultivado em sombreamento com malha fotoconversora branca e a pleno sol.
... Researchers have argued that better performance of yellow shade nets than red nets in stimulating vegetative growth is likely to relate to the stimulating effect of artificial green light supplementation (Kim et al., 2004;Oren-Shamir et al., 2003). A study on peach (Prunus persica "Hermosa") showed the increased growth under yellow and red nets (Shahak et al., 2004a(Shahak et al., , 2004b.In our study too, the highest growth rate was observed in plants treated with yellow nets.A study on the effect of colored shade nets (20-30% shading in PAR) on several cultivars of table grape in four different regions indicated that yellow nets increased plant size significantly in all cases (Shahak, Ratner et al., 2008). ...
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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 physiological traits of marigold and violet plants, a split-plot experiment was carried out. The trial was done with two factors including colored shade net at four levels (no net, green, yellow and red net) and two plant species (marigold and violet). The results showed that yellow shade net increased the vegetative growth of the plants. However, the highest leaf area was related to the red shade net. Chlorophyll content, Brix°, and carotenoid content were significantly higher in plants grown under the yellow net. The highest peroxidase was obtained from green and red shade nets. The plants grown under the green shade net had higher anthocyanin and antioxidant activities than other shade nets. The interaction of ‘shade net × plant species’ showed that the highest root and flower fresh weights were related to ‘yellow net × marigold’, the highest plant growth rate, total chlorophyll, and carotenoid contents was related to ‘yellow net × violet’. The results revealed that yellow shade nets outperformed the other nets in improving plant growth.
... In one study [31], the authors reported that while netting did not affect air temperature, it greatly reduced fruit surface temperature during full sun and hot periods, because of the light scattering effects of the nets [35]. Scattering reduces direct exposure to radiation but improves light penetration into the plant canopy, thus increasing photosynthesis efficiency [36,37]. The light scattering effects of netting can be significant: for white antihail nets, a scattered/total light ratio of 23% was reported in the PAR range of 400 to 700 nm in a study [35]. ...
Article
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Exclusion nets have been used successfully to protect fruit from insect pests of apples under various conditions, but the effect of each particular netting system on the plant itself has rarely been investigated. In this study, a complete exclusion system—in which the soil is also excluded—was used to grow ‘Honeycrisp’ apples for six years in southern Quebec, Canada. Abiotic conditions, as well as plant photosynthesis and fruit quality characteristics (colour, firmness, size, sugar content, number of seeds, ripeness and skin integrity) and yield were estimated yearly and compared in netted (either with or without a rainproof top) and unnetted row units. Although annual variations were high and results showed little or no difference between netted and unnetted rows for all measured variables, with the following exceptions; colour (increased red surface on fruits from unnetted rows some years), size (fruits from unnetted rows were smaller) and maturity (fruits from unnetted rows matured slightly faster). Fruits produced under nets had fewer microcracks at the surface than fruits produced without nets. Reduced cracking possibly helped decrease sooty blotch and flyspeck incidence and severity. Impacts for pest control and prospects for pesticide-free production are discussed.
... 36,37 Finally, fruit quality was not affected by net coverage, as reported previously. [38][39][40] A lower level of total soluble solids in Galaval* apples grown under netting is comparable with the previously reported reduction in total soluble solids in 'Gala' apples, but not in 'Fuji' apples grown under white-shade netting. 35 In some cases, the pearl photoselective net was also able to enhance some nutraceutical properties of the fruits. ...
Article
BACKGROUND Frequent pesticide treatments in fruit orchards increase hazards for workers, consumers and environment. Moreover, their indiscriminate and excessive use often induces resistance in pests. In the last few years, physical exclusion strategies have been proposed as an alternative for the control of insect pests. The goal of this study was to evaluate the effectiveness of an anti‐hail photoselective net in protecting apples against key and emerging pests as well as the impact on beneficial arthropods, fungal diseases and fruit quality. RESULTS In netted plots, a significant reduction of pest populations [i.e. fruit moths, Halyomorpha halys (Stål) and Drosophila suzukii (Matsumura)] was recorded in comparison with un‐netted controls. Moreover, the damage on fruits caused by H. halys was reduced up to 62% compared with insecticidal treatments. The net did not negatively affect the abundance of predators and the incidence of postharvest rots. In addition, the incidence of bitter pit on apple was reduced up to 52%. Furthermore, the fruit quality was unaffected by the net coverage (both at harvest and after 4 months of storage). CONCLUSION The anti‐hail photoselective pearl net proved to be a promising exclusion system that can prevent the attack of more than one insect pest at a time, allowing a strong reduction of insecticide treatments and the relative costs. At the same time, the net did not negatively influenced the presence of predators, the incidence of fungi disease and the fruit quality. This article is protected by copyright. All rights reserved.
... Plants inside net measured tallest (38.99 cm), followed by mulched treatments and control (20.06 cm). The possible reason for the positive effect on growth variables is due the enhancement of microclimate by nets [21]. ...
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Broad leaf mustard (BLM) (Brassica juncea L. var. rugosa, Brassicaceae) is one of the most widely consumed vegetable crops in Nepal. The production of crop in open field is constrained by major pests like mustard aphid and flea beetle. This study was aimed to determine the effects of pest exclusion net (PEN) on pest-infestation and yield of BLM cultivar "Khumal Broad Leaf". The experiment was carried out in randomized complete block design (RCBD) with five treatments and four replications. The treatments included control (no mulch + no net + no pesticide spray), black plastic mulch only, reflective plastic mulch only, black plastic mulch + no net + pesticide spray, and PEN + black plastic mulch + no pesticide spray. Data were analyzed with RSTAT software package and means were separated by Duncan's multiple range test (DMRT) at 5% level of significance. The result revealed that crop under PEN had highest plant height (38.99 cm), lowest number of aphid (0-0.86 per plant), flea beetle (0-1.07 per plant) and highest total marketable yield (77.50 ton/ha) while control had lowest plant height (20.06 cm), highest number of aphid (maximum 2.49 per plant), flea beetle (maximum 2.00 per plant) and lowest total marketable yield (13.75 ton/ha). Economic analysis revealed highest benefit-cost ratio in PEN (9.90). This study indicates that the use of PEN protect BLM against aphid and flea beetle, increases yield and can be considered as a viable technology for BLM production by smallholder growers of Nepal.
Article
Protective nets are commonly used in orchards to prevent hail damage and sunburns. However, these nets partially prevent sunlight exposure of the trees. Sunlight directly influences plant physiology. In present study, the effects of reduced sunlight on mineral nutrition of trees were investigated. Experimental orchard had protective nets with different shading ratios (0, 32, 42 and 56%) for 7 years. In 8, 9 and 10th year of the orchard, to reveal relationships of protective nets and mineral nutrition, apple trees were sampled from part of leaves, bud, and flower and subjected to mineral analyses. Leaf nutrients were all influenced by light intensity and increasing N, K, Fe, Cu, Mn and B levels were observed with increasing shading ratios. In fruit buds, shading treatments all had more Ca, Fe and Cu concentrations. In flower samples, only P and Mg were found to be significant and the lowest values were obtained from the greatest shading ratio. Nutrient ratios were assessed for each sample group and only the leaf nutrient ratios were found to be significant. It was observed when the common ratios (N:K and K:Mg) were assessed that the greatest N:K ratio was obtained from the control treatment and the other treatments were placed into the same group; the lowest K:Mg ratio was obtained from the control treatment and the other treatments were placed into the same group. It couldn’t be detected any relationships between decreasing yield, morphological traits and reduced sunlight with nutrient contents based on concentrations under experiment conditions.
Poster
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Overhead netting or screens mediate the effect of heat stress on climate-sensitive crops, mostly fruits, nuts, and selective cereals. Despite their widespread use, the impacts of reduced solar radiation and altered wind profile induced by the netting of the canopy microenvironment have not been modeled extensively. This study analyzes the ecophysiological response of orange (Citrus sinensis 'Valencia') orchard under netting in two different ecological zones: California, USA, and the province of Valencia, Spain. In this attempt, MLCan (multi-layer canopy) model is used to develop ecohydrological characterization for two specific sites between 2014 and 2018. The model uses atmospheric forcing inputs obtained from the ERA-5 data and site-specific canopy and soil parameters known from secondary literature. We develop a mixing-length model to evaluate the wind profile between the flux tower and ground surface with netting included. Based on the results of previous studies, we consider the wind speed to decrease by 40% due to netting and explore the resulting impact on the orange canopy microclimate. Netting shows a decrease in the latent heat flux during all months except July and August, implying reduced water use for crops with netting. Results also show an increase in the net carbon uptake at the start of the growing season and a decrease during the growing season. This dependence on the growing season is attributed to the reduced sensible heat flux and leaf temperature caused by reduced incoming solar radiation under shade netting. The differences in impacts of shade netting between the two sites highlight the significance of leaf area density. In general, the higher the leaf area density, the more substantial the change in surface energy fluxes under netting. Overall, study findings depict the usefulness of shading nets to control the fruit canopy microclimate and reduce the impacts of climate change on climate-sensitive crops. The developed model can be further implemented to explore the effects of the netting material type and related structural attributes on the canopy microclimate for considered sites and, in general, for other places with variable canopy types.
Preprint
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When grapes reach maturity, they usually experience extremely high-temperature periods in southern China, causing premature leaf senescence, abnormal fruit softening, and fruiting period shortening. Their quality and production efficiency are also severely affected. ‘Jumeigui’ grapes were examined in terms of fruit quality and leaf senescence under shading treatments; green, blue, black, and gray aluminum foil nets were used for shading, and their spectra were measured. At the same density, shade net color significantly affected cooling and shading efficiencies, and gray net had the best light transmission and cooling effect. Shading treatment significantly alleviated abnormal grape softness during hot periods. Total soluble solids (TSS) content and grape coloration were affected under gray, blue, and green shade nets. TSS exceeded 18% under gray, blue, and green nets, meeting the requirements of first-class high-quality fruit. However, peel coloration was not notably affected under gray and blue shade nets, while the non-shading treatment produced clear heat-stress damage, especially on the edges of old leaves. The net photosynthetic rate of the bottom five old leaves under the non-shading treatment was significantly lower than that under the shading treatment, indicating that high light and heat caused premature leaf senescence. In summary, colored shade nets can reduce the temperature and light in the greenhouse, while alleviating premature senescence of perennial grape plants. However, the quality of the grapes treated using black shade nets was poor; superior quality was achieved using gray and blue shade nets. These results can be applied in future cultivation facilities during high-temperature periods.
Research
The hail-nets in fruit orchards can influence several environmental factors with specific modification of metabolism and production of plants. The aim of the present work was to study sunlight spectrum modification under six photo-selective plastic hail-nets (yellow, fluo, pearl, red, blue and grey), progressively wide spread in fruit orchards after their introduction in early 2000, in comparison with the most largely used black and neutral nets. Light spectra under the nets were measured 5 times in a fixed structure, with the nets almost perpendicular to solar light, using an array spectrometer. The spectra were measured between 320 and 800 nm, cumulating the irradiance in 40 nm intervals, on clear sunny days of September. Black nets reduced irradiance more than all other nets, while neutral nets the least. Neutral, grey and black nets induced a spectrum like solar light, but with an increasing shadow effect of 7, 20 and 24%, respectively. The photo-selective nets induced an intermediate level of shade (21% blue, 21% red, 18% yellow, 15% fluo and 13% pearl) but with specific differences in light spectra. Blue nets reduced irradiance in the interval between 600 and 720 nm more than all other photo-selective nets. Yellow and fluo nets reduced the irradiance more in the interval between 400-520 nm, while red nets between 400 and 600 nm. The irradiance in the 320-400 nm interval (Ultra-Violet A) was reduced between 4 and 6 W m-2 by all the nets (photo-selective and black), except for the neutral net, which reduced light less than 2 W m-2 in the same interval. Black nets reduced the irradiance 14 W m-2 in the 720 and 800 nm interval, more than all other colored nets, which ranged between 6 and 10 W m-2. Pearl and neutral nets reduced the least (4 W m-2). The red:far red ratio was not significantly modified by any of the photo-selective nets in comparison to that of sun light (1.23).
Article
The hail-nets in fruit orchards can influence several environmental factors with specific modification of metabolism and production of plants. The aim of the present work was to study sunlight spectrum modification under six photo-selective plastic hail-nets (yellow, fluo, pearl, red, blue and grey), progressively wide spread in fruit orchards after their introduction in early 2000, in comparison with the most largely used black and neutral nets. Light spectra under the nets were measured 5 times in a fixed structure, with the nets almost perpendicular to solar light, using an array spectrometer. The spectra were measured between 320 and 800 nm, cumulating the irradiance in 40 nm intervals, on clear sunny days of September. Black nets reduced irradiance more than all other nets, while neutral nets the least. Neutral, grey and black nets induced a spectrum like solar light, but with an increasing shadow effect of 7, 20 and 24%, respectively. The photo-selective nets induced an intermediate level of shade (21% blue, 21% red, 18% yellow, 15% fluo and 13% pearl) but with specific differences in light spectra. Blue nets reduced irradiance in the interval between 600 and 720 nm more than all other photo-selective nets. Yellow and fluo nets reduced the irradiance more in the interval between 400-520 nm, while red nets between 400 and 600 nm. The irradiance in the 320-400 nm interval (Ultra-Violet A) was reduced between 4 and 6 W m-2 by all the nets (photo-selective and black), except for the neutral net, which reduced light less than 2 W m-2 in the same interval. Black nets reduced the irradiance 14 W m-2 in the 720 and 800 nm interval, more than all other colored nets, which ranged between 6 and 10 W m-2. Pearl and neutral nets reduced the least (4 W m-2). The red:far red ratio was not significantly modified by any of the photo-selective nets in comparison to that of sun light (1.23).
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Human activities concerned with agricultural growth and productivity are touching new heights every coming day by radical changes in technologies. Protected structures have made their inroad to agriculture along with the technologies, among which shade net structures are an integral part for the progressive farmers and cultivators around the globe. This chapter is dedicated to some of the lucid details explaining various technical requirements, planning, applications, material utility, crop cultivations and future scope of research, of the shade net structure. The essentiality and scope of the protected cultivation are widening avenue of research in future.
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U eksperimentu je ispitivan uticaj različitih varijanti stratifikovanja na vreme buđenja pupoljaka i početak formiranja kalusa. Korišćenо је pet sorti i selekcije oraha: sorta Šeinovo (kontrola) i selekcije Ovčar, Elit, G-139 i G-286. Posmatrano po varijantama, buđenje pupoljaka i kalusiranje, prvo je nastupilo kod varijante sa parafinisanjem plemke i spojnog mesta stratifikovani strugotinom do spojnog mesta i prekriveni polietilenskom folijom. Ova obeležja su kasnije registrovana kod varijante sa parafinisanjem plemke i spojnog mesta stratifikovani strugotinom do vrha plemke. Najkasnije, buđenje pupoljaka i parafinisanje je bilo kod varijante bez parafinisanja kalemova potpuno prekriveni četinarskom strugotinom tj. do vrha plemke. Sorte i selekcije takođe su se razlikovale u vremenu kretanja pupoljaka i pojave kalusa. Buđenje pupoljaka i formiranja kalusa prvo je nastupilo kod sorte Šeinovo i selekcija Ovčar i G-286, a kasnije kod selekcija G-139 i Elit.
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A low tunnel experiment at Toukh Protected Cultivation Site, Al-Qalyubia Governorate, Agricultural Research Center was performed in 2017 and 2018 seasons to investigate the influence of colored net covering on microclimate i.e., maximum and minimum air and soil temperatures, maximum and minimum relative humidity and average solar radiation, soil properties (moisture, bulk density, organic carbon, pH and nutrients availability of N. P. K) as well as on vegetative growth (plant length, number of leaves per plant, stem diameter, number of branches per plant, fresh and dry weight of plants), chemical component of leaves (chlorophyll reading, N, P and K) and yield (early and total) and its components (number of pods/plant, average pod weight, T.S.S. and fiber content in pods) of common bean plants. Seedlings of Paulista were transplanted on 15 th of August 2017 and 2018 seasons. Seven types of covering were used as treatments, divided into six net covering color i.e., white, yellow, red, blue, grey and black 40%, plus plastic transparent (low polyethylene tunnels 60-80 micron), compared with open field conditions. This investigation was arranged in randomized block design with three replicates. Results reflected that, generally, using colored net covering led to modify microclimate parameters and enhanced almost tested characters of soil properties, vegetative growth, component of leaves and yield and its components. Furthermore, white net cover followed by yellow net cover were the most suitable cover for increasing productivity and quality of common bean plants.
Article
Use of protective coverings can be an economically viable option in fruit nurseries than in fully mature commercial orchards. In protected nurseries, photoselective coverings can influence the growth of rootstocks, budding success, and budding growth of the budded scion cultivar. The effect of photoselective coverings (white, silver, green, red and stainless steel net house) along with open conditions (control) was studied on plant growth, nutrient uptake and root growth of rough lemon and Carrizo citrange rootstock seedlings which were subsequently budded with Kinnow and Daisy mandarin cultivar buds, respectively. The rough lemon plants under red net had better height, internodal length and budding success, while in open conditions, higher seedling diameter, root diameter, shoot and root dry weight, leaf number and secondary root number were recorded in rough lemon seedlings. The Carrizo seedlings in red net had better seedling diameter, internodal length, leaf area and number, shoot dry weight and budding success. The higher nitrogen, phosphorus, potassium and zinc levels were recorded in the leaves of rough lemon and Carrizo citrange under red shade net. The plant height of rough lemon seedlings was positively correlated to internodal length, budding success and leaf areaas well as leaf phosphorus and iron levels. The highest buddable seedlings were recorded in open conditions but, budding success in red shade net house. The highest sprout lengths of Kinnow and Daisy mandarin saplings were recorded in red net followed by green net and white net. Higher photosynthesis and stomatal conductance were recorded under red shade net, whereas lowest PAR interception was recorded in open conditions.
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Light is prerequisite for plant growth and production of quality fruit. Management of different aspects of light viz. quantity, quality and duration promises to provide a new technological alternative to sustainable production of horticultural crops. Litchi is very sensitive to climatic aberrations. The growth, panicle emergence time, flowering behavior, yield and quality of fruits have been found to be influenced by the impact of climate change. Under changing climatic conditions and consumer’s demand, light can be managed by pruning and raining, bagging of fruit bunches, use of photo-selective shade nets and reflective films in orchards. These concepts, involved in optimization of light quantity and quality, have significant effect on the litchi tree responses and practically feasible tools for sustainable management of yield and quality in modern litchi orchards. Canopy management in litchi improves the ability of sunlight to penetrate the tree, enhances the colour of fruit and improves quality. Pruning resulted in increased photosynthetic efficiency of litchi plants due to improved light penetration inside the trees. Similarly bagging of fruit bunches and use of shade net has been reported to produce more class-I fruit by reducing incidences of sun-burn and cracking of fruits. This review attempts to bring together research on effect of light on fruit quality and how manipulation of light can be achieved through different practices in the orchard towards quality fruit production under changing climatic conditions.
Article
The effect of pressure-increase rate (PIR) using the pressure-chamber technique on stem water potential measurements was studied in field-grown trees of apple (Malus domestica), nectarine (Prunus persica) and pear (Pyrus communis). Two aspects were examined: 1. The effects of five continuous PIRs from 0.03 up to 0.3 MPa s-1; 2. The effects of various PIRs at the beginning of the measurement (0.03, 0.14 and 0.3 MPa s-1) followed by a low PIR (0.03 MPa s-1) close to the endpoint. Midday stem water potential readings decreased with increasing PIR in apple, pear and nectarine. Stem water potentials at the lowest PIR were lower by about 0.03 MPa than the values obtained by extrapolating to zero PIR. Stem water potential increased with increasing initial PIR followed by 0.03 MPa s-1 towards the endpoint. Our data suggest that a PIR of 0.03 MPa s-1 is acceptable for practical irrigation scheduling in deciduous trees, and that this value should not be exceeded. High PIR at the beginning of the measurement followed by a low PIR prior to the endpoint should be avoided in deciduous trees because of an unacceptably high error. Use of a standard, continuous PIR will reduce the impact of the small inaccuracy associated with a PIR of 0.03 MPa s-1 if the thresholds for irrigation scheduling are also determined at that PIR.
Article
ADDITIONAL INDEX WORDS. greenhouse covers, greenhouse crop production, light quality, photomorphogenesis, plant growth regulation, spectral filters SUMMARY. The interest in using nonchemical alternatives for growth control of horticultural crops has recently increased due to public concerns for food safety and environ-mental pollution. Several research teams around the world are investi-gating alternative growth control measures, such as genetic manipula-tion, temperature, water and nutrient management, mechanical condition-ing, and light quality manipulation. This review discusses the recent developments in light quality manipu-lation as a nonchemical alternative for greenhouse plant height control.
Article
Light interception and leaf area distribution were measured on four planting systems of cultivar ‘Golden Delicious’ and cultivar ‘Karmijn de Sonnaville’ on M.9 rootstock at tree densities ranging from 2000 to 8333 trees ha−1. Leaf area index (LAI) varied from 1.4 for ‘Golden Delicious’ at 2000 trees ha−1 to 3.3 at 8333 trees ha−1. For the same trees, light interception increased from 49 to 83%. Yield was closely related to light interception. Trees at the more rectangular arrangement of 2.75 m × 0.8 m intercepted less light than trees at 2.0 m × 1.25 m, despite the latter having a lower tree density. Summer pruning reduced the leaf area by 10–30% and light interception by 6–14% (based on the pre-summer pruning level). Leaf dry weight per unit area was closely related to irradiance within the canopy.
Coloured shade nets can improve the yield and quality of green decorative branches of Pittosporum variegatum
  • M Oren-Shamir
  • E E Gussakovsky
  • E Spiegel
  • A Nissim-Levi
  • K Ratner
  • R Ovadia
  • Y E Giller
  • Y Shahak
Oren-Shamir, M., Gussakovsky, E.E., Spiegel, E., Nissim-Levi, A., Ratner, K., Ovadia, R., Giller, Y.E. and Shahak, Y. 2001. Coloured shade nets can improve the yield and quality of green decorative branches of Pittosporum variegatum. J. Hort. Sci. Biotech. 76:353-361.
Coloured nets can replace chemical growth regulators. FlowerTECH
  • A Priel
Priel, A. 2001. Coloured nets can replace chemical growth regulators. FlowerTECH. 4:12-13.
Growing Aralia and Monstera under colored shade nets
  • Y Shahak
  • T Lahav
  • E Spiegel
  • S Philosoph-Hadas
  • S Meir
  • H Orenstein
  • E Gussakovsky
  • K Ratner
  • Y Giller
  • S Shapchisky
  • N Zur
  • I Rosenberger
  • Z Gal
  • R Ganelevin
Shahak, Y., Lahav, T., Spiegel, E., Philosoph-Hadas, S., Meir, S., Orenstein, H., Gussakovsky, E., Ratner, K., Giller, Y., Shapchisky, S., Zur, N., Rosenberger, I., Gal, Z. and Ganelevin, R. 2002. Growing Aralia and Monstera under colored shade nets. Olam Poreah, July issue 13:60-62 (in Hebrew).
Light interception and utilization by orchard systems
  • J E Jackson
Jackson, J.E. 1980. Light interception and utilization by orchard systems. p.208-267. In: J. Janick (ed.). Horticultural Reviews Vol. 2. The AVI Publishing Company Inc., Westport. Connecticut.