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

Cherry laurel (Prunus laurocerasus L.) is an ornamental shrub used mainly for hedges. It is tolerant of pruning and air pollution, making this species ideal for urban horticulture. Cherry laurel is propagated commercially by stem cuttings, which are rooted in the period from June to April. Nets have long been used in horticulture against hail, wind and excessive sunlight. Recently, a new technology of photoselective nets has appeared. They are not only used for plant protection, but also stimulate the desired physiological plant responses by spectral manipulation and improve light utilization by scattering. This study was conducted in 2019 and 2020 in the nursery garden of the Faculty of Forestry and Wood Technology, Zagreb, Croatia. Rooted cherry laurel cuttings from a heated greenhouse were transplanted into outdoor beds on June 28, 2019, at 10 x 20 cm spacing in rows with a north-south orientation. Three photoselective nets were used: a white, yellow, and red net (AGRITECH S. r. l., Eboli, Italy) and a standard green shade net as control. In each treatment, 30 rooted cuttings plus grafts were transplanted, for a total of 120 cuttings. The following morphological variables of the seedlings were measured: Height, root collar diameter, root collar cross-sectional area (TCSA), slenderness coefficient, number of first-stage branches in the lower third of the plant, total number of first-stage branches, total length of first-stage branches in the lower third of the plant, total length of all first-stage branches, and average length of first-stage branches in the middle part of the plant. The measurement was performed on June 9, 2021. Data were statistically analyzed using SAS Ver. 9.4 statistical software (SAS Institute, NC) using ANOVA and Tukey's HSD test (P ≤ 0.05). The main objective of this study was to investigate the possible effects of different colored photoselective nets on the vegetative characteristics of cherry laurel. The results show that there are no statistically significant differences in all the above vegetative traits of cherry laurel seedlings grown under different types of nets. Therefore, green shade netting can be used for cherry laurel seedlings in nurseries. Further studies are needed to test this technology under other agroecological conditions.

Local varieties represent a heritage for plant biodiversity and, thanks to their resilience, are characterized by a better adaptation and rusticity to environmental variables. This work reports the morphological and physiological responses of a local ecotype of sweet pepper grown in Southern Italy, i.e., Altino, to N and light supplied at optimal and sub-optimal levels. In 2017, two open-field experiments were set up, comparing increasing N rates (0, 100 and 200 kg N ha−1, 0_N, 100_N and 200_N, respectively) and different percentages of shading and/or manipulations of the transmitted solar radiation, obtained through photoselective nets (red net, RN, black net, BN, unshaded Control). The unfertilized plants reduced growth (by 32% on average, at 83 days after transplanting, DAT), especially in terms of number of leaves, leaf area and effectiveness (chlorophyll content) of photosynthetic apparatus, no differences were recorded among fertilization treatments. On the other hand, the shading avoidance mechanisms resulted in higher biomass partitioned to leaves at the expense of sink organs, the building of more expanse (higher total leaf area) and thinner (higher specific leaf area and lower leaf-cuticular waxes) photosynthetic apparatus, and in a greater concentration of leaf pigments. The effects on yield and fruit quality of Altino ecotype deserve to be further explored.

O kiwi, fruto produzido pela Actinidia deliciosa, ? uma esp?cie que rapidamente se tornou um caso de sucesso em Portugal, quer em termos do interesse dos consumidores quer no que diz respeito ? sua produ??o. Mesmo sendo uma cultura bem-adaptada, as plantas do kiwi s?o muito sens?veis aos danos causados pelo granizo e pelo vento e, nos ?ltimos anos, tem vindo a ser muito afetada pela Pseudomonas syringae pv. actinidiae (Psa), bact?ria respons?vel pela doen?a que mais preocupa os produtores. Em Portugal, a Psa foi identificada pela primeira vez em 2010, provocando perdas que podem atingir mais de 80% da produ??o, tornando essencial a investiga??o e o desenvolvimento de estrat?gias eficazes na conten??o da doen?a. Recentemente, a utiliza??o de redes foto-seletivas na cultura de kiwi permite combinar a prote??o f?sica com a sele??o de determinadas faixas do espectro da radia??o solar para promover respostas fisiol?gicas desejadas que sejam reguladas pela luz. As redes t?m sido usadas para proteger as plantas contra granizo, vento, excesso de radia??o solar, pragas e doen?as, melhorando a sa?de das plantas e a qualidade dos frutos. Assim, o presente trabalho teve como objetivo avaliar a influ?ncia de redes foto-seletivas na incid?ncia de Psa, na produtividade e qualidade dos frutos de kiwi. O ensaio foi realizado num pomar de kiwis da cv. Hayward, instalado no ano de 1988 na explora??o agr?cola ?Quinta das Picas?, da empresa KIWI GREENSUN, em Guimar?es. As redes foto-seletivas utilizadas (Iridium ?, Agrintech) de cor p?rola, amarela e cinzenta, tinham um efeito de sombreamento de 7%, 4% e 19%, respetivamente, e foram instaladas horizontalmente acima das plantas, em maio de 2019. A severidade da Psa foi avaliada nas folhas por uma escala de severidade (Vanneste et al., 2013). Os principais efeitos das redes foram a diminui??o da radia??o fotossint?tica ativa (entre 7,9% e 11,3%), diminui??o da velocidade do vento, aumento da propor??o da radia??o azul/vermelho, maior efeito de difus?o da luz, aumento da temperatura m?dia do ar (entre 0,3?C e 0,7?C) e diminui??o da humidade relativa m?dia di?ria do ar (entre 1,4% e 2,6%). A severidade da Psa foi menor nas plantas sob as redes em compara??o com o controle, provavelmente devido ?s condi??es clim?ticas que prejudicaram o desenvolvimento e a dispers?o da bact?ria. As plantas sob a rede p?rola em compara??o com o controle, tiveram menor severidade de Psa, aumento de 33% na produtividade e maior firmeza e teor de mat?ria seca dos frutos ap?s 14 semanas de armazenamento refrigerado. Cobrir o pomar de kiwi com a rede foto-seletivas p?rola parece ter um impacto ben?fico na progress?o da doen?a de Psa, na produ??o, na qualidade p?s-colheita dos frutos e na capacidade de armazenamento. The Kiwi, a fruit produced by Actinidia deliciosa, is a species that quickly became a success story in Portugal, both in terms of consumer interest and in terms of its production. Despite being a well adapted crop, kiwi plants are very sensitive to damage caused by hail and wind and, in recent years, have been very affected by Pseudomonas syringae pv. actinidiae (Psa), bacteria responsible for the disease that most concerns producers. In Portugal, Psa was first identified in 2010, causing losses that can reach more than 80% of production, making research and the development of disease prevention essential. In terms of terms, the use of photo-selective nets in kiwi culture allows combining physical protection with the selection of bands in the spectrum of solar radiation to promote desired physiological responses that are regulated by light. Nets were used to protect plants against hail, wind, excessive solar radiation, pests and diseases, improving plant health and fruit quality. Thus, the present study aimed to evaluate the influence of photo-selective nets on the increase in Psa, on the productivity and quality of kiwi fruits. The test was carried out in a kiwi orchard of cv. Hayward, installed in 1988 in the farm ?Quinta das Picas?, by the company KIWI GREENSUN, in Guimar?es. The photo selective nets (Iridium ?, Agrintech) of pearl, yellow and gray color, had a shading effect of 7%, 4% and 19%, respectively, and were installed horizontally above the plants, in May 2019. A Psa severity was assessed on the leaves by a severity scale (Vanneste et al., 2013). The main effects of the networks were the decrease in active photosynthetic radiation (between 7.9% and 11.3%), decrease in wind speed, increase in the proportion of blue / red radiation, greater light diffusion effect, increase in temperature average air (between 0.3 ? C and 0.7 ? C) and decrease in the average daily relative humidity of the air (between 1.4% and 2.6%). The severity of Psa was lower in plants under nets compared to the control, due to climatic conditions that hindered the development and dispersion of bacteria. The plants under the pearl net compared to the control, have lower Psa severity, 33% increase in productivity and greater firmness and dry matter content of the fruits after 14 weeks of cold storage. Covering the kiwi orchard with the photo selective pearl net seems to have a beneficial impact on the progression of Psa disease, on production, on post-harvest quality of the fruits and storage capacity.

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.

Anti-insect photoselective nets present a new technology that combines light manipulation and pest protection in orchards. In this study, the effect of the anti-insect photoselective red net on the generative and vegetative traits was studied in an apple orchard near the city of Zadar, Croatia. 'Granny Smith' apples were grown on M9 rootstock and raised as slender spindles. The experiment consisted of two treatments: the trees covered with the red photoselective anti-insect nets (AGRITECH S. r. l., Eboli, Italy; mesh size of 2.4 × 4.8 mm) and uncovered trees as control. Yield, percentage of fruit with diameter >70 mm and fruit mass were not significantly different between treatments. L* color value was higher on fruit skin grown under the red net, and there was no significant difference in other color values (a*, b*, C* and h°). Soluble solids concentration (SSC) and total flavonoid content were significantly lower in fruit grown under red net than in control, and there was no significant difference in titratable acidity (TA), SSC/TA ratio, starch degradation and Streif maturity index. Red net proved to be effective against fruit red blush development (undesirable trait for 'Granny Smith' apple) and sunburn damage occurrence., Protuinsektne fotoselektivne mreže predstavljaju novu tehnologiju koja istovremeno kombinira manipulaciju svjetlom i zaštitu od štetnika. U voćnjaku jabuka pokraj Zadra (Hrvatska) istraživan je utjecaj crvene protuinsektne fotoselektivne mreže na generativne i vegetativne parametre jabuke 'Granny Smith'. Jabuke su uzgajane na M9 podlozi te su imale uzgojni oblik vretenastoga grma. Istraživanje se sastojalo od dvaju tretmana: stabla prekrivena crvenom protuinsektnom fotoselektivnom mrežom (AGRITECH S. r. l., Eboli, Italija; veličina okca od 2.4 × 4.8 mm) i nepokrivena stabla kao kontrola. Prirod, udio plodova s promjerom >70 mm i masa plodova nisu se signifikantno razlikovali između tretmana. Jabuke uzgajane ispod crvene mreže imale su signifikantno veću L* vrijednost parametra boje kožice, dok za ostale parametre boje nije zabilježena signifikantna razlika (a*, b*, C* i h°). Sadržaj topljive suhe tvari (TST) i ukupni sadržaj flavonoida bio je signifikantno niži u jabukama uzgajanima ispod crvene mreže, dok nije zabilježen signifikantan utjecaj crvene mreže na titracijsku kiselost (TA), TST / TA, stupanj razgradnje škroba i indeks zrelosti (Streif). Primjena crvene mreže pokazala se vrlo djelotvornom u smanjenju pojavnosti dopunskoga crvenila (koje je kod jabuke 'Granny Smith' nepoželjno svojstvo) i ožegotina od sunca na plodovima.

Here we evaluate the effect of quality and quantity of light on growth and secondary metabolism of Achillea millefolium L. plants. Plants were cultivated under either full light or colored shading nets (blue, red or black). Analyzes were performed after eight weeks of shading and two and four weeks after the removal of the nets. Plants grown under nets presented lower dry weight of leaves and flowers. In addition, the synthesis of phenols and flavonoids decreased in leaves and flowers of shaded plants. On the other hand, the blue net increased the content of essential oil yield in leaves. The concentration of the majority of the compounds analyzed in the essential oil increased when using the black net. Farnesol and chamazulene were the most plenteous compounds in the oil of leaves and flowers in all conditions. Overall, these results indicate that different compounds respond differently to specific light lengths in A. millefolium plants. Thus, the photoselective treatments should be directed to the production of the target metabolite., (Plantas de Achillea millefolium L. crescidas sob sombreamento com malhas coloridas possuem alterações no metabolismo secundário). O efeito da qualidade e quantidade de luz no crescimento e metabolismo secundário foram avaliados em plantas de Achillea millefolium L.. As plantas foram cultivadas sob luz plena ou sob redes coloridas (azul, vermelho e preto) e avaliadas após oito semanas de sombreamento e após duas e quatro semanas da retirada das redes. Plantas sombreadas apresentaram menores valores de matéria seca de folhas e flores. Além disso, a síntese de fenóis e flavonóides diminuiu em folhas e flores de plantas sombreadas. Por outro lado, a rede azul aumentou o teor de óleo essencial nas folhas. A concentração da maioria dos compostos analisados no óleo essencial das plantas aumentou quando se utilizou a rede preta. Farnesol e chamazuleno foram os compostos mais abundantes no óleo essencial de folhas e flores em todas as condições. De forma geral, esses resultados demonstram como os compostos secundários respondem diferentemente à qualidade da luz em plantas de A. millefolium. Assim, os tratamentos fotosseletivos devem ser direcionados para a produção do metabólito de interesse.

O uso de telas fotosseletivas tem sido uma abordagem recente no cultivo protegido. Pode promover benefícios, além das funções de proteção das malhas de plástico. Estas telas não só agem na dispersão da luz, como agem também na modificação do espectro da luz transmitida, de modo a promover respostas fisiológicas desejadas na planta, além de melhorar a penetração da luz no interior de sua parte aérea. No Brasil, o tomate é a olerícola mais importante e tradicionalmente cultivada em campo aberto. Recentemente o uso de telas plásticas com sombreamento colorido tem sido estudado para proteger as plantas de adversidades climáticas. Este estudo teve como objetivo investigar se a combinação do adensamento de plantas, o uso de reguladores de crescimento e o efeito da malha fotosseletiva vermelha poderiam melhorar a produtividade e a qualidade dos frutos de tomateiro e promover desenvolvimento vegetativo desejado. O experimento foi realizado no período de 21 maio a 1° novembro 2014, em Goiânia, Brasil (16º35'47''S, 49 ° 16'47''W, 730 m). O híbrido Ivete da Sakata Seeds® foi cultivado sob telado vermelho e campo aberto. Índice de área foliar, altura final da planta e altura dos cachos foram medidas. O número total, peso total, diâmetro e número de frutos não comerciais foram totalizados. Foram, também, realizadas medidas físicas (massa fresca, sólidos solúveis totais (SST em °Brix), acidez titulável (AT), razão SST / AT e pH) e variáveis nutricionais (vitamina C e licopeno) em dois momentos de coleta dos frutos (98 e 129 dias após transplantio). Todas as medidas foram realizadas por métodos oficiais de análise. Frutos produzidas em campo aberto foram mais ácidos e tiveram maior acidez total titulável (0,37%) em relação aos frutos produzidos sob telado plástico (0,33%) com 0,3 m de espaçamento entre plantas. Além disso, frutos cultivadas no campo apresentaram maior teor de SST (6,6 °Brix) do que aqueles cultivados em ambiente protegido (5,4 °Brix). Além disso, as frutos produzidas no campo aberto tiveram maior Ratio (SST/ AT) do que as produzidas em um ambiente protegido. Observou-se significativamente maiores teores de licopeno em frutos cultivados sob telado vermelho (47,0 mg g-1) em 0,4 m de espaçamento do que em tomates cultivados em campo aberto (29,6 mg g-1). Os resultados mostraram que maior produtividade foi obtidos com densidade de 3 plantas por m2 em ambos os ambientes. A maior produção total de frutos ocorreu em condições de campo aberto (12,87 kg.m-2). O total de frutos perdido nas condições de campo aberto foi maior. Os resultados do presente estudo fornecem informações úteis para a detecção e compreensão de diferenças entre variações ambiente e formas de cultivo nas características agronômicas, nutricionais e fisico-químicas dos frutos de tomate. Photoselective screens are a recent approach in protected cultivation, which can promote benefits in addition of the protective functions of nettings. These nets not only scatter but spectrally-modify the transmitted light, in order to promote desired physiological responses and improve the penetration of the light into the inner plant canopy. Tomato is the second most important horticulture crop in the world. Traditionally, tomato is cultivated in the open field, but recently there has been an increase of the protect cultivation area aiming to protect plants from climate adversities. This study aimed to investigate whether a combination of growth regulator, increased plant density and the effect of red screen-shade net could improve tomato yield, quality and promote desired vegetative development. The experiment was conducted from May 21st to November 1st, 2014, in Goiânia, Brazil (16º35´47´´S, 49°16´47´´W, 730 m). The hybrid Ivete from Sakata Seeds® were cultivated in 16x12x 2.2 m3, 40% red shading screenhouse and field plots as control. Leaf area index, trusses height, and total height were measured. The total number, total weight, diameter and number of lost fruits were totaled. Nutritional analyses were also performed: physical (Fresh mass, total solid soluble - TSS, titritable acidity - TA, SST/AT ratio and pH) and nutritional parameters (vitamin C and lycopene) in two moments of collecting of fruits (98 and 129 days after transplantation). All the measures were carried by official methods. Results showed that highest yields were obtained using 3 plants per m2 in both environments. The highest total fruit production occurred in open field conditions. However, the total fruit lost in the open field conditions was greater. Fruits produced in an open field were more acidic and had greater titratable acidity (0.37% citric acid) compared to fruits from screenhouse (0.33 % citric acid) at 3 plant per square meter. In addition, fruits grown in the field had greater TSS content (6.6 °Brix) than tomatoes grown in a protected environment (5.4 °Brix). Fruits produced in the open field had greater TSS:TA ratios than those produced in a protected environment. Significantly higher lycopene content was observed in plastic-house tomatoes integrated with red shade netting technologies (47.0 μg g−1) using 2.3 plants per m² than in open field-grown tomatoes (29.6 μg g−1). The results provide useful data for detecting differences among environment variation in tomato composition and red colour shade nets. In addition, the photoselective red screen combined with the density of 3 plants per m² promoted higher yield of commercial fruits. Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES

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