Shade Levels Research Articles

Effect of para-net shade level on plant microenvironment, growth, and yield of three strawberry varieties

Abstract. Suminarti NE, Sebayang HT, Maghfoer MD, Bulan. 2023. Effect of para-net shade level on plant microenvironment, growth, and yield of three strawberry varieties. Biodiversitas 24: 2149-2155. Plant environmental management through the application of para-net shade and the selection of adaptive varieties for strawberry plants has been carried out from March to June 2020 in Jatikerto.The study used a split-plotdesign by placing shade treatments on the main plot consisting of four types, namely without shade (0%), 25% shading, 50% shading, and 75% shading, while the variety treatment was placed in subplots consisting of three kinds, namely Sweet Charlie, California, and Earlibrite varieties.The 5% F test was used to determine the interaction or significant effect of the treatments, while the 5% HSD test was used to determine differences between treatments.The results showed that there was a significant interaction in observing fruit weight per hectare. In the treatment without shade and with 25% shade, the highest fruit weight was produced by the California variety, 1.06 t ha-1,and 0.80 t ha-1, respectively. Whereas at 50% shade, the highest fruit weight per hectare was found in the Sweet Charlie variety, namely 0.66 t ha-1, and at 75% shade, higher yields were found in the Sweet Charlie and Earlibrite varieties, each of 0.65 t ha-1and 0.55 t ha1. Conclusion: California is a fairly tolerant variety to be developed in the Jatikerto area.

Morfofisiologia e qualidade de mudas de Alibertia edulis cultivadas sob contrastes luminosos e resíduo orgânico

ABSTRACT Organic residue in the substrate and the availability of light influence the production of high-quality seedlings for ex situ cultivation of native forest species. This study aimed to evaluate the effect of doses of chicken manure incorporated in the soil and shading levels on the morphophysiological responses and quality of Alibertia edulis (Rich.) A. Rich seedlings. Five doses of chicken manure (CM) were tested, 0.00, 2.08, 4.16, 6.24, and 8.32 g CM kg-1 soil, under two shade conditions, 0% (full sun) and 50% shading. At 215 days after transplanting, the maximum height obtained for A. edulis was 47.35 cm with 5.64 g CM kg-1 soil under 50% shade. Shaded seedlings had a higher number of leaves. The maximum leaf and root areas were 796.64 and 118.83 cm2 with 5.32 and 4.21 g CM kg-1 soil, respectively, both under 50% shade. Seedlings in 0% shade had lower physiological indices. Shading levels did not affect stomatal limitation, but CM contributed to physiological efficiency. Shoot biomass was higher under 50% shade with higher CM doses. The highest quality indexes occurred with 3.98 and 6.28 g kg-1 CM under 0 and 50% shade, respectively. A. edulis seedlings responded positively to the addition of CM to the soil and presented plasticity under contrasting light conditions. A. edulis seedlings produced under 50% shading with the addition of 6.24 g CM kg-1 soil presented high morphophysiological and seedling quality indicators. The addition of 4.32 g CM kg-1 soil contributed to high seedling quality under full sun conditions.

Direct NIR spectral determination of genetic improvement, light availability, and their interaction effects on chemically selected yerba-mate leaves

Monitoring plant chemical modifications provides useful information about plant genetic variability owing to environmental stresses. This allows determining if the pattern of chemical compounds of interest remains constant. Classically, chemical compounds are monitored through classical analytical procedures that are costly and environmentally harmful. Decaffeinated and high caffeine yerba-mate trees were selected based on their chemical profiles. Their behavior was evaluated at five different shading levels (0%, 40%, 51%, 76%, and 82%), imitating the environmental characteristics of yerba-mate in agroforestry systems. Near-infrared spectroscopy (NIR) fingerprints were obtained for yerba-mate leaves, and ANOVA-simultaneous component analysis (ASCA) models were developed for chemical monitoring. The preprocessing of NIR spectra was assessed with a three-level full factorial design. The best preprocessing set of conditions found was standard normal variate followed by second derivatives, computed according to the Savitzky–Golay method (11-points window and second-degree interpolating polynomial). The ASCA models satisfactorily showed significant differences in chemical behavior for genetic improvement and its interaction with light availibility effects. The genetic improvement effect had a variance of 44.30% over NIR fingerprints, indicating that the chemical differences are maintained at any light level. The interaction effect with 1.84% of the total variance illustrated that the behaviors of decaffeinated and high-caffeinated yerba mate were different when subjected to the same light level. The main absorptions indicated by the ASCA model were the O-H stretching and bending combination band at 1654 nm, and the –CH stretching aromatic 1st overtone at 1675 nm. The ASCA method offered a powerful tool for monitoring chemically selected plants combined with NIR spectroscopy. The method is cheap, fast, environmentally friendly, and can be used for field research.

Appropriate Cold Treatment Periods and Shading Levels on Codonopsis lanceolata for Plug Seedling Production in Summer Season

Codonopsis lanceolata (S. et Z.) Trautv. is mainly cultivated in Korea and China as a medicinal crop. C. lanceolata is difficult to produce plug seedlings in the summer, because C. lanceolata has a low germination rate and is vulnerable to high temperatures. Cold treatment is effective in breaking dormancy of seeds and increasing the germination rate. Shading cultivation can control the solar irradiance received by plants and reduce the damage by high temperatures and strong light. This study was conducted to examine the appropriate cold treatment period for the improving germination of C. lanceolata, and shading level during the summer seedling period. Cold treatment experiments were conducted for 0 (control), 1, 2, 3, and 4 weeks at 4°C before sowing. In the shading experiment, C. lanceolata was grown for 45 days with 0 (non-treatment), 45, 75% shading levels. Cold treatment for one week significantly improved the germination energy. The plant height, leaf area, and fresh and dry weights of C. lanceolata seedlings were significantly increased under the 45% shading level. Total root length, root surface area, and the number of root tips were significantly higher in shading treatment (45 and 75%) than in non-treatment. The C. lanceolata seedling’s compactness and Dickson’s quality index were the highest at 45% shading level. Therefore, these results recommended sowing C. lanceolata after cold treatment for one week at 4°C, and 45% shading level could stably culture C. lanceolata plug seedlings during the high temperature period.

METHOD OF COUNTING OBJECTS IN AN ORCHARD IN REAL TIME

The paper proposes a novel method for counting apples in an orchard using unmanned aerial vehicles (UAVs), also known as drones. The authors acknowledge that traditional methods of counting apples are time-consuming and labor-intensive and therefore propose a more efficient and accurate solution using a group of drones equipped with high-resolution cameras. The proposed method involves using a convolutional neural network (CNN) called YOLOv5-v1 to detect and count the apples in the images captured by the drones. YOLOv5-v1 was trained using a dataset of annotated images of apples in different lighting conditions and orientations and was found to be highly accurate in identifying and counting apples in test images. The proposed method was tested on two different orchards and was highly accurate. Specifically, the results of the experimental studies show that the model accuracy was: i) in sunny weather – 92.11%, ii) in cloudy weather – 90.76%, and iii) in sunny weather, but with high shading – 82.69%. Such results indicate that under sunny and overcast weather conditions with a low level of shade, the proposed approach demonstrates high accuracy and reliability in real-time operation. At the same time, it should be noted that due to the presence of significant visual noise in the orchard, such as the covering of fruits by leaves and branches, the efficiency of the UAV group and the automated system, in general, cannot be 100% fulfilled in natural conditions, which can serve as a promising task for further of research. Overall, the proposed method of counting structural objects provides an efficient and accurate solution for counting apples in orchards, which could save time and resources for farmers. The use of UAVs and CNNs in agriculture is a promising area of research, and this paper presents a practical application of these technologies in fruit counting.

An Improved Photovoltaic Module Array Global Maximum Power Tracker Combining a Genetic Algorithm and Ant Colony Optimization

In this paper, a hybrid optimization controller that combines a genetic algorithm (GA) and ant colony optimization (ACO) called GA-ACO algorithm is proposed. It is applied to a photovoltaic module array (PVMA) to carry out maximum power point tracking (MPPT). This way, under the condition that the PVMA is partially shaded and that multiple peaks are produced in the power-voltage (P-V) characteristic curve, the system can still operate at the global maximum power point (GMPP). This solves the problem seen in general traditional MPPT controllers where the PVMA works at the local maximum power point (LMPP). The improved MPPT controller that combines GA and ACO uses the slope of the P-V characteristic curve at the PVMA work point to dynamically adjust the iteration parameters of ACO. The simulation results prove that the improved GA-ACO MPPT controller is able to quickly track GMPP when the output P-V characteristic curve of PVMA shows the phenomenon of multiple peaks. Comparing the time required for tracking to MPP with different MPPT approaches for the PVMA under five different shading levels, it was observed that the improved GA-ACO algorithm requires 19.5~35.9% (average 29.2%) fewer iterations to complete tracking than the mentioned GA-ACO algorithm. Compared with the ACO algorithm, it requires 74.9~79.7% (average 78.2%) fewer iterations, and 75.0~92.5% (average 81.0%) fewer than the conventional P&O method. Therefore, it is proved that by selecting properly adjusted values of the Pheromone evaporation rate and the Gaussian standard deviation of the proposed GA-ACO algorithm based on the slope scope of the P-V characteristic curves, a better response performance of MPPT is obtained.

Phenology, yield, and phytochemicals of Capsicum spp. in response to shading

Background: Capsicum spp. grow in environments with different incident radiation, that could modify the plant growth and the concentration of phytochemicals in fruits.
 Hypothesis: Shading positively affects phenology and fruit yield, decreases the total contents of phenols (TPC), flavonoids (FLV), proanthocyanidins (PAN) and carotenoids (CAT) in fruits of wild Capsicum species.
 Studied species: Capsicum annuum var. glabriusculum: amashito (AMA) and garbanzo (GAR), and C. frutescens (Pico Paloma, PIP)
 Study site and dates: Huimanguillo, Tabasco, Mexico; 2020 and 2021.
 Methods: Seeds were treated with gibberellic acid (GA3) (500 mg L-1) for 24 h prior to seeding. The seedlings were transplanted in an open field and under two levels of shade (35 and 70 %) under a subsplit plot design with four replicates. TPC, FLV, PAN and CAT were determinate in immature and ripe fruits by UV-vis spectrophotometry.
 Results: Shade accelerated the phenological processes from the first bifurcation of the stem, and decreased the fruits ripening time from anthesis of the genotypes studied. Shade only increased the yield of the AMA genotype and reduced the contents of TPC, FLV, and CAT; however, these metabolites increased under open field conditions.
 Conclusions: The shade reduced the duration of phenological stages including the ripening period of fruits, and increased the plant height of the Capsicum spp. The increase in yield by shading effect only was observed in AMA genotype. The content of phytochemicals in Capsicum fruits is reduced by shading levels.

Management intensity affects insect pests and natural pest control on Arabica coffee in its native range

Abstract Agroforestry systems provide opportunities to reduce the trade‐off between agricultural production and biodiversity, for example by enhancing a diverse community of species potentially acting as natural pest control agents. While management of agroforestry systems is intensifying across the globe, we lack insights into the impact of management intensity on pest levels and natural pest control, especially along broad management gradients and as compared with natural forests. We assessed the impact of management intensity on major insect pests (the coffee blotch miner, the serpentine leaf miner, the coffee leaf skeletonizer and damage by other free‐feeding herbivores) and natural pest control by parasitoid wasps across sixty sites in the centre of origin of Arabica coffee in southwestern Ethiopia. Within this region, coffee is growing along a broad management gradient ranging from little or no management in the natural forest to intensively managed commercial plantations. In the wet season, pest levels were largely similar in the natural forest, semi‐forest and semi‐plantation systems, whereas pests reached outbreak densities in the most intensively managed plantation system. In contrast, management intensity did not significantly affect pest levels in the dry season. The insect pests differed in their seasonal dynamics, consistently declined with elevation and were largely unaffected by shade levels. Parasitism rate of the coffee blotch miner was lower, and the parasitoid community was distinct, in the most intensively managed plantation system. Synthesis and applications : Our findings support the hypothesis that the weaker top‐down control by parasitoids in the intensively managed plantation sites leads to higher pest levels, and that—at least for some pest species—there is a threshold in the effect of management intensity on pest levels and natural pest control. It is important to consider such non‐linear relationships to maintain or enhance the sustainability of agroforestry systems during management intensification. Overall, our findings highlight that ecological knowledge of natural pest control can be used to intensify production to improve the livelihood of smallholder farmers without jeopardizing natural pest control but only up to a certain point where it starts to deteriorate.

Total Phenolic, Flavonoids Contents, and Antioxidant Activities in The Stems and Rhizomes of Java Cardamom as Affected by Shading and N Fertilizer Dosages

Java cardamom is an herbal medicinal plant known as the "queen of spices." This research aims to determine the influence of shading and nitrogen fertilizer dose on the total phenolics, flavonoids, and antioxidant activity of Java cardamom stems and rhizomes. The study employed a split-plot design with two factors: the level of shading (0, 25, 50, and 75%) as the main plot and the dosage of nitrogen (N) fertilizer (0, 0.9, and 1.36 g polybag-1) as the subplots. Twelve months after planting, the rhizome and stem dried powder were extracted using the sonication-maceration technique with ethanol as the solvent. The 75% shading affected the more outstanding production of total phenolics (1.65 ± 0.59 mg GAE g-1 DW), DPPH antioxidant (4.95 ± 0.50 µmol TEAC g-1 DW), and FRAP antioxidant (8.94 ± 2.56 µmol TEAC g-1 DW) activities of the rhizomes cultivated with 0 g/polybag N in comparison to the stems of the plants. Contrary to phenolics and antioxidant activities, total flavonoids cultivated at 0% shading with 1.36 g polybag-1 N of the stems increased concentration than the rhizomes. The results indicated that the 75% shading affected the Java cardamom rhizome's phenolic content and antioxidant activities.

Effect of Shade on Xylem Development of Moringa oleifera (Alrawag) Seedlings

This study investigated the effect of shade as a moderator oflight intensity and temperature on xylem development of seedlings ofMoringa oleifera. Three levels of shade were used: high shade, mediumshade and no shade. Four sequential harvests were carried out monthly forthe seedlings starting from four weeks after seed sowing. Cross sectionswere prepared from the lower and middle parts of the stems at eachharvest and vessel volume fraction, vessel diameters, number of vesselsand volume fraction of lignified cells were measured. The results showedthat the effect of shade was significant on the anatomical variables.Generally, the values of the anatomical variables of the stem wood of theseedlings decreased with increased shade level. The findings indicate theimportance of shade to M. oleifera seedling development and that itshould be considered in nursery conditions.

The Combined Effect of Current Boosting and Power Loss on Photovoltaic Arrays under Partial Shading Conditions

This study proposes a novel technique for improving the performance of photovoltaic (PV) arrays under Partial Shading Conditions (PSCs). A 4×4 solar PV array with 16 panels was considered. Bridge-Linked (BL), Total Cross-Tied (TCT), Honey Comp (HC), One Cross-Link (OCL), and Two Cross-Link (TCL) were among the topologies of interest. First, the combined effect of connecting switches and partial shading on the PV array was studied. Then, the power loss/gain caused by reconfiguring the PV array structure from Series-Parallel (SP) to other schemes was investigated. Finally, a method of boosting current into the PV array is proposed to reduce PSCs-related power losses in the connecting switches. The results show that the number of connecting switches in the topology plays an important role in determining power gain or loss at different partial shading levels. TCT and HC outperformed the others in terms of power improvement when PSCs were considered without current boosting. This is true for different levels of solar irradiation exposure. The SP topology is optimal when the solar irradiation level is greater than 900W/m2 or less than 200W/m2. TCT outperformed the others when the current was boosted in the PV array, with a power improvement of 108%, for certain PSCs.

Coffee Berry Borer Infestation and Population per Fruit Relationship with Coffee Variety, Shade Level, and Altitude on Specialty Coffee Farms in Peru

Although the coffee berry borer (CBB) is the most important coffee pest worldwide, controversies remain regarding basic aspects of its behavior, such as how this is influenced by abiotic factors of the coffee agroecosystem. In this study, we compared the level of infestation and total population per fruit under three different levels of shade (full sun, up to 40%, and >40%), for two varieties of coffee (Caturra and Catimor) and at two different altitudes (1200 to 1700 m above sea level) in Rodríguez de Mendoza, Peru. We found that the infestation percentage increases with the shade levels of the plot. The average percentages of infestation according to shade levels were 10.52% for coffee in full sun, 12.56% with up to 40% shade, and 17.99% for coffee growing in more than 40% shade; however, maximum infestation values of 68.421%, 84.127%, and 95.238% were obtained for coffee plantations in full sun, up to 40% shade, and more than 40% shade, respectively. The Catimor variety was found to be more susceptible to CBB infestation than Caturra. In addition, CBB infestation per fruit was found to decrease with increasing altitude.

Effect of Organic Amendments and Shade Levels on Growth Performances of Diabetic Plant (Gynura procumbens)

The diabetic plant (Gynura procumbens) also recognized as a diabetic plant, contains many medicinal values but is rarely available in local markets and near at hand. Indoor gardening can help in getting the plant within reach easily. The research was conducted to investigate the growth performance of G. procumbens under various organic amendments and shade levels. The experiment was consisted of two factors: different organic amendments and shade levels. Under the first factor, three organic amendments, namely O1= Cow dung, O2= vermicompost, and O3= Trichocompost were included and under the second factor, two shade levelsviz. S1= Full shade (4×100 lux) and S2= Semi-shade (125×100 lux) were imposed. The experiment was designed in a factorial Randomized Complete Block Design (RCBD) with three replications. Plant height (cm), number of leaves, and number of stems per plant were measured and statistically analyzed at 50, 80, and 110 days after transplanting. Means were compared with the DMRT values. Results revealed that, the treatment combination of trichocompost and semi-shade (O3S2) showed highly significant maximum number of leaves (159.33) and stems (18.67) at 110 DAT (p ≤ 0.01). Trichocompost (O3) under semi-shade (S2) condition performed as the best practice for G. procumbens plant growth. Therefore, application of trichocompost under semi-shade conditions could be recommended for Gynura procumbens cultivation.

Light Intensity and Growth Media Influence Growth, Nutrition, and Phytochemical Content in Trachyandra divaricata Kunth

Trachyandra divaricata (Sandkool) is one of the most abundant wild edible inflorescence vegetables in South Africa. The dearth of literature on its edibility, nutrient composition, and conservation has contributed to its underutilisation. This study investigated mineral and proximate content, phytochemical compositions, and growth response of T. divaricata to light intensity and soilless media. Treatments comprised four media (LECA clay, silica sand, peat, and vermiculite) which were subjected to different shade levels (no shade, 20, 40, 60, and 80%) created from a factory-made 20% density net by doubling (40%), tripling (60%), and quadrupling (80%). All treatments were irrigated with a standard nutrient solution. The results showed that the treatments impacted the yield of T. divaricata significantly in terms of biomass and flower buds, especially in plants cultivated in peat under normal greenhouse lighting (no shade). Conversely, plants developed significantly more specific leaf size and total chlorophyll content under shade levels (20, 40, 60, and 80%) in different growth media, even though the values were comparable among treatments. The highest Ca, Mg, Cu, Fe, and Mn levels were consistently recorded in flowers of T. divaricata grown in LECA clay under 80% shade level, while other minerals varied in tested treatments. The peat medium under 20% shade optimised the neutral detergent fibre (NDF) and acid detergent fibre (ADF) content of the flowers, whereas both fat and protein contents were greatly enhanced by peat and vermiculite, respectively, under the 80% shade. Consistently, the lowest phytochemical contents were recorded in LECA clay subjected to 80% shade, whereas the highest polyphenols and DPPH antioxidants were produced by silica sand medium treated with 20% shade. Both TEAC and FRAP antioxidants were improved significantly in LECA clay under no shade and the 60% shade level. However, both 20% and 60% shade levels enhanced the flavonol content significantly. On the basis of these findings, T. divaricata is a promising inflorescent vegetable that may be considered for domestication and further research due to its potential pharmacological and nutraceutical values.

Survival, and anatomical and ecophysiological changes in isolated individuals of Tillandsia recurvata L. (Bromeliaceae) grown under different shading conditions

Tillandsia recurvata L. may show morphophysiological plasticity in response to radiation availability, since this species is found in different environments. This work aimed to evaluate the anatomical and physiological modifications of T. recurvata isolated individuals under different shading levels and the consequences of these changes on the growth of this species. The individuals were exposed for 60 days to treatments as follows: full sun (unshaded) and shading of 35%, 75%, and 85%. Growth analyses were performed, and the leaf anatomy and water content were assessed. All plants submitted to full sun or 35% shading died, whereas those under 75% and 85% shading survived. The water content in leaves and rhizomes was higher under 85% shading, and this treatment increased the leaf area and the number of leaves in T. recurvata. Leaf dry mass, leaf elongation rate, biomass allocation to rhizomes, and net assimilation rate were higher under 85% shading. The leaves had a thicker hypodermis, lower proportions of both epidermis and vascular bundles, and a higher proportion of chlorophyll parenchyma under 85% shading. Tillandsia recurvata individuals behave as sciophytic, while the formation of clusters may change microclimate conditions; the behavior of clumped plants must be further investigated.

Production of sage, oregano and rosemary under shading conditions and the effects of light on growth and essential oil properties

Intercropping and agroforestry systems provide sustainable land and resource use efficiency, however, shading conditions generated by the base crop or tree cover is a restricting factor on the growth of the intercrop and productivity of the system. Hence, a two-year field experiment was carried out to assess the yield, essential oil properties, morphological changes, and anatomical adaptation of the shade-exposed sage (Salvia officinalis L.), oregano (Origanum onites L.) and rosemary (Rosmarinus officinalis L.) plants. Plant height, leaf area, chlorophyll content, herbage yield, essential oil content and biochemical profile of the selected species were comparatively examined under open-field, 40% and 75% shading conditions. Initially, after the seedlings were transplanted to the field, a horizontal growth of shaded plants, resulted in lower plant height, then, after the plants covered the soil surface, vertical growth was observed. Overall drug herbage yield decreased by 65% due to the shading treatments in the first year whereas rosemary, sage and oregano had 20.9%, 25.3% and 40.3% lower yields respectively in the second year. Average essential oil content of low-light exposed plants increased by 23% and 41% first and second year of the experiment, respectively. A negative linear relation between α-thujone content in essential oil of sage and shading level was recorded while in contrast, carvacrol content of oregano essential oil increased by shade treatment. The results concluded that herbage yield and quality properties of shaded plants were promising, especially after the first year, considering their potential in intercropping and agroforestry systems. Since the current study represented the results for artificial shading conditions, the tree-based intercropping studies needed to be performed with these species for the final conclusion.

Como o tipo de estaca e níveis de sombreamento influenciam a propagação vegetativa de Pereskia aculeata?

Information from Pereskia aculeata Miller (Cactaceae) responses regarding the portion of the stem cuttings branch parental plants and the shading level need to be investigated in order to establish techniques for their producing seedlings. We aimed was to evaluate the effect of cutting types and shading levels in the production of P. aculeata seedlings. We studied three cutting types, collected from different portions of the stem cuttings branch: herbaceous, semi-hardwood, and hardwood, which were arranged under two shading levels: 0% (full sun) or 50% (shade). The selected parent plants had an adequate and vigorous phytosanitary aspect. After 90 days after the cuttings, the seedlings were evaluated regarding survival, growth indicators, biomass production and partitioning, and allometric indices. Seedlings from hardwood cuttings and produced under 0% shading showed higher survival. The largest number of sprouts occurred in seedlings of semi-hardwood and hardwood cuttings. The highest leaf area values ​​occurred in seedlings of semi-hardwood and hardwood cuttings under 0% shading. Seedlings from hardwood cuttings had higher biomass allocation in the roots under 50% shading. Seedlings of herbaceous and semi-hardwood portion allocated values ≥ 70% of the biomass in the aerial part. Seedlings of species are able to adjust to different shading levels as a plasticity mechanism. For the production of P. aculeata seedlings, the hardwood portion of the stem cuttings branch under full sun cultivation is recommended. In addition, semi-hardwood cuttings grown under 50% shading can also be used for seedlings production.

Sombreamento e época de cultivo no desempenho agronômico de jambu

ABSTRACT The jambu (Acmella oleracea) production can be influenced by the growing season and light available for metabolic processes. This study aimed to assess the agronomic and physiological performance of two jambu varieties, under different shading levels, during the winter and summer of the Brazilian Amazon. Two random block experiments were conducted, in a 2 x 4 factorial scheme, consisting of two jambu varieties (yellow and purple flower) and four shading levels (0, 30, 50 and 70 %), with four replications. Physiological, growth and yield traits were assessed. There was no significant interaction between treatments and growing seasons (Amazon winter and summer) for growth or yield traits, nor between treatments for the physiological characteristics. The cultivation without shading screen can increase the shoot dry weight of both varieties; the yellow flower variety exhibited early-onset flowering regardless of the shading screen used; the “Amazon summer” growing season increased the jambu yield by 33 %, while the 70 % shading reduced the net photosynthetic rate, consequently not favoring the vegetative development of the jambu plants. As such, it is recommended that the yellow and purple flower jambu varieties be grown without shading screen in the Amazon summer.

Exploring the cooling effect of shading for climate change adaptation in coffee areas

Rising air temperatures are the main reason for the expected reduction in land suitability for coffee cultivation under climate change in Central America. One of the reasons farmers use shade trees is to create a cooler microclimate in coffee plantations located in warming areas; therefore, adjusting the shade levels could alleviate future high temperatures. Even though data on expected climatic changes are available, no studies have addressed the cooling potential of shading in coffee production systems. In this study, we use regional climate information (RCP 4.5) and a simple shade model to explore the potential of shading as an adaptation practice in the coffee areas in Central America. A model was developed to estimate the required shade levels for Coffea arabica L. based on mean air temperature. Modeled and observed shade data were compared. Results indicate that compared to 2000, an overall increment of 23 ± 18% of shading would be required to alleviate the warming conditions by 2050. The shading will be more beneficial to coffee areas at medium and high altitudes than to areas at low ones. Also, the number of coffee areas that require dense shade levels (shading > 60%) may double by 2050. This would lead to a boost in tree biomass (carbon content) but also increase the competition for the coffee plants and consequently affect coffee yields. Trade-offs between adaptation, mitigation, and productivity objectives are expected in the coffee areas in the future.

Shading minimizes the effects of water deficit in Campomanesia xanthocarpa (Mart.) O. Berg seedlings.

The objective of this study was to evaluate the activity of antioxidant enzymes, the functioning of the photosystem II and quality of C. xanthocarpa seedlings cultivated under intermittent water deficit and shading levels and the influence of shading on recovery potential after suspension of the stress conditions. The seedlings were subjected to three levels of shading (0, 30, and 70%), six periods of evaluation (start: 0 days; 1st and 2nd photosynthesis zero: 1st and 2nd P0; 1st and 2nd recovery: 1stand 2nd REC; and END), and two forms of irrigation (control: periodically irrigated to maintain 70% substrate water retention capacity, and intermittent irrigation: suspension of irrigation). The plants subjected to intermittent irrigation conditions at 0% shading showed a reduction in water potential (Ψw) and potential quantum efficiency of photosystem II (Fv/Fm) and maximum efficiency of the photochemical process (Fv/F0) and an increase in basal quantum production of the non-photochemical processes (F0/Fm). Superoxide dismutase (SOD) activity was higher in the leaves than in the roots. The C. xanthocarpa is a species sensitive to water deficit but presents strategies to adapt to an environment under temporary water restriction, which are more temporary are most efficient under shading. The seedlings with water deficit at all levels of shading exhibited higher protective antioxidant activity and lower quality at 0% shading. The shading minimizes prevents permanent damage to the photosystem II and after the re-irrigation, the evaluated characteristics showed recovery with respect to the control group, except POD and SOD activities in the leaves.