Canopy Shade Research Articles

Effects of fruit tree canopy shading on grain filling of intercropping winter wheat.

Fruit tree-wheat intercropping system is the main agricultural production pattern in sou-thern Xinjiang. In this study, almond (Amygdalus communis)-winter wheat (Xindong 20 (Triticum aestivum, var. Xindong 20) intercropping system was used as the research object. Four tree forms of delayed open-central shape (DC), open-center shape (OC), high stem-shape (HS), and semicircle small-canopy shape (SC) and three intercropping distances (wheat intercropping area respectively 1.5, 2.5 and 3.5 m from the tree trunk) were set to create tree canopy shading treatments, with monoculture wheat as the control. The environmental factors and the grain filling characteristic of winter wheat under different treatment conditions were measured, and the correlation between grain filling characteristics and 1000-grain weight and environmental factors was established to provide information for selecting the best management standards and optimizing the intercropping system. The results showed that under the almond tree-winter wheat intercropping system, the PAR, red/far-red light (R/FR), and temperature above the wheat canopy were significantly decreased due to canopy shading, resulting in a significant increase in humidity. The degree of variation was affected by tree form and distance. The PAR decrease degree of the four treatments was DC＞OC/HS＞SC, except for HS. The PAR decrease of the other tree form treatments was 1.5 m＞2.5 m＞3.5 m. The PAR decrease was distributed in the range of 35.5%-86.6%. A cubic polynomial equation represented the grain filling process, and the specific property of grain filling and 1000-grain weight was assessed using the correlation analysis. The decrease in the 1000-grain weight in the intercropping system was closely associated with the decreases in average grain-filling rate (V), maximum grain-filling rate (Vmax), effective grain-filling duration (Se), and effective grain-filling duration (Vs). The shortening of Se and the reduction in the grain filling rate were related with the reduction in the PAR incidence above the wheat canopy. In the fruit tree-winter wheat intercropping system, the reduction of PAR, dry matter accumulation after flowering, and Se were reduced by tree canopy shading consequently for the decrease in the 1000-grain weight of the intercropping wheat. When the distance between the intercropping area and the tree trunk was greater than 75% of tree height, and shading intensity was less than 35.5% of the natural light intensity, the intercropping with the almond tree could increase the 1000-grain weight of wheat by increasing the effective grain-filling duration.

Performance of wheat and mustard in agroforestry system under terai conditions of U.P., India

A large area is available in the form of boundaries, bunds, block plantations, wastelands where this system can be adopted. Poplar and Eucalyptus are suitable and promising agroforestry tree species, which is planted cropping system. In this particular study, Economical aspects and viability of wheat and Mustard have been studied. Trees intercropped with crops attained better growth and higher litter. In the study of nutrients (NPK) it is reviewed that all the three nutrients increase as the age of trees increases. All the nutrients increases as the tree age are increased. It is clearly seen after the whole research work done, nutrients in the soil are high insole plantation of trees. The yield of intercrops is low in the fields which are cultivated along with trees. The height of intercrops is higher under Poplar than intercrops under Eucalyptus. This might be due to the leaf pattern and its canopy shade. No significant results were obtained for tillers per plant and effective tillers per plant in wheat, however, more tillers were found in pure cropping. In Mustard primary branches per plant and seeds per siliqua were at par under Eucalyptus, Poplar, and pure cropping. Yield parameters such as secondary branches per plant, siliqua per plant, and test weight were significantly higher in pure cropping. The grain and straw/stover yields of both the crops under Eucalyptus and Poplar decreased significantly as compared to open fields (crops without Eucalyptus and Poplar). Net returns from a crop grown with Eucalyptus, & Poplar and sole cropping revealed that maximum income (Rs.82819.00/ha) was recorded in pure cropping (monoculture) of wheat, whereas net returns from Mustard grown Eucalyptus, Poplar and sole cropping revealed that maximum income (Rs.67275.00/ha) and whereas negative net returns of Rs.3943.47/ha (under 4years Eucalyptus) and also negative net returns Rs. 8731.00/ha (under 5 years Poplar) was recorded in Mustard oil.

Phytochrome A elevates plant circadian-clock components to suppress shade avoidance in deep-canopy shade

Shade-avoiding plants can detect the presence of neighboring vegetation and evoke escape responses before canopy cover limits photosynthesis. Rapid stem elongation facilitates light foraging and enables plants to overtop competitors. A major regulator of this response is the phytochrome B photoreceptor, which becomes inactivated in light environments with a low ratio of red to far-red light (low R:FR), characteristic of vegetational shade. Although shade avoidance can provide plants with a competitive advantage in fast-growing stands, excessive stem elongation can be detrimental to plant survival. As such, plants have evolved multiple feedback mechanisms to attenuate shade-avoidance signaling. The very low R:FR and reduced levels of photosynthetically active radiation (PAR) present in deep canopy shade can, together, trigger phytochrome A (phyA) signaling, inhibiting shade avoidance and promoting plant survival when resources are severely limited. The molecular mechanisms underlying this response have not been fully elucidated. Here, we show that Arabidopsis thaliana phyA elevates early-evening expression of the central circadian-clock components TIMING OF CAB EXPRESSION 1 (TOC1), PSEUDO RESPONSE REGULATOR 7 (PRR7), EARLY FLOWERING 3 (ELF3), and ELF4 in photocycles of low R:FR and low PAR. These collectively suppress stem elongation, antagonizing shade avoidance in deep canopy shade.

A FULLY AUTOMATED AND FAST APPROACH FOR CANOPY COVER ESTIMATION USING SUPER HIGH-RESOLUTION REMOTE SENSING IMAGERY

Abstract. Canopy cover is a key agronomic variable for understanding plant growth and crop development status. Estimation of canopy cover rapidly and accurately through a fully automated manner is significant with respect to high throughput plant phenotyping. In this work, we propose a simple, robust and fully automated approach, namely a rule-based method, that leverages the unique spectral pattern of green vegetation at visible (VIS) and near-infrared red (NIR) spectra regions to distinguish the green vegetation from background (i.e., soil, plant residue, non-photosynthetic vegetation leaves etc.), and then derive canopy cover. The proposed method was applied to high-resolution hyperspectral and multispectral imagery collected from gantry-based scanner and Unmanned Aerial Vehicle (UAV) platforms to estimate canopy cover. Additionally, machine learning methods, i.e., Support Vector Machine (SVM) and Random Forest (RF) were also employed as bench mark methods. The results show that: the rule-based method demonstrated promising classification accuracies that are comparable to SVM and RF for both hyperspectral and multispectral datasets. Although the rule-based method is more sensitive to mixed pixels and shaded canopy region, which potentially resulted in classification errors and underestimation of canopy cover in some cases; it showed better performance to detect smaller leaves than SVM and RF. Most importantly, the rule-based method substantially outperformed machine learning methods with respect to processing speed, indicating its greater potential for high-throughput plant phenotyping applications.

Effects of sunlight exclusion on leaf gas exchange, berry composition, and wine flavour profile of Cabernet-Sauvignon from the foot of the north side of Mount Tianshan and a semi-arid continental climate

Canopy shading is a widely used viticultural strategy for mitigating early grape berry ripening caused by global warming. In this study, we covered half of the canopy with a black shade cloth from the pea-size stage to harvest. In the fruit zone, canopy shade treatment (ST) reduced daily average solar radiation by about 74.6 % compared to the untreated control (UC), and significantly reduced daily average temperature. ST leaves were found to have lower net assimilation rates and higher internal CO2 concentration than in UC, which resulted in reduced yield, bunch weight, cane starch and berry total soluble solids. A delayed development stage was found in ST berries which had lower pH and higher titratable acid than UC. ST increased both berry and wine anthocyanin concentration while significantly decreasing flavonol concentration. ST wines had higher concentrations of a number of ester compounds and β-damascenone than UC wines, thus significantly enhancing the floral and fruity aroma of ST wines. Higher C6/C9 and fatty acids concentrations in ST berries may have caused higher ester concentrations in ST wines. The results showed significant effects on metabolites in berries and wines caused by canopy shade.

Global carbon dioxide efflux from rivers enhanced by high nocturnal emissions

Carbon dioxide (CO2) emissions to the atmosphere from running waters are estimated to be four times greater than the total carbon (C) flux to the oceans. However, these fluxes remain poorly constrained because of substantial spatial and temporal variability in dissolved CO2 concentrations. Using a global compilation of high-frequency CO2 measurements, we demonstrate that nocturnal CO2 emissions are on average 27% (0.9 gC m−2 d−1) greater than those estimated from diurnal concentrations alone. Constraints on light availability due to canopy shading or water colour are the principal controls on observed diel (24 hour) variation, suggesting this nocturnal increase arises from daytime fixation of CO2 by photosynthesis. Because current global estimates of CO2 emissions to the atmosphere from running waters (0.65–1.8 PgC yr−1) rely primarily on discrete measurements of dissolved CO2 obtained during the day, they substantially underestimate the magnitude of this flux. Accounting for night-time CO2 emissions may elevate global estimates from running waters to the atmosphere by 0.20–0.55 PgC yr−1. Failing to account for emission differences between day and night will lead to an underestimate of global CO2 emissions from rivers by up to 0.55 PgC yr–1, according to analyses of high-frequency CO2 measurements.

Growth, death, and resource competition in sessile organisms

Population-level scaling in ecological systems arises from individual growth and death with competitive constraints. We build on a minimal dynamical model of metabolic growth where the tension between individual growth and mortality determines population size distribution. We then separately include resource competition based on shared capture area. By varying rates of growth, death, and competitive attrition, we connect regular and random spatial patterns across sessile organisms from forests to ants, termites, and fairy circles. Then, we consider transient temporal dynamics in the context of asymmetric competition, such as canopy shading or large colony dominance, whose effects primarily weaken the smaller of two competitors. When such competition couples slow timescales of growth to fast competitive death, it generates population shocks and demographic oscillations similar to those observed in forest data. Our minimal quantitative theory unifies spatiotemporal patterns across sessile organisms through local competition mediated by the laws of metabolic growth, which in turn, are the result of long-term evolutionary dynamics.

UAV-Based Estimate of Snow Cover Dynamics: Optimizing Semi-Arid Forest Structure for Snow Persistence

Seasonal snow cover in the dry forests of the American West provides essential water resources to both human and natural systems. The structure of trees and their arrangement across the landscape are important drivers of snow cover distribution across these forests, varying widely in both space and time. We used unmanned aerial vehicle (UAV) multispectral imagery and Structure-from-Motion (SfM) models to quantify rapidly melting snow cover dynamics and examine the effects of forest structure shading on persistent snow cover in a recently thinned ponderosa pine forest. Using repeat UAV multispectral imagery (n = 11 dates) across the 76 ha forest, we first developed a rapid and effective method for identifying persistent snow cover with 90.2% overall accuracy. The SfM model correctly identified 98% (n = 1280) of the trees, when compared with terrestrial laser scanner validation data. Using the SfM-derived forest structure variables, we then found that canopy shading associated with the vertical and horizontal metrics was a significant driver of persistent snow cover patches (R2 = 0.70). The results indicate that UAV image-derived forest structure metrics can be used to accurately predict snow patch size and persistence. Our results provide insight into the importance of forest structure, specifically canopy shading, in the amount and distribution of persistent seasonal snow cover in a typical dry forest environment. An operational understanding of forest structure effects on snow cover will help drive forest management that can target snow cover dynamics in addition to forest health.

Competition for space in a structured landscape: The effect of seed limitation on coexistence under a tolerance‐fecundity trade‐off

Abstract Life‐history trade‐offs are important coexistence mechanisms in plant communities. In particular, a trade‐off between seed quality and seed output may explain coexistence among species with a wide variety of seed sizes in heterogeneous landscapes with varying degrees of local stresses such as shade, drought and browsing. Under spatially implicit formulations of the tolerance‐fecundity trade‐off, species diversity is only bounded by community size and environmental heterogeneity. However, these formulations leave unanswered the question of how dispersal limitation, an important aspect of real communities, impacts the ability of the tolerance‐fecundity trade‐off to support coexistence. Here we show using stochastic cellular automata that coexistence under the tolerance‐fecundity trade‐off in a spatially structured landscape is strongly modulated by the interactions between the spatial scales of species dispersal and environmental variability. Specifically, coexistence in a patchy landscape is higher under short dispersal scales relative to the scale of environmental variation. These conditions allow species to segregate spatially and thus avoid interspecific competition. In addition to dispersal limitation, coexistence under the tolerance‐fecundity trade‐off is promoted by a sharp drop in tolerance as local environmental stress increases, a high overall seed output across species, local homogeneity in environmental conditions and weak age structure in fertility. In particular, coexistence is much higher when species have full tolerance to stress levels below a threshold and zero tolerance above that threshold, with nothing in between. This steep gradient contributes to coexistence because it maximizes niche separation between similar species. Synthesis. When plants compete for space, dispersal limitation and landscape spatial structure can conspire to boost coexistence and diversity. Our results show that the tolerance‐fecundity trade‐off is a strong niche differentiation mechanism when species experience a well‐defined distinction between suitable and unsuitable environments, and supports higher diversity when dispersal scales are shorter than the scales of variation in the environment. We conclude that the trade‐off is more likely to be a relevant coexistence mechanism in the context of large‐scale environmental variation, such as topography, than small‐scale variation, such as in litter cover and canopy shading.

Effects of fragmented mangroves on macrozoobenthos: a case study of mangrove clearance for powerline right-of-way at Oproama Creek, Niger Delta, Nigeria

Mangroves are vulnerable to varying magnitudes of degrading impact by human activities. Despite the many benefits of mangrove ecosystems, mangroves in the Niger Delta region are often cleared for electric powerline and oil pipeline rights-of-way, recreation, road construction, housing and farming. The study assessed the impacts of mangrove clearance on physico-chemical parameters of interstitial water and macrozoobenthic primary community structure in Oproama Creek, Nigeria, from February to July 2016. Three stations were selected for the study: two stations in more natural and undisturbed mangroves and one station at a mangrove clearing (for a national grid powerline right-of-way). Species richness and diversity were slightly higher at the undisturbed mangrove sites than the cleared site. Removal of mangrove canopy shade alters microclimate temperature regime and other temperature-dependent parameters, imposing thermal stress on stenothermal taxa and ancillary stressors that compositely affected primary community structure indices. Deliberate loss of mangroves through clearing waterfront vegetation as a driver for improved visual monitoring and enhanced security in the Oproama Community in the Niger Delta is reported for the first time. The wider implications of mangrove clearance and fragmentation on ecosystem-based goods and services are discussed. Limiting mangrove spatial loss owing to construction of an electric tower cutline within coastal landscape is strongly recommended.

Seed rain in cocoa agroforests is induced by effects of forest loss on frugivorous birds and management intensity

Tropical forests have been intensively degraded and deforested for different anthropogenic uses, mostly associated to agricultural expansion due to increasing human demands. Therefore, an emerging number of studies has advocated on the benefits of land-sharing strategies such as agroforestry systems which conciliate biodiversity conservation with production. Yet features at both landscape and local scales could affect ecological processes and productivity within agroforests. Here, we used structural equation models to investigate the direct and indirect effects of landscape forest cover, animal seed dispersers and local vegetation variables on the seed rain structure of cocoa (Theobroma cacao) agroforests of the Brazilian Atlantic forest. We sampled seed rain for 12 consecutive months, performed bird and bat surveys and measured local structure variables related to management intensification (i.e., lower abundance and richness of adult trees and lower canopy shading indicating farm intensification) in 15 farms embedded within landscapes showing varying forest cover amount (2.3–74.9 %). Our results indicate that total and animal-dispersed seed richness in cocoa agroforests increased in more forested landscapes induced by the frugivorous bird richness, whereas the abundance of total and animal-dispersed seeds was greater in more shaded farms. Contrary to expectations, the abundance of total and animal-dispersed trees negatively influenced the richness of frugivorous birds, thus indirectly affecting the richness of total and animal-dispersed seeds. Finally, we observed a weak similarity among the composition of arrived seeds and adult trees of animal-dispersed species recorded in the same sampling sites, suggesting that several seeds were actively dispersed from other localities. Our results therefore demonstrate that landscape forest amount and local management intensification play key roles in determining the seed diversity reaching cocoa agroforestry farms. We emphasize the importance of retaining native vegetation cover around the cocoa agroforestry, by either preserving the existing forest remnants or promoting restoration programs within deforested landscapes, in addition to locally ensure tree shading to boost seed arrival and enhance ecosystem functionality.

Survival, growth and photochemical efficiency of silver fir seedlings produced with different technologies

Forest tree seedling production technologies impact reforestation success determined with survival and quality of seedlings. Five Abies alba seedling production technologies were tested: (1) bare-root seedling, three years in the open (3/0); (2) bare-root seedling, two years under a shading net (40% of full light), a year in the open (2/g); (3) ball root seedling, two years under a shading net (40%), a year in the open (2/K); (4) bare-root seedling grown in an opening in a Norway spruce stand (3/Pic); (5) bare-root seedling, three years under Scots pine canopy (3/Pin). Silver fir seedlings acclimatized their growth rates to the common growing environment in relation to the seedling production technology used in the nurseries. The height and diameter at root collar were positively correlated with survival. The 3/Pic seedlings manifested the lowest survival and were lower than other seedlings in terms of height and photochemical efficiency. The needle photochemistry of seedlings growing two years in plantation was determined by their earlier acclimation to the nursery light conditions. The production technology determined the ability of A. alba seedlings to acclimatize to the natural environment. Ball root seedlings grown two years in shade and a year in the open (2/K) acclimatized better to the full light environment compared with bare-root seedlings produced in canopy shade, and they are likely more suitable to be planted after clearcutting.

Intercropping of Several Cultivars of Banana and Plantain under Coconut Based in North Sulawesi, Indonesia

The Research has been conducted in Pandu Experimental Garden, Talawaan Bantik Village, North Sulawesi, titled “Intercropping of Several Cultivars of Banana and Plantain under Coconut Based in North Sulawesi, Indonesia”. The aims of the research were to study suitability of several banana and plantain intercropped into coconut based farming system. The materials and methods used were monoculture coconut plantation, hybrid Khina-1 planted in 1986, designed in RCBD, 5 treatments were the banana and plantain cultivars Mas, Gapi, Gepok Tanjung, Goroho and Raja. Then the Least Significant Difference Test (LSD) was used for mean separations. Significantly, was determined at the p=0.05 probability level. In this experiment also, using t-test to compare the effect of natural shade of the coconut canopy with an open field for the five varieties tested. Then, using 20 plants for each variety and treatment, served as replication. Two dwarf cultivars, Mas (banana) and Goroho (plantain) indicated the significant vegetative and generative growth shorter than the three tall cultivars, Gapi, Gepok Tanjung and Raja. It is also concluded that coconut based using Hybrid Khina-1 varieties, spacing 8m x 8m square system is suitable for intercropping with banana and plantain, especially the Dwarf Mas and Goroho.

Land-use changes affect the functional structure of stream fish assemblages in the Brazilian Savanna

Abstract We investigated the mechanisms involved in the relationship between land-use changes and aquatic biodiversity, using stream fish assemblages of the Brazilian Savanna (i.e., Cerrado) as a study model. We tested the prediction that landscape degradation would decrease environmental heterogeneity and change predominant physical-habitat types, which in turn would decrease the functional diversity and alter the functional identity of fish assemblages. We sampled fish from 40 streams in the Upper Paraná River basin, and assessed catchment and instream conditions. We then conducted an ecomorphological analysis to functionally characterize all species (36) and quantify different facets of the functional structure of assemblages. We detected multiple pathways of the impacts from landscape changes on the fish assemblages. Catchment degradation reduced the stream-bed complexity and the heterogeneity of canopy shading, decreasing assemblage functional specialization and divergence. Landscape changes also reduced the water volume and the amount of large rocks in streams, resulting in decreased abundances of species with large bodies and with morphological traits that favor swimming in the water column. We conclude that land-use intensification caused significant changes in aquatic biodiversity in the Cerrado, reinforcing the need to pay special attention to this global hotspot.

Influence of Canopy Cover on Surface Temperature

Trees affect the microclimate, which influences thermal comfort and ecosystem processes. This study investigated the influence of the canopy cover on daily maximum and minimum temperatures. The data are from a collaborative database, and each measurement consists of the minimum and maximum temperatures under the canopy and in an open adjacent area over a 24-hour period. Paired sample t-tests indicated that the canopy decreased the maximum and minimum daily temperatures and narrowed the daily temperature range. Multiple regression showed that the canopy cover percentage decreased the maximum daily temperatures, and this effect was greater in rural areas than in urbanized areas. Another multiple regression indicated that the canopy cover percentage and the distance to the edge of the canopy decreased the daily temperature range. An independent sample t-test also indicated that the effect of the canopy on the daily temperature range was higher in rural areas when analysed by parametric and non-parametric tests but not when measured by a robust test. Other independent sample t-tests indicated that the distance from a light source also decreased the canopy effect on the minimum daily temperature and the daily temperature range. The main plausible underlying processes include the canopy shade and wind insulation, litter insulation of the ground surface, heat pumps through evapotranspiration and lateral heat fluxes from light bulbs and other anthropogenic sources, especially in urbanized areas. These results provide a greater understanding of the effects of arborization in rural and urban ecosystems, as well as their respective benefits to human communities.

Assessing the effects of urban street trees on building cooling energy needs: The role of foliage density and planting pattern

This study presents an one-way coupling approach between the ENVI-met microclimate model and the EnergyPlus building energy simulation program, to assess the effect of the urban greenery on the improvement of the buildings’ cooling energy needs, in a dense urban area in Thessaloniki, Greece. Three commonly encountered urban tree species with different foliage densities are analyzed, whereas 2 different planting patterns are also considered. The obtained results indicate that the potential of trees on cooling the ambient air temperature and regulating the buildings cooling energy needs is mainly attributed to the radiative shading and the respective reduction of the solar heat gains of the exposed building façades. Moreover, the reduction of the building’s cooling energy demand due to the addition of trees is directly related to their foliage density and their planting pattern. The higher energy savings up to 54 % have been achieved when the trees formed a continuous shading canopy and for the Leaf Area Density of 2.5 m2/m3. Yet, the cooling potential of street trees has been found rather minor when they were not tall enough to shade the biggest part of the outer building façade.

Effects of Light and Autotoxicity on the Reproduction of Bidens pilosa L.: From Laboratory to the Field

In Taiwan, the good agricultural practices for Bidens pilosa L. (Cobbler’s pegs) had been established due to its pharmacology application. However, the reproduction of this species that may cause phytotoxicity to the subsequent crops has not been investigated extensively. We hypothesized that both the phytotoxicity and canopy shading conditions that were altered by agricultural practices might affect its seed reproduction. Three experiments from laboratory, pot and field were conducted under different light treatments and residue application rates to evaluate the light requirement and phytotoxicity on the germination of Cobbler’s pegs. The results showed that the germination in the laboratory, dark treatments was higher than that of light treatment while it was inhibited in the darkness in the pot experiments (24% of the light treatments). Moreover, some seeds in the pot experiments germinated in the far-red light (FR) pretreated dark treatments. This observation indicated that the germination response of the investigated plant might be a very low fluence response (VLFR). Results also showed that the autotoxicity enhanced the germination reduction in the FR pretreated dark treatment while increasing the residues buried in the field. Accordingly, both autotoxicity and canopy shading may inhibit the reproduction of Cobbler’s pegs, but the application method needs further study.

Pertumbuhan Widelia (Wedelia trilobata (L) Hitchc) pada Tingkat Naungan Berbeda di Jalur Hijau Kota Yogyakarta

Widelia plant (Wedelia trilobata (L) Hitchc) is a spreading herb from the Asterase family that potentially can be used as a ground cover in the roadside greenery because this plant has a faster growing rate and has aesthetic values in both leaves and flowers. The aim of this study was to observe the microclimate of the roadside greenery and the vegetative growth of widelia at three levels of the tree canopy shades in the collector and local roads of Yogyakarta City. The experiment was carried out using an inter-site design (oversite) consisting of two factors, namely road factors (collector roads and local roads) and levels of shade canopy (full > 50%, moderate 20–50% and no shade 0%). The results of the analysis of variance did not show any significant differences on the microclimate and widelia growth parameters on the collector or local roads. The wind speed, noise, and number of vehicles on the collector road showed the higher number compared to those on the local road. The results of analysis of variance in the three levels of tree canopy shade also showed significant differences in microclimate and widelia growth parameters. The lowest light intensity, air temperature, humidity, soil temperature, soil moisture, stolon length, number of leaves, number of shoots, number of segments, and dry weight plants were found in full shade level (> 50%). All observation variables did not show any significant interaction effect between the two types of roads and the three levels of tree shades.
 Keywords: canopy shade, microclimate, roadside greenery, widelia (Wedelia trilobata (L) Hitchc), Yogyakarta

Infestation of mistletoe Dendrophthoe pentandra (L.)Miq on various canopy shading and plants diversity in Purwodadi Botanic Garden: A study on medicinal plant Cassia fistula L.

Mistletoe Dendrophthoe pentandra (L.)Miq is a parasitic plant commonly found parasitizing and infesting medicinal plants such as Cassia fistula L. This research aimed to investigate the infestation of D. pentandra on C. fistula on various trees canopy shading, infested host number and plant diversity. Study was conducted in Purwodadi Botanic Garden which located in Purwodadi, Pasuruan, East-Java during January-March 2020. Data Collection was conducted by explorative and descriptive methods in each block locations in the garden. Sampling plots were determined by purposive sampling method using 20x20 m per plot in each block where the tree of C. fistula found. The canopy shading was categorized as : open (4) = light interception more than 90%, rather open (3) = light interception = 60-90%, rather shady (2) = light interception 30-60%, shady (1) (light interception less than 30%). The result showed that the infestation of D. pentandra was affected significanly by the plant canopy shading and the infested host number in the blocks. The highest infestation of misletoe D. pentandra on C. fistula was found in the open canopy and the highest infested host plants in the block III.D with the parasite number 13 per plant. The tree plant diversity in the blocks tend to have negative correlation to the infestation of D. pentandra on C. fistula with r = -0.18.

Photochemical responses to light in sun and shade leaves of Theobroma cacao L. (West African Amelonado)

Theobroma cacao is a tropical understory tree that is traditionally grown in an agroforestry system under a shade canopy; but is increasingly being grown in an orchard system with limited shade or no shade. This study investigated the light response of sun and shade leaves from mature trees of one of the most cultivated cacao accession (West African Amelonado), grown under full sun conditions. Chlorophyll fluorescence was used to measure Fv/Fm, and to generate light response curves for photosynthetic and non-photosynthetic quenching parameters. The light response curves indicated an increased capacity for photosynthesis in the sun leaves however the Fv/Fm and NPQ data showed that the sun leaves were subject to photoinhibition. Biochemical assays were used to compare sun and shade leaves for photosynthetic pigment content and a range of parameters related to reactive oxygen species scavenging and cellular damage. The sun and shade leaves demonstrated typical pigment plasticity however the chlorophyll carotenoid ratio was low for both types of leaves. There was no observed plasticity in superoxide dismutase activity between the sun and shade leaves however the plant was able to respond to the increased photosyntheically active radiation by increasing the activity of ascorbate peroxidase and to a lesser extent catalase. Increased electrolyte leakage in the sun leaves however suggests that the ability to mitigate reactive oxygen species was limited. The results point to limitations in the ability of currently cultivated cacao to acclimate to full sun conditions.