Shade Levels Research Articles

Early Growth Characterization and C:N:P Stoichiometry in Firmiana simplex Seedlings in Response to Shade and Soil Types

Light and soil environments have extensive heterogeneity for many plants species affecting plant growth, reproduction, and distribution. However, the interaction effects of these two factors on the ecophysiological traits and adaptive strategy of plants remain largely unclear. In the present study, we set four shading levels and three soil types to investigate the effects of shade and soil type on seedlings growth, C:N:P stoichiometry responses, and nutrient use efficiency in Firmiana simplex (F. simplex). The maximum of total biomass was observed in acid purple soil under 75% shade, with a maximum difference of 3.6 times. With the increase in shading intensity, C content in the root, stem, and leaf reached maximum value under 75% shade. However, C content in the root and N content in the stem reached a maximum value of 420.6 g·kg−1 and 13.7 g·kg−1 in acid purple soil, respectively. With the increase in shading intensity, the total C and N accumulation showed a trend of progressive increase and then decrease, reaching the maximum value of 346.2 mg and 10.7 mg under 75% shade, respectively. The N:P ratios of various organ ranged from 3.1 to 11.9 in acid purple soil and red soil, indicating that the seedlings growth was restricted by nitrogen. We concluded that the interactions of shade and soil types might adjust the C:N:P stoichiometry and influence the dynamic balance between nutrients and organs in F. simplex seedlings.

The Use of Mulch and Shading Improves the Survival of Sclerophyllous Species Established in Island Plots in Central Chile

Climate change is threatening the restoration efforts in Mediterranean ecosystems, and there is still little knowledge about the responses of some sclerophyllous species to plant management techniques. This study assessed the effects of the planting date, use of mulch, and controlling light levels on the early survival and growth of sclerophyllous species established in island plots. A factorial design was installed in the Metropolitan Region of central Chile, with a treatment combination that included three planting dates (January: midsummer, April: autumn, and June: winter), three light levels (full sun exposed (T0), shaded at 35% (T35), and shaded at 70% (T70)), and two mulch levels (no mulch versus mulch application). Additionally, we tested the species effects within the island plot. We measured survival, as well as plant diameter and height increments, 1 year after establishment. Each island plot contained three seedlings of Acacia caven Mol., two of Quillaja saponaria Mol., two of Maytenus boaria Mol., one of Schinus polygamus (Cav.) Cabrera, and one of Cryptocarya alba (Mol.) Losser. We found a significant main effect for all the factors assessed. Despite the high mortality in the trial, survival was increased around fourfold by planting in winter, using mulch, or using either of the shading levels. At the species level, average survival ranged from 7% for C. alba to 27% for S. polygamous. To increase plant survival in the restoration of this ecosystem, it is necessary to intensify the management techniques and the use of these types of eco-technologies; if not, the restoration may fail.

Biology, Germination Ecology, and Shade Tolerance of Alkaliweed (Cressa truxillensis) and Its Response to Common Postemergence Herbicides.

Alkaliweed (Cressa truxillensis) is a native perennial plant of the western USA and in California, they are found primarily in saline and alkaline soils. Lately, it has been observed in Central Valley pistachio, olive, and almond orchards as a problematic species. Very little information is available on the effect of environmental factors on germination, shade tolerance, and the response of this species to herbicides. Therefore, studies were conducted to assess the effect of environmental factors (water potential, salinity, and pH) on seed germination, the influence of shade (30% shade 70% shade, and no shade) on aboveground growth, and the response of alkaliweed to common registered post-emergent herbicides. Results showed that the seeds were moderately tolerant to drought but highly adapted to salinity and pH as germination occurred up to an electrical conductivity level of 20 dS m-1 and pH range of 5 to 9. Both shade levels reduced aboveground growth and formation of reproductive structures. None of the postemergence herbicides provided adequate control of the plants. Therefore, an integrated management plan needs to be developed for alkaliweed control in Central Valley orchards.

Physiological, growth, yield, and quality responses of hot pepper due to shade level

ABSTRACT High temperatures, high relative humidity, and frequent rainfall limit productivity and quality of red chili pepper (Capsicum annuum L) with 30,000 to 50,000 Scoville units. Growers in greenhouses use shading screens to limit incidence radiation in order to avoid the issue of too high temperatures and high radiation. A pot experiment was conducted to assess growth, physiology, yield, and quality responses of three pepper varieties under four shade levels. The combined effects of shade level and pepper variety affected days to 50% flowering, days to breaker stage, plant height, node number, internode length, branch number, relative growth rate, leaf number, leaf area, transpiration rate, photosynthesis rate, stomatal conductance, leaf temperature, fruit length, fruit weight per plant, total soluble solids, marketable fruit yield, cull fruit yield, total fresh fruit yield, and total dry fruit yield. Shade levels from 25% to 50% positively affected chlorophyll fluorescence, chlorophyll content, stomatal conductance, transpiration rate, fruit yield, and quality parameters; above this shade level, these parameters were negatively affected in all pepper varieties. Light and shade influenced growth, physiology, yield, and quality of hot peppers. The hot pepper variety Mareko Fana, grown under 25% shade, improved its productivity and pod quality.

Genotypic Variation of Purple Rice in Response to Shading in Yield, Anthocyanin Content, and Gene Expression.

Purple rice (Oryza sativa L.) contains anthocyanin, which acts as an antioxidant and functional food for humans. The levels of anthocyanin growth and production in rice are mainly controlled by the availability of light. However, shade can affect anthocyanin biosynthesis genes. Therefore, the objective of this study was to determine the yield and anthocyanin content among four purple rice varieties, which provide the difference in colors of purple and green leaves. This study also evaluated gene expression affected by shading treatment to understand the relation of grain anthocyanin and expression level. This research was conducted using a split plot design using four levels of shading (levels of shading from anthesis to maturity) with three replications, no shading, 30% shading, 50% shading, and 70% shading, as the main plots and purple rice varieties as subplots, KJ CMU-107, K2, K4, and KDK10, from anthesis to maturity. Shading significantly decreased yield and yield components, but increased grain anthocyanin content. Nonetheless, the response of yield and grain anthocyanin content to shading did not show a significant different between purple and green leaf varieties. In addition, the level of OsDFR gene expression was different depending on the shading level in four rice varieties. The OsDFR gene presented the highest expression at shading levels of 30% for K4 and 50% for KDK10, while the expression of the OsDFR gene was not detected in the purple rice varieties with green leaves (KJ CMU-107 and K2). The response of grain anthocyanin and gene expression of OsDFR to light treatment did not show significantly differences between the purple and green leaf varieties, suggesting that the appearance of anthocyanin in leaves might be not related to anthocyanin synthesis in the grain. Taken together, the results suggest that some purple rice varieties were more suitable for planting under low light intensity based on a lower level of grain yield loss, strong shade tolerance, and high anthocyanin content in leaf and grain pericarp. However, it is necessary to explore the effects of light intensity on genes and intermediates in the anthocyanin synthesis pathway for further study.

Assessing the performance of façade-integrated transparent photovoltaic panels for daylight and energy generation in high rise buildings of hot & dry climate

Indian cities are witnessing a boom in the growth of high-rise buildings to accommodate the ever-intensifying population. The modern trend of applying glass on the façades of tall buildings holds a threat due to Indian climates. Though it allows the daylight, reduces the artificial lighting, and provides a good view, the heat gained through the glass façades increases a building’s energy consumption. Therefore, an innovative, advanced strategy is required that replaces the glass with alternatives which can potentially minimize the energy demands either by controlling the heat gain or producing the electricity by itself, to match the demand. Transparent photovoltaic facades can ideally solve this purpose, as it allows the daylight and are multi-functional in nature. It produces electricity and fulfils several other tasks of solar protection and glare protection. But, the presence of solar cells may cause undesirable shading or low illuminance levels; hence, it is important to comprehensively assess the daylight performance and also calculate its energy performance. The aim of the current research paper is to determine the effectiveness of integrating the transparent photovoltaic panels over window/glass façades of daytime-occupied high-rise buildings in a Hot & dry climate and the form configurations required to achieve a considerable amount of energy on-site, without affecting the quantity of daylight. In this study, the performance of the amorphous silicon (a-Si) PV window, with 26.7% visibility, was evaluated through simulation using Rhino+Honeybee software over different building sizes & aspect ratios. The results showed that there was a gradual decline in the energy intensity with increase in length and the energy intensity got increased with an increase in floor height. The form with a high aspect ratio had the highest EPI of 228kwh/m2/year. Further, the form with the least aspect ratio achieved a better daylight performance. The findings of this research are potentially valuable for building designers and decision-makers to foresee the behaviour pattern of BIPV facades in energy generation, while affirming a comfortable and luminous environment.

Comparison of Growth and Leaf Color Quality of <italic>Mesembryanthemum cordifolium</italic> f. <italic>variegata</italic> as Affected by Shading Levels

Background and objective: Mesembryanthemum cordifolium is a plant belonging to the Aizoaceae family and is native to South Africa and Namibia. As a CAM plant, M. cordifolium exhibits strong resistance to drought stress and can be utilized for the removal of soil salinity and heavy metals. Furthermore, it is an important medicinal crop with anti-inflammatory and antidepressant effects. However, despite its potential benefits, research on the optimal growth environment for M. cordifolium remains scarce.Methods: Therefore, this study selected M. cordifolium f. variegata with high ornamental value as the experimental plant and compared the effects of different shading levels on the growth and leaf color quality of variegated baby sun rose (M. cordifolium f. variegata). Six shading levels (0, 35, 45, 60, 75, and 99%, respectively) were designed using polyethylene (PE) shading films.Results: The results showed that the shoot height, shoot width, dry weight, and chlorophyll content (SPAD units) were highest under the 60% shading level, while leaf length, leaf width, and fresh weight were highest under the 75% shading level. On the other hand, growth was relatively lower under the 0% shading level, which suggests that M. cordifolium f. variegata prefers shade over direct sunlight. On the contrary, M. cordifolium f. variegata showed growth even under the 99% shading level, proving to have strong shade tolerance, but the leaf color quality was lowerst.Conclusion: In conclusion, to significantly increase the size and biomass of plants and improve leaf color quality when cultivating M. cordifolium f. variegata under shading treatment, it is recommended to cultivate it under 60-75% shading levels.

An Analysis of the Growth and Photosynthetic Responses of Potted <italic>Veronica pusanensis</italic> Y.N.Lee according to the Shading Levels

Background and objective: Veronica pusanensis, an endemic species of South Korea belonging to the Plantaginaceae family, is found in Busan, South Korea. Due to its high ornamental value, it is expected to be utilized as a flower crop. However, currently it is an endangered species with its habitats being destroyed and reduced.Methods: Therefore, in this study, we analyzed the growth and photosynthetic responses of potted plants of V. pusanensis under different shading levels to enable mass production. Polyethylene (PE) shading films were selected as the shading material, and shading levels were designed at 0, 35, 45, 60, 75, and 99%, respectively.Results: Results showed that shoot height, shoot width, ground cover, leaf length, leaf width, shoot fresh and dry weight, chlorophyll content (SPAD units), and chlorophyll fluorescence parameters Fv/Fm and PIABS were highest under the 35% shading level. This indicates that it is relatively more desirable to grow V. pusanensis in shade culture compared to under direct sunlight. Meanwhile, root fresh weight and dry weight were highest under the 0% shading level.Conclusion: Therefore, it is recommended to grow V. pusanensis under direct sunlight to significantly increase root biomass when the purpose is to facilitate rootage when transplanting plants for habitat restoration. On the other hand, for the cultivation of V. pusanensis as an ornamental flower crop, it is recommended to grow the plants under the 35% shading level to significantly increase plant sizes and maintain ensure the proper functioning of photosynthetic responses in photosystem II (PSII).

PRODUCTION OF AÇAÍ SEEDLINGS UNDER DIFFERENT SHADE LEVELS AND CONTROLLED RELEASE FERTILIZER

This study aimed to evaluate the production and quality of açaí seedlings regarding the presence and absence of controlled-release fertilization under different shading levels. The study was conducted at the experimental field of Embrapa - Acre, using a completely randomized design in a 4 x 4 factorial arrangement. The factors included four evaluation periods (60, 120, 180, and 240 days after transplanting) and four shading environments (20%, 30%, 50%, and 75%), along with the presence or absence of controlled-release fertilization. The following variables were analyzed: plant height, stem diameter, number of leaves, dry mass of leaves, stem, root, and total dry mass, as well as the seedling quality index and foliar levels of macro and micronutrients. The growth and development of açaí seedlings are influenced by the evaluation periods, shade environments, and the use of fertilization. Fertilization with controlled-release fertilizer and environments with30% and 50% shading improved the quality of açaí palm seedlings.

Influence of shade levels on morpho-physiological characteristics of potted spathiphyllum

The intensity of the shade is a critical factor in the production of potted spathiphyllum. Plants were grown in various levels of green coloured shade net to assess the growth response regarding vegetative, flowering, and physiological characteristics. The results showed that under 75 % shade, spathiphyllum plants exhibited the most significant plant spread, petiole girth, leaf thickness, leaf number, and leaf length. Likewise, spathe characters such as length, width, diameter, and the number of blooms were recorded highest at 75 % shade level. Similarly, the fresh weight and dried weight of the leaves were also found to be significant. Foliage chlorophyll content and foliage longevity increased linearly with increasing shade. Shade levels improved the spathiphyllum’s foliage colour, an essential characteristic of indoor plants. It is concluded that using shade nets with a shade intensity of 75% would result in better growth and production of potted spathiphyllum, allowing farmers to earn more income.

Effect of Shading Percentage and Potassium Dosages on Growth and Yield of Cutleaf Groundcherry (Physalis angulata L.)

Cutleaf groundcherry is a medicinal herbaceous plant that has not been widely cultivated. Adjustment to the light intensities supported by the fulfillment of essential macro-nutrient underlies the agronomic consideration for cropping system determination. The study aimed to examine the growth and yield of cutleaf groundcherry grown under shade nets of various shading percentages and potassium application at different dosages. A split-plot design was used for this pot experiment repeated three times. The main plot was the shading percentages (0, 25, 50 and 75), while potassium dosages (0, 60, 120 and 180 kg ha<sup>-1</sup>) were the subplot. The result showed that several growth variables were affected by the interaction between shading percentages and potassium dosage, whereas yield variables were not. Under the high level of shading, leaf number (41% to 50%), leaf area (28% to 50%), and shoot dry weight (70% to 85%) were reduced at all potassium dosages. Potassium dosage at 120 kg ha<sup>-1</sup> was required to achieve better growth under full sun or soft shading. Shading at 50% and upper significantly decreased fruit production by 30% lower fruit number, 50% to 80% lower fruit weight, and 15% lower total soluble solids (TSS). In addition, potassium fertilizer at 120 kg K<sub>2</sub>O ha<sup>-1 </sup>improved fruit weight but did not affect TSS. It can be concluded that cutleaf groundcherry is able to grow well under high intensity of light and need an adequate supply of potassium to improve growth, yield and fruit quality.

Regional climate affects habitat preferences and thermal sums required for development of the Eurasian spruce bark beetle, Ips typographus

In recent years, the outbreaks of the Eurasian spruce bark beetle (Ips typographus) have become more frequent and severe, while temperatures have been rising. Our understanding of the consequences of climate warming can be improved by comparing the performance of I. typographus between geographical regions with different climates. We applied that approach by placing out Norway spruce logs at sites selected along a 1300 km north–south gradient in Sweden to study the effect of regional climate and microclimate on I. typographus. To obtain a microclimatic gradient at each site, we placed the logs at sun-exposed edges and in the shaded inner forest (10 m or 50 m from stand edges). We assessed the probability of colonisation of I. typographus and the thermal sums required for complete development.The species’ habitat preferences differed along the climate gradient including six geographical regions: in cooler regions, a higher proportion of sun-exposed logs was colonised in comparison to the shaded ones, while that difference was much smaller in warmer regions. The thermal sum needed for development tended to increase with warmer regional climate. Seasonal thermal sum exceeded the requirements for development of two generations per year in all three shade levels in the warmest region while in the coldest region two generations were only possible in some of the sun-exposed logs.Outbreaks of I. typographus are more frequent and severe in regions with a warmer climate, and our study reveals two explanations for this: first, I. typographus has more suitable breeding sites in warmer regions, as shaded logs inside the forest offer additional suitable habitat; second, the potential population growth increases with the probability of completing two fully established generations per year. We recommend that after storm-fellings, wind-felled trees are removed before they are colonised by I. typographus to decrease the outbreak risk. The observed difference in habitat preferences between geographical regions implies that, in cooler sites in the north, it is enough to remove recently wind-felled spruces that are sun-exposed, such as along edges, while in the south, also trees in more shaded conditions inside forests are a suitable substrate for I. typographus. In a warming climate, the increased risk and severity of I. typographus outbreaks is a factor making it less attractive to use Norway spruce in forestry.

Cardamom agro-environmental interrelationships analysis in Indian cardamom hills

The rainfall pattern seen in the Indian Cardamom Hills (ICH) has been extremely variable and complicated, with El Niño-Southern Oscillation (ENSO) playing a crucial role in shaping this pattern. In light of this, more investigation is required through improved statistical analysis. During the study period, there was greater variability in rainfall and the frequency of rainy days. About 2,730 mm of rainfall was reported in 2018, while the lowest amount (1168.3 mm) was registered for 2016. The largest decrease in decadal rainfall (>65 mm) was given by the decade 1960–1969, followed by 1980–1989 (>40 mm) and 2010–2019 (>10 mm). In the last 60 years of study, there has been a reduction of rainy days by 5 days in the last decade (2000–2009), but in the following decade (2010–2019), it registered an increasing trend, which is only slightly <2 days. The highest increase in decadal rainy days was observed for the 1970–1979 period. The smallest decadal increase was reported for the last decade (2010–2019). Total sunshine hours were the highest (1527.47) for the lowest rainfall year of 2016, while the lowest value (1,279) was recorded for the highest rainfall year (2021). The rainfall characteristics of ICH are highly influenced by the global ENSO phenomenon, both positively and negatively, depending on the global El Nino and La Nina conditions. Correspondingly, below and above-average rainfall was recorded consecutively for 1963–1973, 2003–2016, and 1970–2002. Higher bright forenoon sun hours occurred only during SWM months, which also reported maximum disease intensity on cardamom. The year 2016 was regarded as a poorly distributed year, with the lowest rainfall and the highest bright afternoon sun hours during the winter and summer months (January-May). Over the last three decades, the production and productivity of cardamom have shown a steady increase along with the ongoing local climatic change. Many of our statistical tests resulted in important information in support of temporal climatic change and variability. Maintaining shade levels is essential to address the adverse effects of increasing surface air temperature coupled with the downward trend of the number of rainy days and elevated soil temperature levels.

A STUDY ON HOW NUTRIENTS AND SHADE AFFECT THE GROWTH OF ANTHURIUM CUT FLOWERS

The effect of shade, growth medium, and their interaction on anthurium cut flower output was investigated using a Factorial totally randomised block design with 3 replications. Three levels of shade (85%, 75%, and 65%) and four combinations of growing media (coco peat + coconut husk, coco peat + brick pieces, coconut husk + brick pieces, red earth + sand (control), and red earth + sand at a ratio of 1:1) were used as main factors in this experiment, with a total of twelve interaction treatments. The per se and interaction impacts of shade and growing medium on the development, physiology, flowering, yield, quality characteristics, and nutrient content of anthurium plants were substantially impacted by the treatments

Influence of Shading and Paclobutrazol Concentrations on Growth and Quality Characters of Three Different Turf Grasses Genera

This study was carried out in Pirmam,, Erbil Governorate - Iraq for two years, from 15 March 2020 to 15 March 2021 in the spring season and from 15 September2020 to 15 September 2021 in the autumn season, to study the responses of three turf grass genera, includingermuda grass (Cynodon dactylon L. var. cd4), Tall fescue grass (Festuca arrundaceae L. var. Barleroy) and Creeping bent grass (Agrostis palustris) cultivated by seeds to two shading levels of 0 and 75% and sprayed with three paclobutrazol concentrations at 0, 750 and 1500 mg. l-1. The experiment was performed by using Randomized Complete Block Design (RCBD) in a split-plot design with three factors and three replications. The results showed that the shading level (0%) led to a significant increase in most studied characters like mowing number, cumulative dry weight of turf grass clipping yield, dry root weight, total chlorophyll and carbohydrate percentage and was superior to those grown under 75% shading. Both levels of shading had no significant effects on color degree and coverage percentage of the used turf grasses. It also showed that foliar spray of paclobutrazol had a significant impact on those traits. The highest values of plant density, mowing number, and cumulative dry weight of clipping yield were recorded when turf grasses were unsprayed with paclobutrazol, while the highest values of color degree, coverage percentage, total chlorophyll content, and carbohydrate percent were obtained when turf grasses were sprayed with 1500 and 750 mg.l-1 of paclobutrazol, respectively. Significant differences were shown among turf grass genera that were grown from seeds in those traits. Agrostise genus was significantly superior to other genera only in plant density, while Festuca genus was significantly superior to other genera in the rest of the other characteristics. As for triple interactions, the highest significant values for most characteristics were found in Festuca genera that were sprayed with 750 and 1500 mg.l-1 concentrations of paclobutrazol and grown in open fields.

Analysis of morphological characters in soybean plants submitted to different levels of artificial shading

Morphological characters of soybean can be influenced by shading which are occasionally caused in plants. Thus, this study aimed to evaluate the effect of different shading levels on epicotyl length, epicotyl diameter and height of soybean plants. The experiments were conducted in a greenhouse. When the plants reached the V2 development stage, measurements were taken of epicotyl length and epicotyl diameter in experiment I (conducted in autumn); and epicotyl length, epicotyl diameter, and plant height in experiments II (spring/summer) and III (summer). Each experiments were conducted in a randomized block design, in subdivided plots, with four repetitions. The plots were composed of four shading levels and the subplots were composed of eight conventional cultivars. Each experimental unit consisted of one plant grown in a 3 dm³ pot filled with soil and organic matter. The three characters evaluated in the experiment presented significant effect for the interaction cultivar x shading x sowing seasons. Epicotyl length, independent of the sowing season, increased as the shading level intensified. Both the shading level and the sowing season influenced the diameter of the epicotyl, in a general way, reducing the diameter as the shading level increased. With increasing shading rate there was an increase in plant height. Moreover, the cultivars formed statistically distinct groups for the three morphological characters evaluated.

Influence of shade on productivity and nutritional value of Urochloa decumbens in silvopastoral systems using different spatial arrangements of eucalyptus cultivars

This study evaluated pasture productivity and nutritional characteristics of Urochloa decumbens in silvopastoral systems (SPS) with different eucalyptus cultivars and spatial arrangements providing differing levels of shade. SPS were arranged to provide 46 % shade (eucalyptus trees arranged in 2 double rows 2 m apart, with trees every 3 m in each row, and 20 m between double rows), 60 % shade (eucalyptus trees arranged in 2 double rows 2 m apart, with trees every 2 m in each row in double rows and 9 m between double rows) and 57 % shade (eucalyptus trees arranged in a single row, with trees every 2 m in the row and 9 m between rows) using eucalyptus cultivars ‘GG100’, ‘I144’ or ‘VM58’. Two full sun pastures treated as managed (soil pH correction and N, P and K fertilizer application) or non-managed (no correction or fertilizer application) were evaluated in addition to the 3 SPS arrangements. Photosynthetically active radiation (PAR) was 1,439 μmol/m2/s in full sun compared with a mean of 715 μmol/m2/s under different SPS arrangements. Leaf area index of U. decumbens was 28 % higher in 46 % shade and lower in all shade arrangements compared with full sun managed pasture. The dry matter yield was 58 % lower in 46 % shade and 86 % lower in 60 % shade compared with full sun managed pasture. The crude protein content in SPS pastures was higher than in the full sun pastures, with higher values in 57 % and 60 % shade. SPS significantly reduced the PAR and forage yield. These results indicate that in systems where the main objective is animal production, spacing between tree rows greater than 20 m should be used to provide sufficient high-quality grass.

Bioprospeksi Bunga Lolipop (Pachystachys lutea Nees) sebagai Sumber Alternatif untuk Produksi Gula

The lollipop plant (Pachystachys lutea Nees) has been known as an ornamental plant species that originated from the South America region. In Indonesia, some local children claim that the nectar of this flower has a very sweet flavor. This fact has inspired this short bioprospecting study of the lollipop plant with aim to discover its nectar as a potential alternative sugar source. The study was conducted in Bandung, West Java, Indonesia. Four lollipop plants from three different shading level (one plant in full shade andpartial shade, and two plant in full sun exposure) were sampled as many as five flowers from each plant and their nectar droplets, measured using brix refractometer, and also compared with sweet corn seeds (Zea mays L.) and sugarcane stems (Saccharum officinarum L.). The data was then validated for its significance using t-Tests. The result shows that the lollipop plant grown in partial shade has the highest brix percentage (27.00±1.02%) compared to the rest and is significantly different statistically. The brix percentage of all samples combined for this lollipop plant (25.56±0.42%) also surpassed the sugarcane (15.33±0.36%) and sweet corn (12.67±0.47%) and was significantly different statistically.

Drying, more than warming, alters ecosystem functioning in streams with different energy pathways

Abstract Empirical evidence and theory suggest that climate warming and an increase in the frequency and duration of drying events will alter the metabolic balance of freshwater ecosystems. However, the impacts of climate change on ecosystem metabolism may depend on whether energy inputs are of autochthonous or allochthonous origin. To date, few studies have examined how warming and drying may interact to alter stream metabolism, much less how their impacts may depend on the energy‐base of the food web. To address this research gap, we conducted a multi‐factorial experiment using outdoor mesocosms to investigate the individual and synergistic effects of warming and drought on metabolic processes in stream mesocosms with green (algal‐based) vs. mixed (algal‐ and detritus‐based) vs. brown (detritus‐based) energy pathways. We set up 48 mesocosms with one of three different levels of shade and leaf litter input combinations to create mesocosms with different primary energy channels. In addition, we warmed half of the mesocosms by ~2–3°C. We assessed changes in ecosystem respiration (ER), gross primary production (GPP), net ecosystem production (NEP) and organic matter biomass in warmed and ambient temperature mesocosms before a 24 day drying event and after rewetting. Surprisingly, experimental warming had little effect on metabolic processes. Drying, however, led to decreased rates of ER and GPP and led to an overall reduction in NEP. Although the effects of drying were similar across energy channel treatments, reductions in ER and GPP were primarily driven by decreases in biomass of benthic and filamentous algae. Overall, we demonstrate that drying led to lower rates of NEP in mesocosms regardless of energy inputs. While warming showed little effect in our study, our results suggest that an increase in the frequency of stream drying events could greatly alter the metabolic balance of many aquatic ecosystems. Read the free Plain Language Summary for this article on the Journal blog.

Assessing the Contributions of Urban Green Space Indices and Spatial Structure in Mitigating Urban Thermal Environment

Urban green space takes a dominant role in alleviating the urban heat island (UHI) effect. Most investigations into the effects of cooling factors from urban green spaces on the UHI have evaluated the correlation between each factor and land surface temperature (LST) separately, and the contribution weights of various typical cooling factors in mitigating the thermal environment have rarely been analyzed. For this research, three periods of Landsat 8 data captured between 2014 and 2018 of Xuzhou during the summer and autumn seasons were selected along with corresponding meteorological and flux measurements. The mono-window method was employed to retrieve LST. Based on the characteristics of the vegetation and spatial features of the green space, eight factors related to green space were selected and computed, consisting of three indices that measure vegetation and five metrics that evaluate landscape patterns: vegetation density (VD), evapotranspiration (ET), green space shading degree (GSSD), patch area ratio (PLAND), largest patch index (LPI), patch natural connectivity (COHESION), patch aggregation (AI), and patch mean shape index distribution (SHPAE_MN). Linear regression and bivariate spatial autocorrelation analyses between each green space factor and LST showed that there were significant negative linear and spatial correlations between all factors and LST, which proved that the eight factors were all cooling factors. In addition, LST was strongly correlated with all factors (|r| > 0.5) except for SHPAE_MN, which was moderately correlated (0.3 < |r| < 0.5). Based on this, two principal components were extracted by applying principal component analysis with all standardized green space factors as the original variables. To determine the contribution weight of each green space factor in mitigating the urban heat island (UHI) effect, we multiplied the influence coefficient matrix of the initial variables with the standardized multiple linear regression coefficients between the two principal component variables and LST. The final results indicated that the vegetation indices of green space contribute more to the alleviation of the UHI than its landscape pattern metrics, and the contribution weights are ranked as VD ≥ ET > GSSD > PLAND ≈ LPI > COHESION > AI > SHAPE_MN. Our study suggests that increasing vegetation density is preferred in urban planning to mitigate urban thermal environment, and increasing broadleaf forests with high evapotranspiration and shade levels in urban greening is also an effective way to reduce ambient temperature. For urban green space planning, a priority is to multiply the regional green space proportion or the area of largest patches. Second, improving the connectivity or aggregation among patches of green space can enhance their ability to cool the surrounding environment. Altering the green space spatial shape is likely the least significant factor to consider.