Moderate Shade Research Articles

Effect of Interactions between Phosphorus and Light Intensity on Metabolite Compositions in Tea Cultivar Longjing43

Light intensity influences energy production by increasing photosynthetic carbon, while phosphorus plays an important role in forming the complex nucleic acid structure for the regulation of protein synthesis. These two factors contribute to gene expression, metabolism, and plant growth regulation. In particular, shading is an effective agronomic practice and is widely used to improve the quality of green tea. Genotypic differences between tea cultivars have been observed as a metabolic response to phosphorus deficiency. However, little is known about how the phosphorus supply mediates the effect of shading on metabolites and how plant cultivar gene expression affects green tea quality. We elucidated the responses of the green tea cultivar Longjing43 under three light intensity levels and two levels of phosphorus supply based on a metabolomic analysis by GC×GC-TOF/MS (Two-dimensional Gas Chromatography coupled to Time-of-Flight Mass Spectrometry) and UPLC-Q-TOF/MS (Ultra-Performance Liquid Chromatography-Quadrupole-Time of Flight Mass Spectrometry), a targeted analysis by HPLC (High Performance Liquid Chromatography), and a gene expression analysis by qRT-PCR. In young shoots, the phosphorus concentration increased in line with the phosphate supply, and elevated light intensities were positively correlated with catechins, especially with epigallocatechin of Longjing43. Moreover, when the phosphorus concentration was sufficient, total amino acids in young shoots were enhanced by moderate shading which did not occur under phosphorus deprivation. By metabolomic analysis, phenylalanine, tyrosine, and tryptophan biosynthesis (PTT) were enriched due to light and phosphorus effects. Under shaded conditions, SPX2 (Pi transport, stress, sensing, and signaling), SWEET3 (bidirectional sugar transporter), AAP (amino acid permeases), and GSTb (glutathione S-transferase b) shared the same analogous correlations with primary and secondary metabolite pathways. Taken together, phosphorus status is a crucial factor when shading is applied to increase green tea quality.

Responses of the growth, photosynthetic characteristics, endogenous hormones and antioxidant activity of Carpinus betulus L. seedlings to different light intensities.

Light is an important ecological factor that affects plant growth, survival and distribution. Carpinus betulus L. is native to central Europe and is used as an ornamental plant with strong adaptability. It is an important tree species for landscaping and timber use. What's more, the antioxidant- and anticancer-related properties of C. betulus leaf extracts are remarkable, that make it a possible raw material for medicine. Light intensity is an important environmental factor affecting the growth and physicochemical changes of C. betulus, but the mechanism of its effect on this species still remains unknown. In this study, the growth, photosynthetic characteristics, endogenous hormones and antioxidant activity responses of C. betulus seedlings to four light intensity gradients (T0: normal light; T1: 75%; T2: 50%; T3: 25% of normal light) were studied after 60 days of shading treatments. The results showed a significant effect of low light intensity on the values of the growth and physiological parameters of C. betulus. The low light intensity caused the inhibition of plant biomass accumulation and the degradation of photosynthetic capacity and stomatal behavior and aggravated the cell membrane lipid peroxidation. However, the plant height growth, leaf area, specific leaf area, photosynthetic pigment content, and contents of GA3 and ABA of C. betulus increased with decreasing light intensity. We found that C. betulus can tolerate mild (T1) and moderate (T2) shading stress by developing photoprotective mechanisms and maintaining relatively high concentrations of organic osmolytes and high antioxidant enzyme activities (superoxide dismutase, peroxidase, catalase and ascorbate peroxidase), but the ability of C. betulus to synthesize osmotic substances and enzymatic antioxidants was impaired under severe shading conditions (T3). Our results suggest that C. betulus can make effective use of low light resources by adjusting its morphology, material distribution, photosynthetic rate and antioxidant enzyme system in suitable low-light environments (50%~75% of normal light); however, light intensity levels that are too low (25% of normal light) will have adverse effects on plant growth. The results of this study provide not only new insights into the response mechanisms of C. betulus to light intensity but also a scientific basis for the cultivation and application of C. betulus in China.

Shade and Altitude Implications on the Physical and Chemical Attributes of Green Coffee Beans from Gorongosa Mountain, Mozambique

Coffea arabica L. is as a tropical crop that can be grown under monocrop or agroforestry (AFS) systems, usually at altitudes greater than 600 m, with suitable environmental conditions to bean quality. This study aimed to assess the effect of altitude (650, 825, and 935 m) and light conditions (deep shade—DS, and moderate shade—MS provided by native trees, and full Sun—FS) on the physical and chemical attributes of green coffee beans produced in the Gorongosa Mountain. Regardless of altitude, light conditions (mainly MS and FS) scarcely affected most of the studied physical and chemical attributes. Among the few exceptions in physical attributes, bean mass tended to lower values under FS in all three altitudes, whereas bean density increased under FS at 650 m. As regards the chemical compound contents, sporadic changes were found. The rises in trigonelline (MS and FS at 935 m), soluble sugars (FS at 935 m), and the decline in p-coumaric acid (MS and FS at 825 m), may indicate an improved sensory profile, but the rise in FQAs (FS at 825 m) could have a negative impact. These results highlight a relevant uncertainty of the quality changes of the obtained bean. Altitude (from 650 to 935 m) extended the fruit maturation period by four weeks, and altered a larger number of bean attributes. Among physical traits, the average sieve (consistent tendency), bean commercial homogeneity, mass, and density increased at 935 m, whereas the bean became less yellowish and brighter at 825 and 935 m (b*, C* colour attributes), pointing to good bean trade quality, usually as compared with beans from 650 m. Furthermore, at 935 m trigonelline and 5-CQA (MS and FS) increased, whereas FQAs and diCQAs isomers declined (in all light conditions). Altogether, these changes likely contributed to improve the sensory cup quality. Caffeine and p-coumaric acid showed mostly inconsistent variations. Overall, light conditions (FS, MS, or DS) did not greatly and consistently altered bean physical and chemical attributes, whereas altitude (likely associated with lower temperature, greater water availability (rainfall/fog), and extended maturation period) was a major driver for bean changes and improved quality.

English

To investigate the ecological, yield, physiological, and biochemical index of cultivated pinellia under different shade conditions and to analyze the influence of light intensity on Pinellia ternata’s ecological and physiological characteristics, our experiment employed four varieties of pinellia, Changde pinellia, Yuanling pinellia, Ziyang pinellia, and Bijie pinellia, as experiment materials, planted them under equivalent growing conditions, and placed them under different shade conditions (shade net settings of 0%, 25%, 50%, and 75% shade). The present study sought to determine the index changes of pinellia, including their morphology, photosynthesis, antioxidant enzyme activity, and yield, over a 100-day growth period. The results under 25% shade, compared with full light, revealed the following: pinellia plants reached heights of up to 20.04 cm, an increase of 43.35%; the maximum leaf area was 16.15 cm2, an increase of 34.78%; and the fresh weight of pinellia tubers decreased to varying degrees. Under shade treatment, the content of chlorophyll in pinellia leaves increased, the content of soluble protein and malondialdehyde decreased, and the activities of three antioxidant enzymes increased; these changes were overall consistent with the typical characteristics of shade plants, and the adaptability of pinellia to different shade conditions varied considerably. Moderate shade (25%–50% shade) could improve the physiological and ecological indicators of pinellia and reduce the threat of intense light exposure, but it would also reduce the tuber yield to varying extents

Reproductive tradeoffs in a perennial crop: Exploring the mechanisms of coffee alternate bearing in relation to farm management

Like many perennial crops, coffee exhibits alternate bearing, a pattern of reproduction in which high-yielding years are followed by low-yielding ones. Alternate bearing threatens farmer livelihoods, yet little is known about the underlying mechanisms in coffee or the potential for farm management to mitigate it. The resource budget model, an ecological theory positing endogenous resource tradeoffs as the driver of reproductive variability, could help fill this gap. On three coffee farms in Santa María de Dota, Costa Rica, we manipulated relative fruit load, fertilizer levels, and shade cover to test whether the model’s core assumptions (i.e., that fruiting depletes resources and limits investment in subsequent reproduction) can elucidate patterns of alternate bearing in coffee, and to assess whether these patterns are impacted by farm management practices. Coffee plants exhibited within-year and between-year tradeoffs of a high fruit load that scaled from decreased bean size during the same season to fewer fruited nodes and fruits per node in both old and new cohorts of branches during the subsequent season. Stem nitrogen concentration was also depleted in response to high fruit loads and recovered during the subsequent season of low fruiting. The findings provide novel evidence that tradeoffs of a high fruit load are manifested in several reproductive traits at both the branch- and plant-level and offer initial support for the resource budget model in the system. While both moderate shade and increased fertilizer levels tended to improve reproductive traits, a lack of interactive effects between either management treatment and the relative fruit load treatment suggests that they do little to mitigate the reproductive tradeoffs underlying alternate bearing.

Soybean performance under moisture limitation in a temperate tree-based intercropping system

CONTEXTTree-based intercropping (TBI) systems show promise in reducing the vulnerability of field crops to increasing water stress. TBI can generate several above- and belowground interactions between trees and crops. These interactions remain poorly documented, especially in the context of moisture limitation. OBJECTIVEThe objective of this study was to determine the performance of soybean within a TBI system under moisture limitation. We hypothesized that TBI generates both positive (near the alleyway centre) and negative (near the trees) effects on soybean performance and that these effects are accentuated when moisture availability decreases. METHODSA partial rainfall interception treatment (50% of the soil surface) in a soybean crop (stages R1 to R7) was installed for two years (2018 and 2019) in a TBI (50 trees/ha planted in 2012) in southern Quebec. TBI was composed of hybrid poplars (Populus deltoides × P. nigra) and different high-value hardwood species that were planted alternately within rows. A tree root-pruning treatment was also applied to understand belowground effects of tree roots on soybean growth under moisture limitation. Various microclimatic (light availability, wind speed and soil moisture) and soybean performance variables (leaf traits, 100-grain weight and yield) were measured at four distances from the tree row (4, 12 and 20 m, and control). RESULTS AND CONCLUSIONSRainfall exclusion decreased soil moisture and had a negative effect on soybean yield (−14%). The effect of the rain exclusion treatment on soybean performance was similar across all tree row distances and in both root-pruning treatments, which is contrary to our prediction. In 2018, an abnormally dry and warm season, yield near the alley centres was higher than near the tree row and tended to outperform the control. In 2019, a season with normal rainfall and temperature, soybean yield within the alleys was consistent among the different measured distances and did not differ from that in the control. Moderate shading at 4 m (−26% of PAR) was not associated with a change in soybean yield or leaf traits compared to other distances where shading was negligible or absent. Root pruning negatively affected soybean yield in 2018 (−14%) and 2019 (−22%), which is contrary to our prediction. SIGNIFICANCEThis case study adds to our knowledge regarding interactions between crops and trees in widely spaced TBI systems. TBI effects on spatial patterns of crop yield may vary substantially depending upon inter-annual variation in climatic conditions. This study suggests that more facilitative effects would prevail in dryer and warmer years, in contrast to near neutral effects in normal years.

Shading Inhibits Sugar Accumulation in Leaf and Fruit of Jujube (Ziziphus jujuba Mill.)

Jujube is a characteristic light-demanding fruit tree, but fruit quality is frequently degraded because of the weak light in protected cultivation facilities in south China. In this study, a black shade net was used to set three light intensities artificially: no shading (0%, control, NS), moderate shading (45%, MS), and severe shading (76%, SS) to investigate the effect of low light on sugar metabolism of jujube. Compared with NS, chlorophyll and carotenoid contents in shaded leaves were increased, while specific leaf weight was decreased. A decrease in sucrose content, rather than fructose and glucose, was the main factor affecting sugar content in shaded leaves and fruits. Low expression of ZjSS2 and ZjSS3 inhibited sugar synthesis in shaded leaves, thereby reducing sucrose content by 23.7% in SS leaf than that in NS. Compared with NS, sucrose content in SS fruit was decreased by 58.1%, which was mainly caused by the down-regulated expression of ZjSS2 and ZjSPS1. In conclusion, sugar accumulation in leaf and fruit with shading treatment was suppressed, which was associated with differential transcription levels of related metabolic genes. The study provides new insights into sugar metabolism in leaf and fruit of phototropic plants under low light environments, such as jujube.

Shade effects on yield across different Coffea arabica cultivars — how much is too much? A meta-analysis

The coffee research community has maintained a long ongoing debate regarding the implications of shade trees in coffee production. Historically, there has been contrasting results and opinions on this matter, thus recommendations for the use of shade (namely in coffee agroforestry systems) are often deemed controversial, particularly due to potential yield declines and farmers’ income. This study is one of the first demonstrating how several Coffea arabica cultivars respond differently to shade with respect to yield. By standardising more than 200 coffee yield data from various in-field trials, we assembled the so-called “Ristretto” data pool, a one of a kind, open-source dataset, consolidating decades of coffee yield data under shaded systems. With this standardised dataset, our meta-analysis demonstrated significant genotypic heterogeneity in response to shade, showing neutral, inverted U-shaped and decreasing trends between yield and shade cover amongst 18 different cultivars. These findings encourage the examination of C. arabica at the cultivar level when assessing suitability for agroforestry systems. Comparison of productivity is also encouraged across a range of low to moderate shade levels (10–40%), in order to help elucidate potential unknown optimal shade levels for coffee production.

Biophysical drivers of yield gaps and ecosystem services across different coffee-based agroforestry management types: A global meta-analysis

The productivity of agroforestry systems (AFSs) and the provisioning of associated ecosystem services (ESs) are threatened by increasing cropping intensification and climate change. Compared to full-sun coffee, maintaining shade cover might protect against climate variability, forest degradation, and pests/diseases attack. However, there may be trade-offs between yields and ESs. While the impacts of shade have been reviewed, a global synthesis to understand how shade trees and a range of practices and biophysical factors contribute to yield gaps and ESs across management types is lacking. This research aims at integrating quantitative data on management practices (shade cover percentage, tree/coffee plant densities, and nutrient inputs), coffee/tree characteristics, soil properties, topographic attributes and climate, in order to compare the responses of coffee yields, biodiversity and ES supply across management types. We conducted a meta-analysis with a total of 142 papers that fulfilled the inclusion criteria and analyzed the individual and combined effects of these factors. The results show that factors such as shade cover and tree/plant densities affected more the yields than climatic and biotic factors. AFSs under moderate shade cover levels (35–50%), with tree densities between 100 and 250 trees ha−1, at low altitudes, and with steeper slopes provided as much yields as full-sun systems (4.1 ± 2.88 tons ha−1 yr−1). While increased shade cover (>51%) decreased yields, the results also show that more diversified AFSs can support biodiversity conservation and provide ESs such as stored carbon, infiltration, pollination, and water runoff. The generalized linear models (GLMs) analyses showed that coffee yield variations are highly context-dependent and factors such as the incidence of pest/leaf rust, altitude, soil quality, available water, and biodiversity may play an important role. The novelty of this research is that the effect of shade, coffee plants, and input management practices is taken into account, along with the effects of a range of site-specific biophysical factors; along with the application of a case study to test robustness of the meta-analysis. This study provides an understanding of the effects of management type gradients on coffee yield and whether the low yields in AFSs compared to conventional coffee monocultures, are compensated by the provisioning of ESs.

Response strategies of woody seedlings to shading and watering over time after topsoil translocation in dry-hot karst region of China

Translocating topsoil from an appropriate donor forest is a promising strategy to restore seriously degraded sites. However, some dominant or constructive species did not survive due to plant stress in the seedling stage, which ultimately led to a poor community structure and low similarity between new communities and donor forest. In this study, we replaced the topsoil of karst rocky desertification with forest topsoil and imposed different shading and watering treatments following quadratic saturation D-optimum design. Richness, abundance, height and base diameter of woody species (trees + shrubs) were measured yearly to construct mathematical equation between them and shade degrees (SD) and water quantity (WQ) by using multiple stepwise regression. Results displayed a positive linear relationship between richness of woody species and SD at the second year of topsoil translocation, which changed to a parabolic relationship at the fifth year with a maximum 30.8 species when SD was 37.5 %. The positive linear relationship between density of woody species, shrubs and trees and SD at the second year transformed into a parabolic relationship at the fifth year, and density reached maximum 6.3, 3.7 and 3.8 seedlings/m2 when SD were 41.7, 38.9 and 45.0%, respectively. In contrast, the density of Paliurus orientalis and Sophora viciifolia turned into a negative linear relationship with SD at the fifth year. Moreover, although the effect of SD and WQ on height of woody species increased over time, shading inhibited base diameter of shrubs and height of Quercus cocciferoides, Sapium sebiferum and Fraxinus malacophylla at the fifth year. We concluded that no-shading and heavy shading reduced species diversity, and light to moderate shading should be recommended in first 2–3 years after topsoil translocation to enhance woody species survival and accelerate similar forest community establishment providing guidance for the management, regeneration and restoration of native forest in semi-arid areas.

No Reduction in Yield of Young Robusta Coffee When Grown under Shade Trees in Ecuadorian Amazonia.

Little is known on what impact shade trees have on the physiology of Coffea canephora (robusta coffee) under tropical humid conditions. To fill this gap, a field experiment was conducted in the Ecuadorian Amazon to investigate how growth, nutrition (leaf N), phenological state (BBCH-scale) and yield of 5-year-old robusta coffee shrubs are affected by the presence or absence of leguminous trees, the type (organic v conventional) and intensity of management. The experiment was a factorial 5 × 4 design with four cropping systems: intensive conventional (IC), moderate conventional (MC), intensive organic (IO) and low organic (LO), and with five shading systems in a split-plot arrangement: full sun (SUN), both Erythrina spp. and Myroxylon balsamum (TaE), M. balsamum (TIM), E. spp. (ERY) and Inga edulis (GUA). Three monthly assessments were made. Cherry yields of coffee shrubs under moderate shade (c. 25%) were similar to those under high light exposure. Coffee shrubs grown with either E. spp. or I. edulis were taller (+10%) and had higher leaf N concentrations (22%) than those grown without consistent shade. Unless receiving c. 25% of shade, coffee shrubs grown under organic cropping systems showed reduced growth (25%). No correlation was found between height, cherry yield and leaf N. Both shading and cropping systems affected leaf N concentration, also depending on phenological state and yield. Further research is needed to confirm our findings in the long-term as well as to elucidate how leguminous trees may induce physiological responses in robusta coffee under humid tropical conditions.

Flooding tolerance of four tropical peatland tree species in a nursery trial.

In order to facilitate hydrological restoration, initiatives have been conducted to promote tree growth in degraded and rewetted peatlands in Indonesia. For these initiatives to be successful, tree seedlings need to be able to survive flooding episodes, with or without shade. We investigated the survival rates and the formation of adventitious roots in the case of four tree species exposed to combinations of different shading and water levels under controlled conditions in a nursery, with artificial rainwater and with peat soil as the medium. The research focused on the following questions (i) whether trees can grow on flooded peat soils; and (ii) which plant traits allow plants to cope with inundation, with or without shade. The four tree species compared (Shorea balangeran, Cratoxylum arborescens, Nephelium lappaceum and Durio zibethinus) include two natural pioneer and two farmer-preferred fruit trees. The experiment used a split-split plot design with 48 treatment combinations and at least 13 tree-level replicates. The study found that S. balangeran and C. arborescens had relatively high survival rates and tolerated saturated condition for 13 weeks, while N. lappaceum and D. zibethinus required non-saturated peat conditions. S. balangeran and C. arborescens developed adventitious roots to adapt to the inundated conditions. D. zibethinus, S. balangeran and N. lappaceum grew best under moderate (30%) shading levels, while C. arborescent grew best in full sunlight.

Moderate shading did not affect barley yield in temperate silvoarable agroforestry systems

With climate change and an increasing global human population, the concept of agroforestry is gaining economic and environmental interest. The practice of growing trees and crops on the same land is mainly applied in (sub)tropical climate and rarer in temperate areas where farmers fear decreased understorey crop yields due to competition with trees. However, whether competition is stronger below- (soil moisture, nutrients) or aboveground (light) in a temperate silvoarable agroforestry system (AFS) is not clear. The effects of different treatments of light, water and nutrient availability on crop production in two temperate AFS in Central Switzerland were investigated, where summer barley (Hordeum vulgare L.) was grown as understorey crop under 90%, 40% and 0% shade nets, with and without irrigation and/or fertilisation in a fully factorial design. Yield was reduced by 26% under heavy shade; yield reductions under moderate shade were not significant. Fertilisation and irrigation increased crop yield by 13% and 6–9%, respectively, independent from shade. Individual seed mass was significantly increased by fertilisation from an average of 0.041 g (± 0.008 SD) in unfertilised treatments to an average of 0.048 g (± 0.010) in fertilised treatments. Fertilisation had the biggest impact on total seed number (p < 0.001) with on average 36 (± 26) seeds per individual in unfertilised plots and 61 (± 33) in fertilised plots. This study demonstrates that moderate shade (as can be expected in modern AFS) was not a major limiting factor for barley yield in these two AFS in Switzerland, indicating that AFS with appropriate management combined with suitable selection of understorey crops are an option for agricultural production in temperate regions without significant yield losses.

Leaf anatomy, photosynthesis, and chloroplast ultrastructure of Heptacodium miconioides seedlings reveal adaptation to light environment

Light intensity is a critical factor for the plant survival and early growth. Heptacodium miconioides , a well-accepted ornamental plant, has been endangered due to fragmented habitats in the wild. To better understand the light adaptation mechanisms of H. miconioides , we investigated the morphology, photosynthesis, chloroplast ultrastructure, and chloroplast gene expression of the leaves under high light (HL), moderate light (ML), and low light (LL) conditions. With decreasing light intensity, the specific leaf area and chlorophyll contents of H. miconioides increased, whereas the leaf size first increased followed by a decrease. The maximum net photosynthetic rate under ML and HL treatments were significantly higher than that under LL treatment. However, leaves under ML treatment exhibited the lower dark respiration rate and light compensation point than those under HL treatment. The leaf thickness, palisade tissue, spongy tissue, and stomatal density were obviously reduced with decreasing light intensity. Chloroplast ultrastructure showed the better development in leaves under ML condition, and the size of chloroplast, the number of starch grains and plastoglobules increased significantly. In addition, the expression levels of genes involved in chlorophyll biosynthesis ( HEMA , CLH , CHLI , CHLH , CHLG ) were higher under ML than LL treatment, but lower under HL treatment. The up-regulation of the photosystem II ( PsbB , PsbD , PsbO ) genes expression play an important role in under ML and LL treatments. Taken together, we proposed that the optimal growth of H. miconioides seedlings varies between HL and ML but had poor growth under LL condition. The improvement in H. miconioides growth under moderate shade was mainly through its effects on leaf morphology, chloroplast development, and light capture efficiency of PSII phase. • Adaptation mechanisms to different light intensity were investigated in Heptacodium miconioides . • Seedlings grown under moderate and high light intensities exhibited higher photosynthetic capacity. • Moderate light intensity increased the size of chloroplast and the accumulation of starch grains and plastoglobules. • Moderate light intensity up-regulated chlorophyll biosynthesis and photosystem II (PSII) related gene expression.

Impact of Olive Trees on the Microclimatic and Edaphic Environment of the Understorey Durum Wheat in an Alley Orchard of the Mediterranean Area

In the current context of climate change, the impact of trees in agroforestry systems is expected to mitigate water and heat stresses, particularly in semi-arid environments. Within this framework, in a two-year trial conducted at INRAE in Southern France, the dynamics of microclimatic parameters and the edaphic environment of durum wheat were investigated under a yearly-pruned (AF) and a never-pruned (AF+) 6-m apart alley olive orchard, in comparison with controls under full sun. Here it was recorded a reduction of photosynthetic active radiation (PAR) by 30% and 51% in AF and AF+, respectively, during the wheat cycle, together with a marked reduction of wind speed compared to controls (–85% in AF and −99% in AF+). A significant buffer effect was also highlighted for air temperature, averagely +1.7 °C during the night and −3.2 °C during the daytime under the moderate shading of AF. The positive effect of trees on soil water conservation increased with the intensity of shading, particularly during the critical wheat stage of grain filling, with benefits on wheat root mycorrhization, and NH4+ and NO3− abundance in the arable layer. Despite some of the environmental modifications being favorable for the understorey wheat, these were not translated into yield improvements, suggesting that the severe shading associated with the small inter-row and evergreen trees has a prevailing effect, that requires to be managed through appropriate tree pruning.

Layering contrasting photoselective filters improves the simulation of foliar shade

BackgroundNeutral density shade cloth is commonly used for simulating foliar shade, in which it reduces light intensity without altering spectral quality. However, foliar shade also alters spectral quality, reducing the ratio of red to far-red (R:FR) light, altering the ratio of blue to green (B:G) light, and reducing ultraviolet light. Unlike shade cloth, photoselective filters can alter spectral quality, but the filters used in previous literature have not simulated foliar shade well. We examined the spectral quality of sunlight under color temperature blue (CTB), plus green (PG), and neutral density (ND) filters from LEE Filters, Rosco e-colour + and Cinegel brands either alone or layered, hypothesizing that the contrasting filter qualities would improve simulations. As a proof-of-concept, we collected spectral data under foliar shade to compare to data collected under photoselective filters.ResultsUnder foliar shade reductions in the R:FR ratio ranged from 0.11 to 0.54 (~ 1.18 in full sun), while reductions in the B:G ratio were as low as 0.53 in deep shade, or were as high as 1.11 in moderate shade (~ 0.87 in full sun). Neutral density filters led to near-neutral reductions in photosynthetically active radiation and reduced the R:FR ratio similar to foliar shade. Color temperature blue filters simulated the increased B:G ratio observed under moderate foliar shade, but did not reduce the R:FR ratio low enough. On their own, PG filters did not simulate any type of foliar shade. Different brands of the same filter type also had disparate effects on spectral quality. Layered CTB and ND filters improved the accuracy of moderate foliar shade simulations, and layering CTB, PG, and ND filters led to accurate simulations of deep foliar shade.ConclusionsLayering photoselective filters with contrasting effects on the spectral quality of sunlight results in more accurate simulations of foliar shade compared to when these filters are used separately. Layered filters can re-create the spectral motifs of moderate and deep foliar shade; they could be used to simulate shade scenarios found in different cropping systems. Photoselective filters offer numerous advantages over neutral density shade cloth and could be a direct replacement for researchers currently using neutral density shade cloth.

Tussock and tiller population dynamics on rotationally stocked Piatã palisadegrass (

Context Integrated crop–livestock–forestry systems can be an alternative to monoculture pastures; however, the effect of the arboreal component on tillering and tussock dynamics of understorey grass canopy is not well understood. Aims Our objective was to evaluate the patterns of tillering dynamics, population stability and tussock distribution of Piatã palisadegrass (Urochloa brizantha) as affected by contrasting shading regimes in the Brazilian Amazon biome. Methods The following three shading regimes were assessed: pasture with no trees (no shading, NS), moderate shading (MS, 338 trees ha−1), and intense shading (IS, 714 trees ha−1). Pastures were rotationally grazed by dairy heifers. Paddocks from MS and IS were stratified into three sampling strips, including two closer to the tree rows (i.e. lateral) and one between the two lateral strips (i.e. central). Two methods for monitoring sward canopy light interception (LI) were used for IS regime, namely, LI taken under the tree canopy (i.e. inside) and LI was taken above the tree canopy (i.e. outside). Key results Relative to NS, there was a reduction in photosynthetically active radiation transmittance of 18.1% and 37.1% on MS and 49.9% and 52.0% on IS for central and lateral shading strips respectively. Overall, the increase in shading level was associated with a decrease in average tussock perimeter, tiller population density, and an increase in the frequency of bare ground. Conclusions Our findings clearly indicate the key role of the light environment as a determinant of Piatã palisadegrass horizontal structure. Implications It highlights the importance of planning the levels of tree density and layout in areas of crop–livestock–forestry integration.

EMPIRICAL USE OF THREE OAK SPECIES IN AFFORESTATION: LESSONS FROM SOWING AND TRANSPLANTING EXPERIMENTS

The effects of different factors on the growth in height and diameter of oak saplings in comparative cultures were estimated: progeny from autumn and spring sowing of acorns (1); growing conditions of pedunculate oak (Quercus robur L.) mother plants (2); the initial planting density of sessile oak (Q. petraea Liebl.) (3); natural lightening level of downy oak (Q. pubescens Willd.) mother plants (4). The pedunculate oak seedlings obtained after spring sowing were characterized by faster growth compared with those obtained from the autumn sowing. The lower growth rate observed in seedlings sown in autumn was due to the prolonged frosty weather during winter, which led to a decrease in acorn viability and progeny vigour. Due to the higher genetic diversity of the progeny obtained from the free-pollinated pedunculate oaks, it is possible that their growth was more intense and stable in comparison to those of saplings obtained from the acorns of isolated trees. The planting under the forest canopy had a clear influence on the growth in height of saplings. At low density levels (1.0 x 1.0 m), the sessile oak saplings benefited from larger availability of soil nutrients and displayed the highest growth, contrasting with those planted at high density (0.5 x 0.5 m). The deep and moderate shading caused a substantial reduction in the growth of downy oak saplings. Therefore, when planting, it is recommended to avoid using fast-growing species, which, due to asymmetric competition, could drastically reduce the growth in height of the downy oak saplings. Prolonged regeneration of the pruned root system following the transplantation process of sessile and downy oak seedlings determined their very slow growth in the first years of life.

Performance of diploid and interploid hybrids of St. Augustinegrass under moderate shade

AbstractShadetolerance is an important factor for cultivar selection in urban areas. Diploid (2n = 2x = 18) cultivars of St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] with moderate to high shade tolerance have been popular choices for residential and commercial landscapes in the southern United States. This study evaluated 26 elite drought resistant diploid and interploid (polyploid × diploid) hybrids and four commercial cultivars under 75% continuous shade from 20 June 2017 through 30 Oct. 2018. Biweekly data were collected during the growing season for percent green cover, visual turfgrass quality, canopy color, shoot density, and daily leaf elongation rates (DER; mm d–1). Spring greenup was rated annually, and to gray leaf spot incidence was rated when naturally occurring. All genotypes lost green cover through 2017, and greenup was delayed transitioning into the summer of 2018 when most diploids struggled to recover from disease, shade, and winter injury whereas, on an average, interploid hybrids reached up to 84.0% green cover. Daily leaf elongation rates were lower for diploids than polyploids in both years. Turfgrass quality, color, and density generally declined under shade as expected. Overall, three interploid hybrids (DALSA 1329, 1404, and 1406) were the top performers demonstrating good retention of turfgrass performance traits and reduced DER under shade.

Recent advances in maize production in integrated systems: A review

Maize is an important crop around the world supporting food security, especially in developing countries. The increasing demand for food and renewable energy resources has been supported studies of competitiveness and complementarity interactions between trees, crops, and animals. Thus, the integrated systems should promote a synergic relationship between the components, resulting in greater production of crops, animals, and forestry. Our objective was to describe recent advances on maize production in integrated systems and how recent research can contribute to intensify and/or diversify the production system. The current literature supports the following appointments. The increase in the soil organic carbon in integrated systems improves the physical (density and aggregate stability), chemical (nutrient retention), and biological (greater diversity and microbial mass) properties. Great grain yield and input reduction are possible with the microbial inoculants' use. The inoculants' action is maximized when associated with fertilizers and/or biochar. The biochar acts as a soil conditioner, increasing the water and nutrients retention in the soil, favoring the maize growth. Maize can be grown in the understory (moderate shade), but productivity will be reduced. Thus, we identified the need for research on shading-tolerant genotypes, intercropped management to minimizes competition, quantification of the stratified light profile by a system component (tree, maize, and grass), and more complex and accurate mathematical models to support decisions in the integrated systems arrangements. Understanding these practices would encourage producers to enhance the use of integrated systems.