Tree ecophysiology in the context of climate change

Forest structure and function strongly depend on and concurrently influence environmental conditions.Tree performance is generally governed by its genetics and environment;thus,recent hotspots in this field include tree genotype×environment,phenotype×environment,and functional trait×environment interactions.The editorial,review,and 22 original research articles in this Special Issue,"Tree ecophysiology in the context of climate change",highlight ecophysiological phenomena(e.g.,climate hormesis,seed germination,tree mortality),processes(e.g.,tree metabolism,photosynthate allocation,nutrient uptake and transport),indicators(e.g.,carbon sequestration,pollutants),measurements(e.g.,thermal time methods,soil quality indices,vegetation spectral index,and near-infrared leaf reflectance),and modeling(e.g.,climate correlations with tree growth,photo synthetic phenology,hydraulic strategies,OliveCan model)in the context of global climate change.Understanding forest-environment interactions from an ecophysiological perspective as climate changes provides insights into species fitness in suboptimal environments,species competition for limited resources,and phylogenetic divergence or convergence of species,and predicting species distributions.

Overview of the distribution and adaptation of a bloom-forming cyanobacterium Raphidiopsis raciborskii:integrating genomics,toxicity,and ecophysiology

Raphidiopsis raciborskii is a notorious bloom-forming and filamentous cyanobacterium that has been extensively investigated into its toxicity,phylogeny,and spreading potential.Studies have demonstrated that this species has spanned different climates from tropical zones to temperate regions,suggesting that R.raciborskii is becoming a cosmopolitan species in freshwater systems around the world.In fact,it has been proposed that several characteristics of R.raciborskii may explain its spread and dominance.In particular,R.raciborskii is known to display a high extent of physiological plasticity regarding nutrients,light regimes,and te mperature s.Moreover,this species illustrates different ecotype s with distinct environmental requirements.Here,we present an overview of R.raciborskii’s global distribution and adaptation strategy based on the recent findings from genome variance,toxicity,and ecophysiology.The expansion of its geographical distribution can be linked to its genome,toxicity,and ecophysiology.The variable genes are mainly associated with the stress response,phage defense,DNA repair,cell cycle control,and membrane transport,illustrating the species’adaptability in response to changing environments.In fact,the species shows rapid adaptability to low and/or variable nutrient availability,especially changing phosphorus availability.Moreover,the variabilities of strains within the population extend their flexibility to adapt and acclimate to ambient environment.In addition,cylindrospermopsins(CYN)appear to have a potential biological role in facilitating theirs dominance or bloom.These strategies of R.raciborskii make it a challenge to manage in a fre shwater system,reflecting the management of its bloom from further evidence of the complex ecophysiology,toxicity,and genome of this species.

Stress-Tolerant Cassava: The Role of Integrative Ecophysiology-Breeding Research in Crop Improvement

This review highlights an integrative multidisciplinary eco-physiological, breeding and agronomical research on the tropical starchy root crop cassava conducted at CIAT. Laboratory and field studies have elucidated several physio-logical/biochemical mechanisms and plant traits underlying the high productivity in favorable conditions and tolerance to stressful environments, such as prolonged water stress and marginal low-fertility soils. Cassava is endowed with inherent high photosynthetic capacity expressed in near optimal environments that correlates with biological produc- tivity across environments and wide range of germplasm.Field-measured photosynthetic rates were also associated with root yield, particularly under prolonged drought. Extensive rooting systems and stomatal sensitivity to both atmospheric humidity and soil water shortages underlie tolerance to drought. The C4 phosphoenolpyruvate carboxylase (PEPC) was associated with photosynthesis and yield making it a selectable trait, along with leaf duration, particularly for stressful environments. Germplasm from the core collection was screened for tolerance to soils low in P and K, resulting in the identification of several accessions with good levels of tolerance. Cassava has a comparative advantage against major tropical food and energy crops in terms of biological productivity. Results also point to the importance of field research versus greenhouse or growth-chamber studies. In globally warming climate,the crop is predicted to play more role in tropical and subtropical agro-ecosystems. More research is needed under tropical field conditions to understand the interactive responses to elevated carbon dioxide, temperature, soil fertility, and plant water relations.

Ecophysiology of Lake Kinneret (Israel) Zooplankton

A summary of a long-term research of Lake Kinneret zooplankton distribution is presented. During 1969-2002 several prominent changes have been recorded in the Kinneret ecosystem. This paper is an attempt aimed at analyzing the impact of these ecological changes on the zooplankton communities. The impacts of Phytoplankton, Bacteria, Protozoa, Temperature, Nutrient composition and fish predation on zooplankton dynamics are analyzed. It was found that periodical fluctuations of zooplankton density were mostly affected by fish predation as well as by temperature increase and food availability. Ecological conditions in Lake Kinneret have been modified since early 1990’s and the new conditions were consequently accompanied by zooplankton Homeostatic response. Moreover, as a result of the ecological changes fish intensified their pressure on zoo-plankton. The flexibility of food resource preference by zooplankton enabled its existence but fish predation predominantly controlled their density.

Photosynthetic response to a winter heatwave in leading and trailing edge populations of the intertidal red alga Corallina offi-cinalis(Rhodophyta)

Marine heatwaves(MHWs)caused by anthropogenic climate change are becoming a key driver of change at the ecosystem level.Thermal conditions experienced by marine organisms across their distribution,particularly towards the equator,are likely to approach their physiological limits,resulting in extensive mortality and subsequent changes at the population level.Populations at the margins of their species’distribution are thought to be more sensitive to climate-induced environmental pressures than central populations,but our understanding of variability in fitness-related physiological traits in trailing versus leading-edge populations is limited.In a laboratory simulation study,we tested whether two leading(Iceland)and two trailing(Spain)peripheral populations of the intertidal macroalga Corallina officinalis display different levels of maximum potential quantum efficiency(Fv/Fm)resilience to current and future winter MHWs scenarios.Our study revealed that ongoing and future local winter MHWs will not negatively affect leading-edge populations of C.officinalis,which exhibited stable photosynthetic efficiency throughout the study.Trailing edge populations showed a positive though non-significant trend in photosynthetic efficiency throughout winter MHWs exposure.Poleward and equatorward populations did not produce significantly different results,with winter MHWs having no negative affect on Fv/Fm of either population.Additionally,we found no long-term regional or population-level influence of a winter MHWs on this species’photosynthetic efficiency.Thus,we found no statistically significant difference in thermal stress responses between leading and trailing populations.Nonetheless,C.officinalis showed a trend towards higher stress responses in southern than northern populations.Because responses rest on a variety of local population traits,they are difficult to predict based solely on thermal pressures.

From ecophysiology to cultivation methodology:filling the knowledge gap between uncultured and cultured microbes

Earth is dominated by a myriad of microbial communities,but the majority fails to grow under in situ laboratory conditions.The basic cause of unculturability is that bacteria dominantly occur as biofilms in natural environments.Earlier improvements in the culture techniques are mostly done by optimizing media components.However,with technological advancement particularly in the field of genome sequencing and cell imagining techniques,new tools have become available to understand the ecophysiology of microbial communities.Hence,it becomes easier to mimic environmental conditions in the culture plate.Other methods include co-culturing,emendation of growth factors,and cultivation after physical cell sorting.Most recently,techniques have been proposed for bacterial cultivation by employing genomic data to understand either microbial interactions(network-directed targeted bacterial isolation)or ecosystem engineering(reverse genomics).Hopefully,these techniques may be applied to almost all environmental samples,and help fill the gaps between the cultured and uncultured microbial communities.

Soil resource availability and its effect on the ecophysiology and establishment of Stipa pulchra

Aims The objectives of this study were to(i)determine the importance of soil moisture and soil nitrogen availability as resource requirements for the establishment of Stipa pulchra,(ii)to examine how changes in slope within a local habitat can affect the accumulation of soil moisture and soil nitrogen and(iii)to measure the physiological re-sponses of S.pulchra among such slope locations.Methods The field experiment occurred in the San JoséHills of Southern California on the California State Polytechnic University,Pomona campus.Plots were established within three different slope loca-tions(shallow,moderate and steep)within four separate canyons.Three nitrogen treatments(ambient,addition and removal)were replicated within each slope location for all four canyons,and five S.pulchra plants were planted in each plot.Soil nitrogen accumula-tion and soil moisture,as well as other abiotic variables,were meas-ured across the varied slope locations and nitrogen treatments.We measured the cover,stress,and reproduction of S.pulchra plants for 2 years and used a mesocosm experiment to determine how S.pul-chra responds to varying water and nitrogen availability.Important Findings Stipa pulchra had a strong positive response to the wettest watering treatment and a weak response to nitrogen addition in the meso-cosm experiment.In the field experiment,S.pulchra responded positively in moderate slope locations and did not respond to ni-trogen treatments,possibly due to drought.Field patterns of soil moisture were driven by slope,soil compaction and solar radi-ation.Soil nitrogen accumulation did not vary among slope lo-cations.For restoration of S.pulchra,priority should be placed on managing soil moisture availability and determining suitable edaphic factors.

Leaf hydraulics coordinated with leaf economics and leaf size in mangrove species along a salinity gradient

Independence among leaf economics,leaf hydraulics and leaf size confers plants great capability in adapting to heterogeneous environments.However,it remains unclear whether the independence of the leaf traits revealed across species still holds within species,especially under stressed conditions.Here,a suite of traits in these dimensions were measured in leaves and roots of a typical mangrove species,Ceriops tagal,which grows in habitats with a similar sunny and hot environment but different soil salinity in southern China.Compared with C.tagal under low soil salinity,C.tagal under high soil salinity had lower photosynthetic capacity,as indicated directly by a lower leaf nitrogen concentration and higher water use efficiency,and indirectly by a higher investment in defense function and thinner palisade tissue;had lower water transport capacity,as evidenced by thinner leaf minor veins and thinner root vessels;and also had much smaller single leaf area.Leaf economics,hydraulics and leaf size of the mangrove species appear to be coordinated as one trait dimension,which likely stemmed from covariation of soil water and nutrient availability along the salinity gradient.The intraspecific leaf trait relationship under a stressful environment is insightful for our understanding of plant adaption to the multifarious environments.

Species divergence in seedling leaf traits and tree growth response to nitrogen and phosphorus additions in an evergreen broadleaved forest of subtropical China

Tree competitiveness generally depends on trait plasticity in response to environmental change.The effects of nitrogen(N)and phosphorus(P)on leaf trait variability by species is poorly understood,especially in China’s subtropical forests.This study examined the seedling leaf traits and net primary productivity of all trees>5 cm DBH of two dominant species,Schima superba and Castanopsis carlesii,in an evergreen broadleaved forest fertilized with nitrogen(+N),phosphorus(+P),and nitrogen plus phosphorus(N+P).The effect of N on seedling leaf traits was stronger than P,while fertilization in general was species dependent.Leaf mass per unit area decreased with N for S.superba seedlings but not for C.carlesii.Leaf N,P,and N/P ratios changed with N addition for both species.All four N fractions of carboxylation,bioenergetics,cell wall,and other N metabolites in C.carlesii leaves responded significantly to fertilization,while only the cell wall in S.superb a leaves responded.Other leaf functional traits,including light-saturated photosynthetic rates,water,N,and P use efficiencies,chlorophyll and non structural carbohydrate contents increased with N addition in S.superb a and by P addition in C.carlesii.Canopy closure at the stand-level increased due to N.Litter biomass and relative growth rate of S.superb a was not affected by any treatments,while both for C.carlesii significantly decreased with N+P addition.Collectively,nutrient limitation may vary at a small scale among species in a subtropical forest based on their responses of seedling traits and net primary productivity to fertilization.Seedling traits are not correlated with the net primary productivity of larger trees except for N fractions,because low light conditions induced by fertilization reduces the proportion of N allocated to photosynthesis in seedlings.In addition,acclimation differences of tree species may increase the uncertainty of community succession.

Multi-year throughfall reduction enhanced the growth and non-structural carbohydrate storage of roots at the expenses of above-ground growth in a warm-temperate natural oak forest

The more frequent occurrence and severer drought events resulting from climate change are increasingly affecting the physiological performance of trees and ecosystem carbon sequestration in many regions of the world.However,our understanding of the mechanisms underlying the responses and adaption of forest trees to prolonged and multi-year drought is still limited.To address this problem,we conducted a long-term manipulative throughfall reduction(TFR,reduction of natural throughfall by 50%–70%during growing seasons)experiment in a natural oriental white oak(Quercus aliena var.acuteserrata Maxim.)forest under warm-temperate climate.After seven years of continuous TFR treatment,the aboveground growth in Q.aliena var.acuteserrata started to decline.Compared with the control plots,trees in the TFR treatment significantly reduced growth increments of stems(14.2%)and leaf area index(6.8%).The rate of net photosynthesis appeared to be more susceptible to changes in soil water in trees subjected to the TFR than in the control.The TFR-treated trees allocated significantly more photosynthates to belowground,leading to enhanced growth and nonstructural carbohydrates(NSC)storage in roots.The 7-year continuous TFR treatment increased the biomass,the production and the NSC concentration in the fine roots by 53.6%,153.6%and 9.6%,respectively.There were clear trade-offs between the aboveground growth and the fine root biomass and NSC storage in Q.aliena var.acuteserrata trees in response to the multi-year TFR treatment.A negative correlation between the fine root NSC concentration and soil water suggested a strategy of preferential C storage over growth when soil water became deficient;the stored NSC during water limitation would then help promote root growth when drought stress is released.Our findings demonstrate the warm-temperate oak forest adopted a more conservative NSC use strategy in response to long-term drought stress,with enhanced root growth and NSC storage at the expenses of above-ground growth to mitigate climate changeinduced drought.

Effects of Variety and Planting Density on Mung Bean Eco-Physiology and Yield in the Southeastern US

Mung bean (Vigna radiata L. Wilczek.) is a warm-season, C3 pulse crop of the legume family that has been widely cultivated in Asian countries. As the demand for mung bean continues to increase in the United States, the ecophysiology, growth, and yield of mung bean varieties in the southeastern US need to be assessed. A field experiment was conducted at the Agricultural Research and Education Center of Tennessee State University to investigate the effects of four varieties (OK2000, Berken, TSU-1, AAMU-1) and three planting densities (5, 10, and 15 cm spacing) on the ecophysiology and yield of mung bean. Results showed that the relative chlorophyll content, plant height, pod dry biomass, pod number, crop yield, and harvest index significantly varied among the varieties. Density only influenced transpiration, relative chlorophyll content, and plant dry biomass. OK2000 had 101.0% more pods per plant and a 42.4% higher harvest index and produced a 45.3% higher yield than other varieties, but no significant difference in yield was found among the other three varieties. This study demonstrated that the mung bean variety OK2000 with a high yield would be ideal for commercial production in the southeastern US.

The Influence of Induced Drought Stress on Germination of Cenchrus ciliaris L.and Cenchrus setigerus Vahl.:Implications for Rangeland Restoration in the Arid Desert Environment of Kuwait

Drought impacts in arid desert ecosystems can result in decreased ecosystem productivity and biodiversity.Imple­mentation of restoration projects in arid desert environments is largely dependent on water availability and soil mois­ture condition.This study investigated the influence of induced drought stress by using polyethylene glycol(PEG-6000)solution on germination viz.Cenchrus ciliaris and Cenchrus setigerus as the important rangeland species.The water stress potential treatments were 0(control),-0.5 MPa,-1.0 MPa,-1.5 MPa,and-2.0 MPa.The extent of seed germi­nation was severely affected by decreased water stress potential.As drought increased,the percentage of germination decreased in both Cenchrus’species.The water deficit at-0.5 MPa showed a significant(P<0.001)reduction in the final germination percentage in the case of C.setigerus and C.ciliaris by 65%and 42.5%,respectively.At-1.0 MPa to-1.5 MPa,changes in intermediate germination were observed in C.ciliaris(from 35%to 17.5%,respectively)and C.setigerus(from 22.5%to 11.25%respectively).Higher levels of water stress(-2.0 MPa)prevented the survival of both species.Understanding the germination strategies of native desert plant species associated with drought stress and identifying favorable conditions during the germination process can be useful for restoration practices and rangeland management actions to improve desert ecosystems and maintain biodiversity.

Relationship Between Ecophysiological Features and Grain Yield in Different Soybean Varieties

Photosynthetic rate ( P n ), transpiration rate ( E ), stomatal conductance ( g s ), water use efficiency ( WUE ), intercellular CO 2( C i ) and leaf water potential ( Ψ ) in varieties of soybean ( Glycine max (L.) Merr.) measured in the past three decades (1970s, 1980s and 1990s) and their inter_relationships were analyzed. These parameters of soybean changed with development stages. It is shown that there was a strongly positive relationship between the yield of soybean and its net photosynthetic rate. Soybean varieties with high yield potential had higher P n , g s and Ψ than those with low yield potential. Their values of C i were remarkably lower. Such relationship was especially remarkable at the critical stage of pod_bearing. P n of soybean of high yield was obviously higher than that of low yield. Of the different stages, the highest P n was found in the pod_bearing stage and other values were higher, too. P n and Ψ of modern soybean varieties were higher and such was continuing. Increased partitioning of carbon to seed and the size of sink may also be important for yield formation when P n values were remarkably higher in the pod_bearing stage.

Short-term effects of different fire severities on soil properties and Pinus halepensis regeneration

Considering that diverse fire severities can affect soil properties differently,the aim of this study was to examine to what extent changes in soil properties caused by fire could condition seedling establishment.This new approach is for identifying a new fire cause-effect chain to qualify the impacts of fire on soils with the purpose of using fire as a tool in forest management to favour Pinus halepensis Mill.regeneration.The study area was a reforested P.halepensis area which had been crossed by fire for78.8 ha,causing various degrees of damage.The forest was subdivided into three large areas according to the gravity of crown scorch,[low(LS),medium(MS)and high(HS)severity],on the basis of needle yellowing which usually occurs after exposure to direct flames.Results showed significant differences in soil properties with respect to fire severity.In the HS area,total nitrogen and carbon were considerably reduced while ash and phosphorus contents significantly increased.The changes in soil properties,in particular to nutrient levels,affected P.halepensis regeneration,mainly the first year after the fire.Greater regeneration occurred in areas affected by moderate fire severity in which the temperatures reached increased the mineralization of soil organic matter with the consequent release of nutrients available for seedling growth.Additionally,moderate fire severity suppressed the regeneration of grasses,reducing the interspecific competition.Heights of seedlings were inversely proportional to the density of grasses.Where the number was abundant(LS),the height was modest;conversely,where the number was low(HS),the greater hypsometric differentiation of pine seedlings was observed.These results suggest that moderate fire severity represents an environmental stress(hormesis)altering microscale conditions to increase pine germination and establishment.The exposure of P.halpensis to a moderate environmental factor that is damaging at higher intensities,induces an adaptive beneficial effect on seedling regeneration.This data can re-evaluate the assertion that coniferous burned areas,if left unmanaged,would remain unproductive for an indefinite period.

Ecophysiological characteristics of four intertidal marine macroalgae during emersion along Shantou coast of China,with a special reference to the relationship of photosynthesis and CO_(2)

Intertidal marine macroalgae experience periodical exposures during low tide due to their zonational distribution. The duration of such emersion leads to different exposures of the plants to light and aerial CO2, which then affect the physiology of them to different extents. The ecophysiological responses to light and CO2 were investigated during emersion in two red algae Gloiopeltis furcata and Gigartina intermedia, and two brown algae Petalonia fascia and Sargassum hemiphyllum, growing along the Shantou coast of China. The light-saturated net photosynthesis in G. furcata and P. fascia showed an increase followed by slightly desiccation, whereas that in G. intermedia and S. hemiphyllumexhibited a continuous decrease with water loss. In addition, the upper-zonated G. furcata and P. fascia, exhibited higher photosynthetic tolerance to desiccation and required higher light level to saturate their photosynthesis than the lower-zonated G. intermedia and S. hemiphyllum. Desiccation had less effect on dark respiration in these four algae compared with photosynthesis. The light-saturated net photosynthesis increased with increased CO2 concentrations, being saturated at CO2 concentrations higher than the present atmospheric level in G. furcata, G. intermedia and S. hemiphyllum during emersion. It was evident that the relative enhancement of photosynthesis by elevated CO2 in those three algae increased, though the absolute values of photosynthetic enhancement owing to CO2 increase were reduced when the desiccation statuses became more severe. However, in the case of desiccated P. fascia (water loss being greater than 20 %), light saturated net photosynthesis was saturated with current ambient atmospheric CO2 level. It is proposed that increasing atmospheric CO2 will enhance the daily photosynthetic production in intertidal macroalgae by varied extents that were related to the species and zonation.

How does Cariniana estrellensis respond to different irradiance levels?

Based on reports that variables related to photosynthesis(net assimilatory ratio and chloroplast pigments)are more plastic than the morphological and biochemical variables in a climax tropical species,Cariniana estrellensis,under contrasting irradiance,we hypothesised that plasticity of gas exchange variables is higher in relation to growth,biochemical and anatomical variables.Plants that were 14 months old were subjected to200 up to 2000 lmol m^(-2)s^(-1) of photo synthetically active radiation(PAR)for 140 days.Growth increased up to1400 lmol m^(-2)s^(-1)PAR and then decreased at 2000 lmol m^(-2)s^(-1) PAR(full sunlight).This was related to the rate of photosynthesis(A)which showed the same tendency as photosystem Ⅱ performance index(PI_(ABS)).The greater thickness of the secondary xylem at 1400 lmol m^(-2)s^(-1) PAR indicated a higher water conductance capacity.The decrease in specific leaf area,elongation of mesophyll cells,and increase in stomatal density observed at higher irradiances were associated with higher leaf fructose and sucrose concentrations.We concluded that the better growth in partial shade was due to higher photosynthetic capacity.On the other hand,photosynthesis was inhibited equally in full sun and deep shade.The high adjustment capacity of C.estrellensis to wide amplitudes of irradiance was provided by greater plasticity of gas exchange variables in relation to growth,anatomical,and biochemical variables.

Brazilian Tropical Grassland Ecosystems: Distribution and Research Advances

A few decades ago we sought the understanding of the functioning of Brazilian ecosystems. During these years, changes in the way land use were influenced primarily by economic issues involving the process of valuation of land in different regions. Furthermore, developments in research have provided productive increments that were well characterized in some phases. This paper aims to trace a brief history of the distribution of grassland ecosystems in Brazil and show how it has been the advances in research on forages and pastures in the country, pointing its evolution, transition times and trends. Moreover, it purports to show a perspective of the dynamics of occupation of Brazilian territory by these ecosystems. The information is presented on three occasions, seeking to encourage understanding of where livestock grazing occurs and how the dynamics of occupation of the area was favored by the search. Also, it shows how the research was fundamental for Brazil occupy little arable areas considered, making the country one of the largest producers of cattle in the world.

Taxonomic and Ecological Characterization of Cyanobacteria from Some Brackish and Saline Lakes of Southern Transbaikal Region

Brackish and saline lakes are common in the arid zones of the Earth.They are unique ecosystems with extremely high p H values and high mineralization levels(up to saturating concentrations).These lakes are inhabited by

Effect of applying a calcined kaolin-based particle film on the photosynthetic capacity and growth of young eucalyptus plants

In scenarios of climatic change when increased global temperatures can be expected,it is essential to search for technologies that favor sapling survival and growth after planting and increase yield in the field.Kaolin-based particle films(KBPF)have been applied as barriers against the deleterious effects of high levels of solar radiation.The objective of the present study was to assess the effects of applying purified calcined kaolin-based particle film to young eucalyptus plants.Five treatments were carried out:0%(just water),3%,5%,7%,and 10%calcined kaolin applied to the adaxial part of the leaves.A complete randomized block design was used with five treatments and ten replicates.The plants were assessed for height,diameter at ground level,gas exchanges(net photosynthetic CO_(2) assimilation,stomatal conductance and transpiration),instantaneous(WUE)and intrinsic water use efficiency(IWUE),chlorophyll a fluorescence(maximum quantum yield of photosystem II(PSII)(Fv/Fm),concentration of active reaction centers in relation to the quantity of photons absorbed(RC/ABS)and the maximum ratio of quantum yields of photochemical and concurrent non-photochemical processes in PSII(Fv/F0),SPAD reading and leaf ontogeny.The 3%KBPF concentration showed the best responses in biometric assessments 80 days after planting(DAP)and were corroborated by the responses of the leaf,stem and shoot dry matter production as a whole.The leaf ontogeny assessments showed positive responses following KBPF application when considering leaf development,with 7%KBPF concentration resulting in the highest mean values.The mean specific leaf mass had negative response to high KBPF concentrations.At 60 DAP,the gas exchange variables during both assessment periods declined with an increase in KBPF concentration.Significant differences as a result of KBPF applications were found only at the start of the assessments(34 DAP)for both WUE and for IWUE.Leaf‘greenness’(SPAD reading)at 47 days showed a quadratic relationship in both periods.The variables of chlorophyll fluorescence showed a linear response at 34 DAP and a quadratic response 60 DAP.KBPF application increased height and diameter growth in plants treated with 3%KBPF but this response was not associated with photochemical efficiency and photosynthetic carbon assimilation values on a single-leaf basis.The best performance among the variables was provided by 3%KBPF application.

Production and quality of eucalyptus mini-cuttings using kaolin-based particle films

Considering the expansion of forest plantations over the Brazilian territory and the imminent increase in air temperatures due to global warming,the search for technologies that ensure high levels of productivity and high quality plants in clonal nurseries is essential.Applying kaolin-based particle films(KBPF)has been used as a physical barrier to reduce the negative effects of excessive solar radiation and adverse temperatures.The effects of KBPF on production and physiological quality of eucalyptus mini-cuttings were evaluated during two different seasons.A randomized block design was used,consisting of five treatments and four replications.Five concentrations(0,3%,5%,7%,and 10%)were tested here and six weekly replicates of each concentration was applied.The different kaolin concentrations and seasonal variations resulted in a quadratic response of the leaf SPAD reading during both daily evaluation periods.KBPF applications resulted in a quadratic response of photochemical efficiency in the morning period,and an increasing specific leaf weight linear response,and during the dry season,the different kaolin concentrations resulted in a bud length quadratic response.The results indicated that the kaolin application maintained the production and yield index statistically equal between weekly KBPF applications,improving photochemical efficiency,leaf thickness,SPAD reading,and bud length.The use of KBPF could reduce the intervals between collections of mini-cuttings and increase nursery yields in environments that present high temperatures.