Foliar Area Research Articles

Evolutionary Adaptations of Palmer Amaranth (Amaranthus palmeri) to Nitrogen Fertilization and Crop Rotation History Affect Morphology and Nutrient-Use Efficiency

Palmer amaranth control has become a major challenge for multiple cropping systems across the southeastern and midwestern United States. Despite extensive research on herbicide-resistance evolution, little research has been done exploring how Palmer amaranth might also be evolving other adaptive traits in response to different selection forces present in agricultural fields and the enrichment of soils with nutrients such as nitrogen. The objective of the present study was to determine whether Palmer amaranth populations have evolved different morphology and growth patterns in response to glyphosate use and fertilization history. Ten Palmer amaranth populations, including glyphosate-resistant (GR) and glyphosate-susceptible (GS) populations, were collected from different cropping systems with histories of high and low nitrogen fertilization in the states of Florida and Georgia. All populations were grown in pots filled with soil fertilized with either 0 or 40 kgNha−1, and their response to nitrogen was compared for morphological, growth, and nutrient-use traits. Populations differed in how they modified their morphology and growth in response to N, with major differences in traits such as foliar area, branch production, leaf shape, and canopy architecture. Populations with high nitrogen-fertilization histories had higher (>43%) nutrient-use efficiency (NUE) than populations with low nitrogen-fertilization histories. Similarly, GR populations have evolved higher NUE (>47%) and changed canopy architecture more than GS populations in response to nitrogen fertilization. The results of the present study highlight the importance of paying more attention to adaptations to cultural practices that might increase weediness and how genetic changes in traits involved in morphology and metabolism might favor compensatory mechanisms increasing the fitness of the population carrying herbicide-resistant traits.

Mapping local and global variability in plant trait distributions

Our ability to understand and predict the response of ecosystems to a changing environment depends on quantifying vegetation functional diversity. However, representing this diversity at the global scale is challenging. Typically, in Earth system models, characterization of plant diversity has been limited to grouping related species into plant functional types (PFTs), with all trait variation in a PFT collapsed into a single mean value that is applied globally. Using the largest global plant trait database and state of the art Bayesian modeling, we created fine-grained global maps of plant trait distributions that can be applied to Earth system models. Focusing on a set of plant traits closely coupled to photosynthesis and foliar respiration-specific leaf area (SLA) and dry mass-based concentrations of leaf nitrogen ([Formula: see text]) and phosphorus ([Formula: see text]), we characterize how traits vary within and among over 50,000 [Formula: see text]-km cells across the entire vegetated land surface. We do this in several ways-without defining the PFT of each grid cell and using 4 or 14 PFTs; each model's predictions are evaluated against out-of-sample data. This endeavor advances prior trait mapping by generating global maps that preserve variability across scales by using modern Bayesian spatial statistical modeling in combination with a database over three times larger than that in previous analyses. Our maps reveal that the most diverse grid cells possess trait variability close to the range of global PFT means.

Efeito da aplicação de piraclostrobina no crescimento inicial de café arábica em diferentes disponibilidades hídricas

<p>Objetivou-se com este estudo investigar o efeito da piraclostrobina no crescimento inicial de plantas de <em>Coffea arabica</em> L. submetidas ou não ao déficit hídrico, utilizando para isso, a avaliação das características da matéria seca total (MST), da parte aérea (MSPA) e da raiz (MSR), área foliar (AF), altura e diâmetro do coleto, além da eficiência no uso da água de produtividade (EUA<sub>p</sub>) em plantas cultivadas a 100 (-DH, sem déficit hídrico) e 30% (+DH, com déficit hídrico) de água disponível no substrato. De acordo com os resultados obtidos, foi verificado que a aplicação de piraclostrobina nas plantas submetidas a -DH, principalmente na maior concentração (1,4 g/L), favoreceu o incremento da MST, da MSPA, da MSR, da área foliar, altura, diâmetro do coleto e da EUA<sub>p</sub>. Sob déficit hídrico (+DH), o crescimento das plantas não foi beneficiado pela aplicação de piraclostrobina, independente da concentração utilizada, evidenciando a necessidade do controle de água adequado como estratégia de manejo para a produção.</p>

Evaluation of rhizobacteria in upland rice in Brazil: growth promotion and interaction of induced defense responses against leaf blast (Magnaporthe oryzae)

Blast and the initial vigor of upland rice plants are the main challenges facing rice crops in Brazilian no-tillage systems. The aim of this study was to evaluate the growth promotion and interactions of defense responses against Magnaporthe oryzae in rice plants treated with rhizobacteria Bacillus sp. (BRM 32110) and Serratia sp. (BRM 32114). The seeds of the rice were microbiolized, and 14 days after the plants emerged, the soil was drenched with rhizobacterial suspensions. Growth promotion was evaluated by root and shoot biomass, root and shoot length, foliar area, and nitrate reductase (NR) activity. The defense response was evaluated by quantification of the rice blast severity (RBS), disease progress, pathogenesis-related protein (PRP) activity, and salicylic acid content (SA). The length and biomass of the roots and shoots and the foliar area of the plants treated with BRM 32114 isolate increased; however, the NR activity was 43% lower compared to the control. Both isolates reduced the severity and progress of the disease. Principal component analysis showed that RBS, β-1,3-glucanase (GLU), peroxidase (POX), and phenylalanine ammonia lyase (PAL) were the main sources of the first components of variance, whereas lipoxygenase (LOX) and SA were the main sources of the second components and were negatively correlated. Serratia sp. isolate BRM 32114 can be used as a growth-promoting agent and has potential for inducing resistance in rice plants. The results suggest that the interaction among the levels and timing of the PRP activity and the levels of SA play important roles in the defense responses against M. oryzae.

Oviposition preference and larval performance and behavior of Trichoplusia ni (Lepidoptera: Noctuidae) on host and nonhost plants

We investigated the female oviposition preference and larval performance and behavior of Trichoplusia ni (Hubner) on cabbage, tomato, soybean (host plants), and wormseed (nonhost plant) in laboratory experiments. In addition, we investigated the role of trichomes in the oviposition of females. Females oviposited more often on cabbage than on tomato, soybean, or wormseed plants. Tomato was the second most preferred plant, followed by soybean and wormseed. Neonate larvae gained more weight on cabbage and tomato than on soybean or wormseed, while second-instar larvae grew better on cabbage than on tomato, soybean, or wormseed. The least growth of neonate larvae occurred on wormseed plants. The orientation of neonate and second-instar larvae to cabbage, tomato, soybean, and wormseed did not differ significantly. Neonate larvae settled equally on leaf discs of cabbage, tomato, soybean, and wormseed, while most second-instar larvae settled on leaf discs of cabbage in comparison with the other plants after 24 h of release. The foliar area consumed by neonate larvae was quite similar among plants, but second-instar larvae consumed more cabbage than tomato, soybean, or wormseed. Comparing different types of leaves, females oviposited more often on mature than young leaves of tomato, soybean, and wormseed. In contrast, females did not show any preference for ovipositing on young or mature leaves of cabbage. In general, we found that the density or length of nonglandular and glandular trichomes of tomato, soybean, and wormseed plants negatively affected oviposition of T. ni females.

Physiological Assessment of Water Stress in Potato Using Spectral Information.

Water stress in potato (Solanum tuberosum L.) causes considerable losses in yield, and therefore, potato is often considered to be a drought sensitive crop. Identification of water deficit tolerant potato genotypes is an adaptation strategy to mitigate the climatic changes that are occurring in the Cundiboyacense region in Colombia. Previous studies have evaluated potato plants under water stress conditions using physiological analyses. However, these methodologies require considerable amounts of time and plant material to perform these measurements. This study evaluated and compared the physiological and spectral traits between two genotypes, Diacol Capiro and Perla Negra under two drought levels (10 and 15 days without irrigation from flowering). Reflectance information was used to calculate indexes which were associated with the physiological behavior in plants. The results showed that spectral information was correlated (ρ < 0.0001) with physiological variables such as foliar area (FA), total water content (H2Ot), relative growth rate of potato tubers (RGTtub), leaf area ratio (LAR), and foliar area index (AFI). In general, there was a higher concentration of chlorophyll under drought treatments. In addition, Perla Negra under water deficit treatments did not show significant differences in its physiological variables. Therefore, it could be considered a drought tolerant genotype because its physiological performance was not affected under water stress conditions. However, yield was affected in both genotypes after being subject to 15 days of drought. The results suggested that reflectance indexes are a useful and affordable approach for potato phenotyping to select parent and segregant populations in breeding programs.

Tomato growth analysis across three cropping systems

ABSTRACT The objective of this work was to analyze the growth of the Upiã tomato cultivar in the Vertical, Crossed Fence and Viçosa cultivation systems, in order to obtain explanations for the productive gains achieved in the Viçosa system. The experiment was conducted in Viçosa, Minas Gerais State, Brazil, from August 21st to December 5th, 2012, in the scheme of subdivided plots, being the plots represented by the cultivation systems: Vertical, using tape, 1.0×0.5 m spacing; Crossed Fence, staked with bamboo, 1.0x0.5 m spacing; and Viçosa, using tape, 2.0x0.2 m spacing. The subplots were composed by the sampling times of the plants: 15, 30, 45, 60 and 75 days after transplanting. The experimental design was in randomized blocks, with four replications. Each plot was composed by three lines of 10 plants, making a total of 30 plants per plot, being evaluated the four central plants of each plot. We evaluated the dry matter of leaves (MSF), stem (MSC), inflorescences (MSI), fruits (MSFr) and total (MST). Using the foliar area index, measured by digital scanners and the previously obtained dry masses, we determined the physiological growth indices: foliar area index (IAF), specific foliar area (AFE), relative growth rate (TCR), and net assimilation rate (TAL). The Viçosa system altered the growth pattern of the tomato, quantified by the growth analysis, in comparison to Crossed and Vertical Fences. The prolongation of the second growth phase for the dry matter of fruits could possibly explain the productive gains obtained in the Viçosa system. Additional studies are required in order to clarify the relationship between the duration of the second phase of fruit dry matter growth, the physiological indexes AFE, IAF and TAL with the size and fruit yield of the tomato.

Top canopy nitrogen allocation linked to increased grassland carbon uptake in stands of varying species richness

Models predict that vertical gradients of foliar nitrogen (N) allocation, increasing from bottom to top of plant canopies, emerge as a plastic response to optimise N utilisation for carbon assimilation. While this mechanism has been well documented in monocultures, its relevance for mixed stands of varying species richness remains poorly understood. We used 21 naturally assembled grassland communities to analyse the gradients of N in the canopy using N allocation coefficients (KN) estimated from the distribution of N per foliar surface area (KN-F) and ground surface area (KN-G). We tested whether: 1) increasing plant species richness leads to more pronounced N gradients as indicated by higher KN-values, 2) KN is a good predictor of instantaneous net ecosystem CO2 exchange and 3) functional diversity of leaf N concentration as estimated by Rao’s Q quadratic diversity metric is a good proxy of KN. Our results show a negative (for KN-G) or no relationship (for KN-F) between species richness and canopy N distribution, but emphasize a link (positive relationship) between more foliar N per ground surface area in the upper layers of the canopy (i.e. under higher KN-G) and ecosystem CO2 uptake. Rao’s Q was not a good proxy for either KN.

CORRELATION AMONG DAMAGES CAUSED BY YELLOW BEETLE, CLIMATOLOGICAL ELEMENTS AND PRODUCTION OF GUAVA ACCESSES GROWN IN ORGANIC SYSTEM

ABSTRACT The objective of this research was evaluate the damage caused by the yellow beetle on 85 guava accessions and correlations of the damage with the climatological elements and the production of fruit in an orchard of guava conducted in organic system. Ten leaves by access were analyzed containing the injury of insect attack. Each leaf had its foliar area measured by leaf area meter and, after obtaining the total area, the leaf was covered with duct tape, and measure again. The averages were compared by Scott-Knott test at 5% probability. The 15 accessions with highest average damage had the data submitted to the correlation with the minimum and maximum temperature, precipitation and relative humidity. The production was obtained by the number of fruits/plant. The damages are negatively correlated with the mean relative humidity of 7:00h (local time) in the period of 14 days prior to the assessments, and negatively affect production. The accessions Saito, L4P16, Monte Alto Comum 1 and L5P19 are promising in organic agriculture, for presenting good production and minor damage to insect attack, when compared to others.

Uso potencial de lixiviados y tés de vermicompost en el control del ojo de gallo del cafeto &lt;i&gt;Mycena citricolor&lt;/i&gt;

El objetivo de este trabajo fue evaluar el efecto de tés y lixiviados de vermicompost obtenidos a partir de diferentes materiales de origen animal y vegetal, sobre la supresión del hongo M. citricolor en hojas de cafeto (Coffea arabica) en condiciones de laboratorio. A las hojas de cafeto se les aplicó tés de vermicompost de diferentes estiércoles, de broza de café y de una mezcla de lixiviados de vermicompost de broza de café y estiércol bovino, previo a la inoculación con el hongo M. citricolor. Se evaluó la incidencia (porcentaje de hojas enfermas) y severidad (porcentaje de área foliar dañada), el número de lesiones con gemas y de estructuras reproductivas del hongo (gemas). Se observó diferencias dentro de cada grupo de abono, así, cuando se aplicaron tés a base de vermicompost de estiércoles, se encontró que el té de vermicompost de estiércol caprino favoreció el desarrollo de los síntomas de la enfermedad, pues presentó un 16,5% más de área foliar dañada y un mayor número de lesiones con gemas, comparado con el tratamiento testigo; por el contrario el tratamiento con té de vermicompost de estiércol bovino presentó un 50% menos de hojas enfermas que el tratamiento testigo y no presentó lesiones con gemas. El uso de tés de vermicompost de broza de café aumentó el desarrollo de la enfermedad con un porcentaje de hojas enfermas y del área foliar dañada superior al testigo en más de un 20%. En el caso de los tratamientos con lixiviados de vermicompost, aquellos a base de vermicompost de broza, no presentaron lesiones con formación de gemas.

Lysinibacillus sphaericus plant growth promoter bacteria and lead phytoremediation enhancer with Canavalia ensiformis

Lysinibacillus sphaericus is known for its great larvicidal activity against mosquito larvae and toxic metal resistance, but knowledge about its possible activity in soil is scarce and poor. Nevertheless, in the genome of some strains have been reported genes of nitrogen cycle. Seven L. sphaericus strains were tested as nitrogen fixing bacteria, nitrifying bacteria, and indoleacetic acid producer. Subsequently a consortium was formulated using the best strains (CBAM5, III(3)7, OT4b.31, and OT4b.49) to evaluate its effect in Canavalia ensiformis growth and lead phytoremediation. All L. sphaericus strains were able to fix nitrogen (0.61–1.47 mg/L of ammonium), nitrify (0.26–0.7 mg/L of nitrate), and produce IAA (3.3–5.5 µg/mL in L‐tryptophan media and 0.3–1.1 µg/mL in trypticase broth). They also promoted shoot length, root length, foliar area, and leaf number in C. ensiformis, enhanced lead bioaccumulation in the root reaching a removal of 40% of lead in greenhouse experiment, and increased nitrate content in soil twofold in contrast to the control in field experiment. Therefore, L. sphaericus could be a key organism in the formulation of biofertilizers, as it shows potential in the phytoremediation processes, in crop plant nutrition, and growth in low nutrient polluted soils, then is a plant growth promoter bacteria (PGPB). © 2017 American Institute of Chemical Engineers Environ Prog, 37: 276–282, 2018

GRAFT TAKES OF TOMATO ON OTHER SOLANACEOUS PLANTS

ABSTRACT This paper aimed to assess tomato grafting on different solanaceous species through two grafting methods. Scions were cut from cultivar Santa Cruz Kada seedlings. A fully randomized experimental design was carried out with treatments in a 9 x 2 factorial scheme. As rootstocks, four accessions of mini-tomatoes (0224-53, RVTC 57, RVTC 20 and 6889-50 - Solanum lycopersicum L); two species of wild tomato (Solanum habrochaites var hirsutum ‘PI-127826’ and Solanum pennellii ‘LA716’); other two tomato species [Solanum, cocona (Solanum sessiliflorum) and physalis (Physalis peruviana)] and a control with cultivar Santa Cruz Kada (auto-graft) rootstocks were used. In addition, two grafting methods were evaluated full cleft and approach graft. Fifteen days after grafting, plants were assessed for graft-take percentage; root length; plant height; leaf number; foliar area; root, stem and leaf dry matter; and ratio between shoot and root dry matter. Based on the results, we may state rootstock and grafting interaction had effect on both graft -take rate and plant development. Overall, the studied plants should be recommended as rootstock, except for 6889-50 mini-tomato (S. lycopersicum L.) and S. pennellii. Full cleft grafting was most suitable for cocona and physalis, while the approach method showed better results for the mini-tomato accessions 0224-53, RVTC 57 and RVTC 20, as well as for S. habrochaites.

Application of Arbuscular Mycorrhizal Fungi during the Acclimatization of Alpinia purpurata to Induce Tolerance to Meloidogyne arenaria.

An experiment was conducted to evaluate the tolerance of micropropagated and mycorrhized alpinia plants to the parasite Meloidogyne arenaria. The experimental design was completely randomized with a factorial arrangement of four inoculation treatments with arbuscular mycorrhizal fungi (AMF) (Gigaspora albida, Claroideoglomus etunicatum, Acaulospora longula, and a non-inoculated control) in the presence or absence of M. arenaria with five replicates. The following characteristics were evaluated after 270 days of mycorrhization and 170 days of M. arenaria inoculation: height, number of leaves and tillers, fresh mass of aerial and subterranean parts, dry mass of aerial parts, foliar area, nutritional content, mycorrhizal colonization, AMF sporulation, and the number of galls, egg masses, and eggs. The results indicated a significant interaction between the treatments for AMF spore density, total mycorrhizal colonization, and nutrient content (Zn, Na, and N), while the remaining parameters were influenced by either AMF or nematodes. Plants inoculated with A. longula or C. etunicatum exhibited greater growth than the control. Lower N content was observed in plants inoculated with AMF, while Zn and Na were found in larger quantities in plants inoculated with C. etunicatum. Fewer galls were observed on mycorrhized plants, and egg mass production and the number of eggs were lower in plants inoculated with G. albida. Plants inoculated with A. longula showed a higher percentage of total mycorrhizal colonization in the presence of the nematode. Therefore, the association of micropropagated alpinia plants and A. longula enhanced tolerance to parasitism by M. arenaria.

Screening of cadmium and copper phytoremediation ability of Tagetes erecta, using biochemical parameters and scanning electron microscopy-energy-dispersive X-ray microanalysis.

Tagetes erecta thrived in phytotoxic levels of cadmium (Cd; 50-300 mg kg-1 ) and copper (Cu; 150-400 mg kg-1 ) for 21 d. It accumulated high metal contents in its above-ground tissues (3675 mg Cd kg-1 dry wt and 3948 mg Cu kg-1 dry wt) and showed greater root to shoot translocation and a high extraction coefficient, all of which pointed toward its potential as a hyperaccumulator. Both Cd stress and Cu stress reduced the plant biomass, foliar area, and number. In addition, there were significant declines in pigment contents as well as boosts in lipid peroxidation levels. However, the plant triggered a number of stress-mitigation strategies to abate reactive oxygen species formed as a result of Cd/Cu excess, mostly via significant augmentation of superoxide dismutase, catalase, glutathione peroxidase, and ascorbate peroxidase activities. Though the root and leaf anatomy revealed some signs of toxic symptoms at 50 mg Cd kg-1 and at 150 mg Cu kg-1 , as evidenced by scanning electron microscopy, the root showed maximum tolerance, with tolerance indexes of 85.4% and 91.7%, respectively. Energy-dispersive X-ray microanalysis showed specific Ca2+ signals in both root and stomata, which could be associated with a specific signaling pathway leading to increased root metal uptake and stomatal closure. Environ Toxicol Chem 2017;36:2533-2542. © 2017 SETAC.

Impacts of future deforestation and climate change on the hydrology of the Amazon Basin: a multi-model analysis with a new set of land-cover change scenarios

Abstract. Deforestation in Amazon is expected to decrease evapotranspiration (ET) and to increase soil moisture and river discharge under prevailing energy-limited conditions. The magnitude and sign of the response of ET to deforestation depend both on the magnitude and regional patterns of land-cover change (LCC), as well as on climate change and CO2 levels. On the one hand, elevated CO2 decreases leaf-scale transpiration, but this effect could be offset by increased foliar area density. Using three regional LCC scenarios specifically established for the Brazilian and Bolivian Amazon, we investigate the impacts of climate change and deforestation on the surface hydrology of the Amazon Basin for this century, taking 2009 as a reference. For each LCC scenario, three land surface models (LSMs), LPJmL-DGVM, INLAND-DGVM and ORCHIDEE, are forced by bias-corrected climate simulated by three general circulation models (GCMs) of the IPCC 4th Assessment Report (AR4). On average, over the Amazon Basin with no deforestation, the GCM results indicate a temperature increase of 3.3 °C by 2100 which drives up the evaporative demand, whereby precipitation increases by 8.5 %, with a large uncertainty across GCMs. In the case of no deforestation, we found that ET and runoff increase by 5.0 and 14 %, respectively. However, in south-east Amazonia, precipitation decreases by 10 % at the end of the dry season and the three LSMs produce a 6 % decrease of ET, which is less than precipitation, so that runoff decreases by 22 %. For instance, the minimum river discharge of the Rio Tapajós is reduced by 31 % in 2100. To study the additional effect of deforestation, we prescribed to the LSMs three contrasted LCC scenarios, with a forest decline going from 7 to 34 % over this century. All three scenarios partly offset the climate-induced increase of ET, and runoff increases over the entire Amazon. In the south-east, however, deforestation amplifies the decrease of ET at the end of dry season, leading to a large increase of runoff (up to +27 % in the extreme deforestation case), offsetting the negative effect of climate change, thus balancing the decrease of low flows in the Rio Tapajós. These projections are associated with large uncertainties, which we attribute separately to the differences in LSMs, GCMs and to the uncertain range of deforestation. At the subcatchment scale, the uncertainty range on ET changes is shown to first depend on GCMs, while the uncertainty of runoff projections is predominantly induced by LSM structural differences. By contrast, we found that the uncertainty in both ET and runoff changes attributable to uncertain future deforestation is low.

Variable salinity responses of 12 alfalfa genotypes and comparative expression analyses of salt-response genes

Twelve alfalfa genotypes that were selected for biomass under salinity, differences in Na and Cl concentrations in shoots and K/Na ratio were evaluated in this long-term salinity experiment. The selected plants were cloned to reduce genetic variability within each genotype. Salt tolerance (ST) index of the genotypes ranged from 0.39 to 1. The most salt-tolerant genotypes SISA14-1 (G03) and AZ-90ST (G10), the top performers for biomass, exhibited the least effect on shoot number and height. SISA14-1 (G03) accumulated low Na and Cl under salinity. Most genotypes exhibited a net reduction in shoot Ca, Mg, P, Fe, and Cu, while Mn and Zn increased under salinity. Salinity reduced foliar area and stomatal conductance; while net photosynthetic rate and transpiration were not affected. Interestingly, salinity increased chlorophyll and antioxidant capacity in most genotypes; however neither parameter correlated well to ST index. Salt-tolerant genotypes showed upregulation of the SOS1, SOS2, SOS3, HKT1, AKT1, NHX1, P5CS1, HSP90.7, HSP81.2, HSP71.1, HSPC025, OTS1, SGF29 and SAL1 genes. Gene expression analyses allowed us to classify genotypes based on their ability to regulate different components of the salt tolerance mechanism. Pyramiding different components of the salt tolerance mechanism may lead to superior salt-tolerant alfalfa genotypes.

Recycling organic wastes to agricultural land as a way to improve its quality: A field study to evaluate benefits and risks

A field study was established to assess the effects of a sewage sludge (SS), a mixed municipal solid waste compost (MMSWC) and a compost produced from agricultural wastes (AWC), in a Vertisol, using Lolium multiflorum L. The amendments were applied for two consecutive years: 6, 12 and 24t dry matter ha−1 for SS, and the amendment doses for MMSWC and AWC were calculated to deliver the same amount of organic matter (OM) per unit area. The amendments had significant beneficial effects on some soil properties (e.g. soil OM, NKjeldahl, extractable P and K), and on plant productivity parameters (e.g. biomass yield, chlorophyll, foliar area). For instance, soil OM increased from 0.78% to 1.71, 2.48 and 2.51%, after two consecutive years of application of 24t dry matter ha−1 of SS, MMSWC and AWC, respectively, while the plant biomass obtained increased from 7.75tha−1 to 152.41, 78.14 and 29.26tha−1, for the same amendments. On the plant, effects were more pronounced for SS than for both compost applications, a consequence of its higher capacity to provide N to the plant in a readily available form. However, after two years of application, the effects on soil properties were more noticeable for both composts, as their OM is more resistant to mineralization, which endures their beneficial effects on soil. Cadmium, Cr, Ni and Pb pseudo-total concentrations, were not affected significantly by the application of the organic wastes to soil, in all tested doses, neither their extractability by 0.01M CaCl2. On the contrary, Cu and Zn pseudo-total concentrations increased significantly in the second year of the experiment, following the application of the higher rate of MMSWC and AWC, although their extractability remained very low (<0.5% of their pseudo-total fraction). Trace elements concentrations in the aboveground plant material were lower than their maximum tolerable levels for cattle, used as an indicator of risk of their entry into the human food chain. Despite these results, it is interesting to note that the SS promoted a significant increase in the foliar concentrations of Cu, Ni and Zn that did not happen in composts application, which can be explained by the reduction of the soil pH, as a consequence of SS degradation in soil. Concluding, if this type of organic wastes were to be used in a single application, the rate could be as high as 12 or even 24tha−1, however, if they are to be applied in an annual basis, the application rates should be lowered to assure their safe application (e.g. to 6tha−1). Moreover, it is advisable to use more stable and mature organic wastes, which have longer lasting positive effects on soil characteristics.

The Efficacy of a Practical Activity in the Construction of Knowledge of the Concepts of Species and Phenotypic Plasticity Using the Boldo Mirim (&amp;lt;i&amp;gt;Plectranthus neochilus&amp;lt;/i&amp;gt; Schltr.)

The analyses efficacy of a practical activity addressing the measure of morphological characteristics of Boldo Mirim (Miniature Boldo), (Plectranthus neochilus Schltr.) which were cultivated in two conditions of solar intensity (50% and 100%), involved two professors and 7 students who participated at different ways in planning, performing and evaluating the results. This activity was carried out in 49 students matriculated in the discipline Botany II of 1st semester of the Biological Sciences course of UFF. The objective of the present study was to foment the construction of a significant learning about concept of specie and phenotypic plasticity. To perform the measurements on the leaves: 1) the foliar areas by two methods (weigh and counting); 2) the internode distance; and 3) the presence of trichome, two types of papers (baking and millimetric) and basic equipment such as manual calibration caliper (mm), precision analytical balance (0.001 g) and a monocular stereoscope (40×) were provided. It was verified that with the reduction in the availability of solar light, the Boldo Mirim increases its leaf area and the distance internodes for the best use of the luminosity in the photosynthetic process, whereas in conditions of full sunshine this plant invests less in leaf area and reduces the distance between leaves that are practically superimposed to avoid stress due to excess of light. After following the proposed protocol, the questionnaire with 12 questions about the plant’s characteristics, the concepts of species and of phenotypic plasticity, and the effectiveness of the practical activity were applied to the 14 groups of 3 to 4 students from the total of 49 ones. The correlation coefficients obtained from the comparison of the two methods used to measure the foliar area (weight and counting) was positive and significant for Branch type 1 (from plant raised at 100% of solar intensity: r = 0.806, n = 10; p ≤ 0.005) and for Branch type 2 (from plant raised at 50% of solar intensity: r = 0.755, n = 10; p ≤ 0.005) as well. These results revealed that the proposal of the practice reached its goals. However, the critics of the 49 target students fell mainly on the restriction of the available time to the practical activity. In conclusion, the activity involvement revealed that the practical activity achieved its purpose. Thus, all the 56 students involved were able to construct the knowledge about the scientific methods, the concepts of species and phenotypic plasticity, and the therapeutic applicability of the Mirim Boldo, within a critical vision of the teaching-learning process.

FOTOSSÍNTESE EM DIFERENTES GENÓTIPOS DE FEIJOEIRO

RESUMO: O objetivo do presente trabalho foi avaliar o efeito de taxa de fotossíntese (TF), condutância estomática (CE), matéria seca total de raiz e parte aérea, área foliar e clorofila a, clorofila b e clorofila total, sobre a produtividade em genótipos de feijoeiro. Foram realizados dois experimentos, um em campo (CP), no município de Cristalina – GO, e outro em casa de vegetação (CV), na Estação Experimental da Universidade de Brasília - DF, entre Agosto e Novembro de 2002... Na avaliação da TF e CE, utilizou-se o analisador portátil de gás por infravermelho. O teor de clorofila foi determinado pelo método de extração acetona 80% e leitura em espectrofotômetro. A biomassa vegetal foi determinada pelo método da secagem e pesagem. A área foliar foi determinada utilizando-se o medidor de área foliar. Os genótipos apresentaram valores diferenciados para a maioria dos parâmetros avaliados, tanto em campo como em casa de vegetação. Não houve correlação na maioria das combinações que envolveram épocas de avaliação, local de experimento (campo e casa de vegetação) e genótipos avaliados. O teor de clorofila não se correlacionou com qualquer dos parâmetros analisados. A taxa de fotossíntese na fase R7 apresentou correlação positiva (r = 0,627) com a produção de grão. Os demais fatores não se correlacionaram. A fase R7 foi a melhor época para avaliar o efeito da fotossíntese na produção de grãos. PALAVRAS-CHAVE: Área foliar, Clorofila, Condutância estomática, Matéria seca, Produtividade, Taxa de fotossíntese.

Aerially Released Spray Penetration in a Tall Coniferous Forest Canopy

An aerial spray deposition project was designed to evaluate aerial application to an eastern hemlock (Tsuga canadensis) canopy to combat hemlock woolly adelgid (Adelges tsugae). This adelgid, residing in the forest canopy at the nodes of branchlets, offers a difficult target. The study collected 1840 deposition samples on live and artificial collectors (not including auxiliary studies) positioned to evaluate canopy penetration of spray applied from above the canopy by helicopter. The results of the study show that canopy penetration is achieved with 3% to 8% of applied material (corrected for foliar area) deposited on the lowest samplers and 6% to 12% deposited on samplers positioned in hard-to-reach locations in the mid-canopy. The study also suggests that it might not be necessary to apply as fine a droplet distribution (release DV0.5 values of 87 and 108?m are used in most of the trials described here) as originally thought to achieve coverage in this deep canopy. A second article will compare these data to existing models.