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Weight-length relations of fishes are useful for estimation of biomass from length observations, e.g., in fisheries or conservation research. Here we provide some guidance to authors of such papers, in order to facilitate the publication and review process

Global biogeochemical models have improved dramatically in the last decade in their representation of the biosphere. Although leaf area data are an important input to such models and are readily available globally, global root distributions for modeling water and nutrient uptake and carbon cycling have not been available. This analysis provides global distributions for fine root biomass, length, and surface area with depth in the soil, and global estimates of nutrient pools in fine roots. Calculated root surface area is almost always greater than leaf area, more than an order of magnitude so in grasslands. The average C:N:P ratio in living fine roots is 450:11:1, and global fine root carbon is more than 5% of all carbon contained in the atmosphere. Assuming conservatively that fine roots turn over once per year, they represent 33% of global annual net primary productivity.

For 76 annual, biennial, and perennial species common in the grasslands of central Minnesota, USA, we determined the patterns of correlations among seven organ-level traits (specific leaf area, leaf thickness, leaf tissue density, leaf angle, specific root length, average fine root diameter, and fine root tissue density) and their relationships with two traits relating to growth form (whether species existed for part of the growing season in basal, non-caulescent form and whether species were rhizomatous or not). The first correlation of traits showed that grasses had thin, dense leaves and thin roots while forbs had thick, low-density leaves and thick roots without any significant differences in growth form or life history. The second correlation of traits showed a gradient of species from those with high-density roots and high-density erect leaves to species with low-density roots and low-density leaves that were held parallel to the ground. High tissue density species were more likely to exist as a basal rosette for part of the season, were less likely to be rhizomatous, and less likely to be annuals. We examined the relationships between the two axes that represent the correlations of traits and previously collected data on the relative abundance of species across gradients of nitrogen addition and disturbance. Grasses were generally more abundant than forbs and the relative abundance of grasses and forbs did not change with increasing nitrogen addition or soil disturbance. High tissue density species became less common as fertility and disturbance increased.

Cleft grafting methods were applied in order to evaluate the effect of grafting on tomato fruit yield and quality. The tomato cultivars used as scions were Yeni Talya, Swanson and Beri. The cultivars Beaufort and Arnold were used as rootstocks. The following characteristics of grafted and nongrafted plants were recorded: fruit index, number of fruits/truss, fruit weight, fruit yield, dry matter, pH, concentration of soluble solids, titratable acidity, concentrations of total sugar, lycopene and vitamin C. The results showed that fruit yield and fruit index, number of fruits/truss and fruit weights were improved by grafting. Fruit quality, measured in terms of concentrations of dry matter, soluble solids, total sugar, and vitamin C, was lower in grafted plants than in nongrafted ones. No significant difference in lycopene level and pH was found. Titratable acidity was improved by grafting. A positive effect of grafting was recorded when Beaufort was used as rootstock. These results showed that grafting could be an advantageous alternative in tomato production.

ABSTRACT Leaf area is an essential variable for the quantification of other important leaf characteristics in physiological studies of plants, such as normalized photosynthetic rate and normalized phosphorus content. That is one of the reasons for the need of fast and accurate methods to estimate leaf area. The objective of this work was to fit linear or non-linear regression models to predict the individual leaf area of six species of forage legumes, based on digital images analyzed with the package LeafArea, R software. In a field experiment, 100 leaves were randomly collected from the following species: Crotalaria juncea (L.), Canavalia ensiformis (L.), Cajanus cajan (L.), Dolichos lablab (L.), Mucuna cinereum (L.), and Mucuna aterrima (Piper & Tracy) Merr., in which the central leaflet length and width were measured. Afterwards, digital images of each leaf were processed in R software for leaf area estimation. These estimates were used to fit leaf area prediction models; in fact, seventy leaves were used to fit the models; the rest of them were used for model validation. For the six species, the complete second-degree polynomial model, or derivative submodels, can be used to predict leaf area as a function of length and width of the central leaflet, presenting R² above 0.98 and percentage absolute mean error below 9%. In these models, the effect of leaf width is generally greater than the leaf length. The R package LeafArea showed to be a very efficient tool for the estimation of leaf area through the execution of the software ImageJ, with high precision and easy calibration. RESUMO A área foliar é uma variável essencial para a quantificação de outras importantes características foliares em estudos fisiológicos de plantas, como taxa fotossintética e teor de fósforo, normalizados por área. Essa é uma das razões para a necessidade de métodos rápidos e precisos para estimar a área foliar. O objetivo deste trabalho foi ajustar modelos de regressão linear ou não linear para predizer a área foliar de seis espécies de leguminosas forrageiras, a partir de imagens digitais analisadas com o pacote LeafArea, software R. Em um experimento de campo, foram coletadas aleatoriamente 100 folhas das seguintes espécies: Crotalaria juncea (L.), Canavalia ensiformis (L.), Cajanus cajan (L.), Dolichos lablab (L.), Mucuna cinereum (L.), e Mucuna aterrima (Piper & Tracy) Merr., nas quais foram medidos o comprimento e a largura do folíolo central. Posteriormente, imagens digitais de cada folha foram processadas no software R para estimativa da área foliar. Essas estimativas foram usadas para ajustar modelos de predição de área foliar; de fato, setenta folhas foram usadas para ajustar os modelos; o restante delas foi usado para validação do modelo. Para as seis espécies, o modelo polinomial completo de segundo grau, ou submodelos derivados, pode ser usado para predizer a área foliar em função do comprimento e largura do folíolo central, apresentando R² acima de 0,98 e porcentagem de erro médio absoluto abaixo de 9%. Nestes modelos, o efeito da largura da folha é geralmente maior que o comprimento da folha. O pacote R LeafArea mostrou-se uma ferramenta muito eficiente para a estimativa da área foliar através da execução do software ImageJ, com alta precisão e fácil calibração.

Root length and diameter distribution are important characteristics to be considered when describing and comparing root systems. Root length and root-diameter distribution may be obtained in two ways: by microscopical measurements, which are laborious, or by computerised analysis, which is fast but sensitive to the scanning protocol. Although scanning protocols vary widely between laboratories, papers rarely report the details. Using two commercially available root analysis software packages (Delta-T Scan and WinRHIZO), we performed a sensitivity analysis of scanning protocols for estimating root length and diameter distribution. The results are shown graphically, rather than numerically, because the interactions between different parameters in the overall scanning protocol are most clearly illustrated by the shape of the curves. The present analysis clearly demonstrated the sensitivity of the two scanning methods with regard to staining period, maximum root density, scanning resolution and transformation threshold. For example, estimating the root-diameter distribution versus measuring root length, puts opposite constraints on the transformation threshold settings. We suggest the following settings for the most sensitive parameters: a staining period of 24 h, a root density of less than 0.5 mm root per mm 2 surface, a resolution of 400 dpi and the automatic threshold for WinRHIZO and a brightness of 200 for Delta-T Scan. According to this protocol, comparison of computerised analyses with microscopic measurements showed good total root length and diameter distribution agreement for three contrasting root systems. We suggest to always start with the present protocol when studying other species. If validation indicates that the proposed scanning protocol needs to be modified for other species, the present sensitivity analysis may be used as a guideline for changing the most critical parameters. Similarly, the use of another stain than neutral red may also require modifications of the scanning protocol. In general, a long staining period (e.g., 24 h) is recommended for all stains, as small differences in staining period have the least effect when the root tissue is saturated. To enhance comparability of results in the literature, the staining period, stain, (maximum) root density, scanner resolution and threshold should always be listed when root data obtained by scanning are presented.

As pontes e viadutos mistos de aço e concreto, em especial na configuração em seção caixão, possuem diversas vantagens estruturais e construtivas. Todavia, há uma grande discrepância nas recomendações para o cálculo da largura efetiva da laje. Por esse motivo, estuda-se a influência de tal variação no projeto de pontes e viadutos mistos de aço e concreto em seção caixão. Para tanto, foram dimensionados 11 modelos, variando a seção transversal e o vão, nos quais, considerando as recomendações das normas NBR 8800 (2008), AASHTO (2017), EN 1994-2-2 (2005) e as da literatura de Zhu et al. (2015) e Yuan et al. (2016), calculou-se a capacidade resistente ao momento fletor da seção mista e o carregamento distribuído limite para o dimensionamento no Estado Limite de Serviço. Nas análises, comparando os valores de capacidade resistente ao momento fletor médio da NBR 8800 (2008) com a AASHTO (2017), a primeira apresenta valores 17,07% superiores. Além disso, a NBR 8800 (2008) e o EN 1994-2-2 (2005) permitem carregamentos distribuídos limites superiores, em média, 14,51% e 13,18%, respectivamente, às possibilitadas pela AASHTO (2017). Além disso, quanto maior o vão das pontes e viadutos, maior é a variação global na resistência da seção mista. Portanto, a discrepância entre as recomendações normativas exerce influência de forma significativa no processo de dimensionamento, sendo importante a realização de estudos nessa área a fim de uniformizar os procedimentos para determinar a largura efetiva.

Recolonization of Europe by forest tree species after the last glaciation is well documented in the fossil pollen record. This spread may have been achieved at low densities by rare events of long-distance dispersal, rather than by a compact wave of advance, generating a patchy genetic structure through founder effects. In long-lived oak species this structure could still be discernible by using maternally transmitted genetic markers. To test this hypothesis, a fine-scale study of chloroplast DNA (cpDNA) variability of two sympatric oak species was carried out in western France. The distributions of six cpDNA length variants were analyzed at 188 localities over a 200 X 300 km area. A cpDNA map was obtained by applying geostatistics methods to the complete data set. Patches of several hundred square kilometers exist which are virtually fixed for a single haplotype for both oak species. This local systematic interspecific sharing of the maternal genome strongly suggests that long-distance seed dispersal events followed by interspecific exchanges were involved at the time of colonization, about 10,000 years ago

The nematicidal activity of four molecular weights (2.27 x 10**5, 3.60 x 10**5, 5.97 x 10**5, and 9.47 x 10**5 g/mol) of a biopolymer chitosan was assayed against the root-knot nematode, Meloidogyne incognita, in vitro and in pot experiments. In laboratory assays, the nematode mortality was significantly influenced by exposure times and chitosan molecular weight. Low molecular weight chitosan (2.27 x 10**5 g/mol) was the most effective in killing the nematode with EC50 of 283.47 and 124.90 mg/L after 24 and 48 h of treatment, respectively. In a greenhouse bioassay, all the compounds mixed in soil at one- and five-fold concentrations of the LC50 value significantly reduced population, egg mass, and root galling of tomato seedlings compared with the untreated control. In general, the nematicidal activity of these compounds was increased dramatically with a decrease in the molecular weight. The results suggest that the chitosan at low molecular weight may serve as a natural nematicide.

The effects of plant hormones and sucrose (Suc) on potato (Solanum tuberosum L.) tuberization were studied using in vitro cultured single-node cuttings. Tuber-inducing (high Suc) and-noninducing (low Suc or high Suc plus gibberellin [GA]) media were tested. Tuberization frequencies, tuber widths, and stolon lengths were measured during successive stages of development. Endogenous GAs and abscisic acid (ABA) were identified and quantified by high-performance liquid chromatography and gas chromatography-mass spectrometry. Exogenous GA4/7 promoted stolon elongation and inhibited tuber formation, whereas exogenous ABA stimulated tuberization and reduced stolon length. Indoleacetic acid-containing media severely inhibited elongation of stolons and smaller sessile tubers were formed. Exogenous cytokinins did not affect stolon elongation and tuber formation. Endogenous GA1 level was high during stolon elongation and decreased when stolon tips started to swell under inducing conditions, whereas it remained high under noninducing conditions. GA1 levels were negatively correlated with Suc concentration in the medium. We conclude that GA1 is likely to be the active GA during tuber formation. Endogenous ABA levels decreased during stolon and tuber development, and ABA levels were similar under inducing and noninducing conditions. Our results indicate that GA is a dominant regulator in tuber formation: ABA stimulates tuberization by counteracting GA, and Suc regulates tuber formation by influencing GA levels