2,212 research outputs found

    A Mixed Data-Based Deep Neural Network to Estimate Leaf Area Index in Wheat Breeding Trials

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    Remote and non-destructive estimation of leaf area index (LAI) has been a challenge in the last few decades as the direct and indirect methods available are laborious and time-consuming. The recent emergence of high-throughput plant phenotyping platforms has increased the need to develop new phenotyping tools for better decision-making by breeders. In this paper, a novel model based on artificial intelligence algorithms and nadir-view red green blue (RGB) images taken from a terrestrial high throughput phenotyping platform is presented. The model mixes numerical data collected in a wheat breeding field and visual features extracted from the images to make rapid and accurate LAI estimations. Model-based LAI estimations were validated against LAI measurements determined non-destructively using an allometric relationship obtained in this study. The model performance was also compared with LAI estimates obtained by other classical indirect methods based on bottom-up hemispherical images and gaps fraction theory. Model-based LAI estimations were highly correlated with ground-truth LAI. The model performance was slightly better than that of the hemispherical image-based method, which tended to underestimate LAI. These results show the great potential of the developed model for near real-time LAI estimation, which can be further improved in the future by increasing the dataset used to train the model

    Forest disturbance and recovery: A general review in the context of spaceborne remote sensing of impacts on aboveground biomass and canopy structure

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    Abrupt forest disturbances generating gaps \u3e0.001 km2 impact roughly 0.4–0.7 million km2a−1. Fire, windstorms, logging, and shifting cultivation are dominant disturbances; minor contributors are land conversion, flooding, landslides, and avalanches. All can have substantial impacts on canopy biomass and structure. Quantifying disturbance location, extent, severity, and the fate of disturbed biomass will improve carbon budget estimates and lead to better initialization, parameterization, and/or testing of forest carbon cycle models. Spaceborne remote sensing maps large-scale forest disturbance occurrence, location, and extent, particularly with moderate- and fine-scale resolution passive optical/near-infrared (NIR) instruments. High-resolution remote sensing (e.g., ∼1 m passive optical/NIR, or small footprint lidar) can map crown geometry and gaps, but has rarely been systematically applied to study small-scale disturbance and natural mortality gap dynamics over large regions. Reducing uncertainty in disturbance and recovery impacts on global forest carbon balance requires quantification of (1) predisturbance forest biomass; (2) disturbance impact on standing biomass and its fate; and (3) rate of biomass accumulation during recovery. Active remote sensing data (e.g., lidar, radar) are more directly indicative of canopy biomass and many structural properties than passive instrument data; a new generation of instruments designed to generate global coverage/sampling of canopy biomass and structure can improve our ability to quantify the carbon balance of Earth\u27s forests. Generating a high-quality quantitative assessment of disturbance impacts on canopy biomass and structure with spaceborne remote sensing requires comprehensive, well designed, and well coordinated field programs collecting high-quality ground-based data and linkages to dynamical models that can use this information

    Host Responses in Life-History Traits and Tolerance to Virus Infection in Arabidopsis thaliana

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    Knowing how hosts respond to parasite infection is paramount in understanding the effects of parasites on host populations and hence host–parasite co-evolution. Modification of life-history traits in response to parasitism has received less attention than other defence strategies. Life-history theory predicts that parasitised hosts will increase reproductive effort and accelerate reproduction. However, empirical analyses of these predictions are few and mostly limited to animal-parasite systems. We have analysed life-history trait responses in 18 accessions of Arabidopsis thaliana infected at two different developmental stages with three strains of Cucumber mosaic virus (CMV). Accessions were divided into two groups according to allometric relationships; these groups differed also in their tolerance to CMV infection. Life-history trait modification upon virus infection depended on the host genotype and the stage at infection. While all accessions delayed flowering, only the more tolerant allometric group modified resource allocation to increase the production of reproductive structures and progeny, and reduced the length of reproductive period. Our results are in agreement with modifications of life-history traits reported for parasitised animals and with predictions from life-history theory. Thus, we provide empirical support for the general validity of theoretical predictions. In addition, this experimental approach allowed us to quantitatively estimate the genetic determinism of life-history trait plasticity and to evaluate the role of life-history trait modification in defence against parasites, two largely unexplored issues

    Host responses in life-history traits and tolerance to virus infection in Arabidopsis thaliana

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    Knowing how hosts respond to parasite infection is paramount in understanding the effects of parasites on host populations and hence host¿parasite co-evolution. Modification of life-history traits in response to parasitism has received less attention than other defence strategies. Life-history theory predicts that parasitised hosts will increase reproductive effort and accelerate reproduction. However, empirical analyses of these predictions are few and mostly limited to animalparasite systems. We have analysed life-history trait responses in 18 accessions of Arabidopsis thaliana infected at two different developmental stages with three strains of Cucumber mosaic virus (CMV). Accessions were divided into two groups according to allometric relationships; these groups differed also in their tolerance to CMV infection. Life-history trait modification upon virus infection depended on the host genotype and the stage at infection. While all accessions delayed flowering, only the more tolerant allometric group modified resource allocation to increase the production of reproductive structures and progeny, and reduced the length of reproductive period. Our results are in agreement with modifications of life-history traits reported for parasitised animals and with predictions from life-history theory. Thus, we provide empirical support for the general validity of theoretical predictions. In addition, this experimental approach allowed us to quantitatively estimate the genetic determinism of life-history trait plasticity and to evaluate the role of life-history trait modification in defence against parasites, two largely unexplored issues

    A Conceptual Framework for Mapping Quantitative Trait Loci Regulating Ontogenetic Allometry

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    Although ontogenetic changes in body shape and its associated allometry has been studied for over a century, essentially nothing is known about their underlying genetic and developmental mechanisms. One of the reasons for this ignorance is the unavailability of a conceptual framework to formulate the experimental design for data collection and statistical models for data analyses. We developed a framework model for unraveling the genetic machinery for ontogenetic changes of allometry. The model incorporates the mathematical aspects of ontogenetic growth and allometry into a maximum likelihood framework for quantitative trait locus (QTL) mapping. As a quantitative platform, the model allows for the testing of a number of biologically meaningful hypotheses to explore the pleiotropic basis of the QTL that regulate ontogeny and allometry. Simulation studies and real data analysis of a live example in soybean have been performed to investigate the statistical behavior of the model and validate its practical utilization. The statistical model proposed will help to study the genetic architecture of complex phenotypes and, therefore, gain better insights into the mechanistic regulation for developmental patterns and processes in organisms

    STUDY OF MORPHOLOGICAL AND PHYSIOLOGICAL PROPERTIES AND POLLINATORS OF THE INVASIVE CALLERY PEAR

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    Callery pear is an invasive tree in 15 states of United States and is currently present in 37 states. Its management has challenged landowners and land managers. Despite being listed as a noxious weed in four states, its study is limited. The accurate estimation of Callery pear biomass will give a clearer picture of the level of invasion and help land managers develop different strategies to control its population. Similarly, identifying possible pollinators of Callery pear is essential to have some insights on pollinators associated with this tree. Hence, the objectives of this study are 1) to calculate total above-ground biomass and prepare allometric equation, and 2) identify the pollinator taxa and calculate diversity metrics and community composition of pollinators using Callery pear. Forty trees from six different sites were destructively harvested. We measured diameter at breast height (DBH), total tree height, fresh weight, oven-dry weight, C:N ratio and moisture content of different tree components (i.e., leaves, fruits, stem, and branches) and examine their relationship with each other. Biomass of each tissue component was significantly related to DBH. Total wet biomass ranged from 326.75 g (1.27 cm DBH) to 160 kg (17.52 cm DBH), and total dry biomass ranged from 193.25 g to 97 kg for the same DBH. The average moisture content ranged from 39% to 42 % and the average wood density was found to be 0.88 gm/cm3. The model/equation determined for the biomass is Log linear model with 91% variation explained by the model. Five sites in South Carolina were surveyed using yellow, blue, white colored plastic cups and sweep net methods. A total of 756 insects were collected, belonging to 15 families in three orders; Diptera (611), Hymenoptera (135), and Coleoptera (10). The most common families of insects visiting Callery pear were Syrphidae, Sarcophagidae, Anthomyiidae, and Andrenidae with common species being Toxomerus, Andrena, Apis mellifera, Osmia, and Lasioglossum. Because of being present in highest number in all sites, we propose that Toxomerus spp. from Syrphidae family are the major visitors of Callery pear’s flower whereas sweep net and yellow bowl trap are most suitable methods of collecting them

    Growth and Genetic Analysis of Pejibaye (Bactris Gasipaes Kunth, Palmae)in Hawai'i

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    Pejibaye or peach palm {Bactris gasipaes, Kunth) was introduced into Hawai’i to supply the gourmet market with fresh heart of palm. New crop introduction requires evaluation of crop adaptation to its new environment and planning for future development, including genetic improvement. Leaf number of open-pollinated Benjamin Constant (Putumayo landrace) progenies was lower at harvest (6-8) than elsewhere (8- 10), and offshoot number dropped dramatically from first harvest (6.5) to second harvest (2). Allometric equations for estimating whole plant leaf area and biomass were developed, using height and leaf number predictors. No significant plant population (density) effects on individual plant dimensions or growth were found over the range of 3333 to 6666 plants/ha. Relative growth rate (RGR) and unit leaf rate (E ^ between nursery and first harvest were highly correlated (r = -0.99 and -0.95, respectively) with earliness (days to harvest). The early progenies partitioned photoassimilates differently; two had high E^, while one had moderate E^ and partitioned preferentially to leaf area, resulting in a higher leaf area ratio. Heart of palm yields were close to 900 kg/ha after 12 months of harvest and 1400 kg/ha after 18 months, both comparable to tropical American yields. When edible stem and leaf were added to the yields, these increased to 2.8 and 4.5 t/ha of marketable product, respectively. Quantitative genetic analysis of growth parameters suggested high levels of inbreeding in the germplasm studied, since the narrow-sense heritabilities were double those observed in other perennials. Additive genetic variances for RGR and earliness suggested the potential for significant response to selection, but phenotypic variation varied depending on the interval over which RGR was estimated. The lowest estimate of RGR (over an entire development phase) provided the smallest response to selection but is similar to the response observed in other crops. Allozyme heterozygosity was remarkably low, ranging from 0.038 to 0.099, with a mean of 0.074, on par with inbred crops, rather than outbreeders. There was a lack of correlation between allozyme heterozygosity and growth parameters and morphological traits

    Growth, seed development and genetic analysis in wild type and Def mutant of Pisum sativum L

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    <p>Abstract</p> <p>Background</p> <p>The <it>def </it>mutant pea (<it>Pisum sativum </it>L) showed non-abscission of seeds from the funicule. Here we present data on seed development and growth pattern and their relationship in predicting this particular trait in wild type and mutant lines as well as the inheritance pattern of the <it>def </it>allele in F<sub>2 </sub>and F<sub>3 </sub>populations.</p> <p>Findings</p> <p>Pod length and seed fresh weight increase with fruit maturity and this may affect the abscission event in pea seeds. However, the seed position in either the distal and proximal ends of the pod did not show any difference. The growth factors of seed fresh weight (FW), width of funicles (WFN), seed width (SW) and seed height (SH) were highly correlated and their relationships were determined in both wild type and <it>def </it>mutant peas. The coefficient of determination <it>R</it><sup>2 </sup>values for the relationship between WFN and FW, SW and SH and their various interactions were higher for the <it>def </it>dwarf type. Stepwise multiple regression analysis showed that variation of WFN was associated with SH and SW. Pearson's chi square analysis revealed that the inheritance and segregation of the <it>Def </it>locus in 3:1 ratio was significant in two F<sub>2 </sub>populations. Structural analysis of the F3 population was used to confirm the inheritance status of the <it>Def </it>locus in F<sub>2 </sub>heterozygote plants.</p> <p>Conclusions</p> <p>This study investigated the inheritance of the presence or absence of the <it>Def </it>allele, controlling the presence of an abscission zone (AZ) or an abscission-less zone (ALZ) forming in wild type and mutant lines respectively. The single major gene (<it>Def</it>) controlling this phenotype was monogenic and <it>def </it>mutants were characterized and controlled by the homozygous recessive <it>def </it>allele that showed no palisade layers in the hilum region of the seed coat.</p
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