Total Aerial Biomass Research Articles

Selection for domestication favored taxa characterized by fast growth and tolerance of high intraspecific density

Societal Impact StatementTo understand why certain plants have been domesticated into crops, we need to recognize that the environmental conditions plants experience in wild populations are totally different from those of agricultural fields. In this study, we investigated whether the characteristics that promote growth and survival in these different environments may have influenced domestication. Our results revealed that ancestral crops were selected because they developed better than other plants in dense single‐species stands, with selection for increased yield likely occurring after domestication. These insights shed light on the origins of agriculture and offer valuable guidance for future crop breeding efforts.Summary In spite of a large history of research, it is still unclear which functional traits may have mediated plant domestication. Solving this problem requires consideration of the ecological and demographic disparities between natural plant populations and cultivated fields. Since population density tends to be higher in the latter, we hypothesized that traits facilitating growth and survival in dense, monospecific populations might have been relevant for initial domestication. We investigated whether functional traits that respond to population density varied across three different domestication stages: undomesticated crop wild relatives, natural populations of crop progenitors, and landraces. To do this, we compared traits influencing competition (lodging; growth rate), resource acquisition (plant height; total aerial and root biomass) and yield (fruit number) in three annual legume crops—lentil, grasspea, and vetch—grown without resource limitation at three different densities. Our results showed clear differences among species, likely reflective of the distinct uses of the crops and their domestication pathways. Nevertheless, undomesticated relatives consistently differed from crop progenitors and landraces, producing smaller, slower‐growing plants that were more prostrate and allocated less biomass to roots. The effect of selection under domestication on these vegetative traits appeared to be largely negligible. Conversely, landraces produced more fruits. We conclude that early agriculturalists selected for domestication wild legumes that performed well in dense monocultures and were more effective in resource capture. Later domestication and breeding efforts likely had more significant effects on reproductive traits, such as fruit and seed production.

Carbon stock estimation in halophytic wooded savannas of Uruguay: An ecosystem approach

Savannas constitute a mixture of trees and shrub patches with a more continuous herbaceous understory. The contribution of this biome to the soil organic carbon (SOC) and above-ground biomass (AGB) carbon (C) stock globally is significant. However, they are frequently subjected to land use changes, promoting increases in CO2 emissions. In Uruguay, subtropical wooded savannas cover around 100,000 ​ha, of which approximately 28% is circumscribed to sodic soils (i.e., subtropical halophytic wooded savannas). Nevertheless, there is little background about the contribution of each ecosystem component to the C stock as well as site-specific allometric equations. The study was conducted in 5 ​ha of subtropical halophytic wooded savannas of the national protected area Esteros y Algarrobales del Río Uruguay. This work aimed to estimate the contribution of the main ecosystem components (e.g., soil, trees, shrubs, and herbaceous plants) to the C stock. Site-specific allometric equations for the most frequent tree species and shrub genus were fitted based on basal diameter (BD) and total height (H). The fitted equations accounted for between 77% and 98% of the aerial biomass variance of Neltuma affinis and Vachellia caven. For shrubs (Baccharis sp.), the adjusted equation accounted for 86% of total aerial biomass. C stock for the entire system was 116.71 ​± ​11.07 ​Mg⋅ha−1, of which 90.7% was allocated in the soil, 8.3% in the trees, 0.8% in the herbaceous plants, and 0.2% in the shrubs. These results highlight the importance of subtropical halophytic wooded savannas as C sinks and their relevance in the mitigation of global warming under a climate change scenario.

Effects of agricultural management and of climate change on N2O emissions in an area of the Brazilian Cerrado: Measurements and simulations using the STICS soil-crop model

Soil-plant simulation models have been ever more used as predictive tools to evaluate productivity and environmental impacts of agriculture practices. The aims of this work were to evaluate the STICS model’s capacity of simulate the emissions of nitrous oxide (N2O) under different management systems. And, to predict, by applying the calibrated and validated STICS model, the N2O emissions, under different management systems, in the edaphoclimatic conditions of the Brazilian Cerrado. The study was conducted in a long-term experiment at Embrapa Cerrados, located in Planaltina/DF, Brazil. The experiment started in 1995. The following land use systems were evaluated: CT - conventional tillage with disc harrow, and biannual grass/legume rotation; NT1 - No-tillage, with biannual crop rotation – soybean/sorghum; NT2 - No-tillage, with biannual crop rotation – maize/pigeon pea.Closed static chambers and gas sample analysis by gas chromatography were used to measure N2O fluxes. The model was calibrated with the data measured in the CT and NT1 treatments. The attributes used in the calibration were: growth, development and yield of crops and N2O fluxes. To test the model, data from the NT2 treatment was used. Data for all treatments were collected at the same time. After calibration and validation, the STICS model was used to predict the effects of soil management systems, conventional (CT) and no-tillage (NT) on greenhouse gas emissions and on grain and biomass crops production. The simulation was made for the period from 2021 to 2070. The STICS model performed well at simulation of the following parameters: N2O emissions, soil water dynamics, soil temperature; and leaf area, aerial biomass and grain yield of soybean and maize. The performance of the model was good for the conventional soil management system as well as in the no-tillage system. Based on the predicted increase in temperature for the period 2021–2070, we can conclude from the data generated through the STICS model that there is strong evidence that grain yield and total aerial biomass of plants will decrease. The data show that there is a rising tendency in N2O emissions over the simulated period. This is expected to occur for the two soil management systems studied (NT and CT). We believe this increase in emissions along the years is related to temperature increase and to the reduction of crop cycle.

Impact of polyethylene microplastics and copper nanoparticles: Responses of soil microbiological properties and strawberry growth

Microplastics (MPs) can act as vectors of contaminants such as fungicides and trace metals. Their presence in water or soil might affect fruits and vegetables, while interactions between MPs and copper (Cu) nanoparticles might pose greater risks to soil properties, plant development and yield. The objective of this study was to evaluate the effect of the presence of MPs and Cu nanoparticles on plant growth and yield of strawberry, as well as on soil microbiological properties. The experiment was carried out in pots in a greenhouse; the soil was contaminated with polyethylene MPs and Cu nanoparticles. The design was completely randomized with four treatments (control, MPs, Cu, and Cu + MPs). Six months after planting, significant changes were observed in terms of plant height, stem diameter and root surface area. When compared to the control treatment, the MPs treatment resulted in a 27 % decrease in plant height, lower stem diameter values in all the contaminant treatments, and decreases in root surface area by 20 %, 21 % and 17 % in the MPs, Cu, and Cu + MPs treatments, respectively. Regarding number of inflorescences, total number of fruits, fruit weight and total aerial biomass, the MPs, Cu, and Cu + MPs treatments were statistically lower than the control (p < 0.05). The soil dehydrogenase activity decreased by 30 % due to the combined application of MPs and Cu nanoparticles, but this was not observed when MPs or Cu nanoparticles were applied alone, evidencing possible effects on the biological activity of the soil. Significant differences were found in acid phosphatase and urease activities in the Cu treatments with respect to the control and MPs treatments except for soil respiration. It can be concluded that the presence of Cu nanoparticles combined with polyethylene MPs favored a greater Cu availability in the soil and root Cu accumulation of strawberry plants.

Influence of Ipomoea muricata (L)Jacq. Weed Manure on The Aerial Biomass of Maize Crop

In India agriculture was traditionally organic till the 1950. The green revolution was ushered in country during sixty and transformed the stage of food deficiency to self-sufficiency. Fertilizers no doubt increased the quantity of yield and reduced diseases but continuous use of chemical fertilizers causes several side effects on soil. Soil becomes hard and impervious to water. Maintenance of soil fertility is now prerequisite. Organic farming is the solution. There are several organic components which are the good source of organic manure. Weed biomass available abundantly. Weeds are considered as unwanted plants and are competitors to the crop plants. There are several methods to control the weed. The best way to control weed is to make use of it. Ipomoea muricata (L). Jacq. is large herbaceous twiner commonly called as Bhowari in Marathi. It is common weed grow luxuriously on waste land. Present investigation deals with utilization of Ipomoea muricata weed as a source of organic manure and its influence on the aerial biomass of maize. various types of Ipomoea muricata weed manures like Compost, Dry Leaf manure, Green Leaf manure, Mixed manure (equal amount of Ipomoea muricata +Euphorbia prunifolia+Trianthema portulacastrum) are prepared and compared with NPK and Control treatment to maize crop field. Crop was harvested after 87 days of sowing. Samples from each treated plots collected and analysed as total aerial biomass, Dry weight, Reducing Sugar, Nitrogen, Crude protein and nitrogen efficiency ratio. All the nutrient contents show high amounts in weed manure amended samples of Maize as compared to NPK and control treatment.

Expressing the sunflower transcription factor HaHB11 in maize improves waterlogging and defoliation tolerance.

The sunflower (Helianthus annuus) transcription factor HaHB11 (H. annuus Homeobox 11) belongs to the homeodomain-leucine zipper family and confers improved yield to maize (Zea mays) hybrids (HiII × B73) and lines. Here we report that transgenic maize lines expressing HaHB11 exhibited better performance under waterlogging, both in greenhouse and field trials carried out during three growth cycles. Transgenic plants had increased chlorophyll content, wider stems, more nodal roots, greater total aerial biomass, a higher harvest index, and increased plant grain yield. Under severe defoliation caused by a windstorm during flowering, transgenic genotypes were able to set more grains than controls. This response was confirmed in controlled defoliation assays. Hybrids generated by crossing B73 HaHB11 lines with the contrasting Mo17 lines were also tested in the field and exhibited the same beneficial traits as the parental lines, compared with their respective controls. Moreover, they were less penalized by stress than commercial hybrids. Waterlogging tolerance increased via improvement of the root system, including more xylem vessels, reduced tissue damage, less superoxide accumulation, and altered carbohydrate metabolism. Multivariate analyses corroborated the robustness of the differential traits observed. Furthermore, canopy spectral reflectance data, computing 29 vegetation indices associated with biomass, chlorophyll, and abiotic stress, helped to distinguish genotypes as well as their growing conditions. Altogether the results reported here indicate that this sunflower gene constitutes a suitable tool to improve maize plants for environments prone to waterlogging and/or wind defoliation.

Productivity, adaptability, and stability in Guazuma crinita progeny tests across three environments in the Aguaytia River Basin, Ucayali, Perú

Abstract Guazuma crinita is a fast-growing tree with potential for use in agroforestry systems, due to its rapid wood production, which can contribute significantly to the livelihoods of small-scale farmers in the Peruvian Amazon. However, indiscriminate logging due to high demand is leading to the disappearance of natural forests. As such, the International Council for Research in Agroforestry (ICRAF) began a domestication program to reduce pressure on natural populations of the species. The objective of the present study was to use analyses of genetic parameters, adaptability (PRVG), productivity (MHPRVG), and stability (MHVG), to select G. crinita genotypes from a three-year-old progeny test established in the Aguaytía River Basin, in Ucayali, Peru. The test was established in three different sites, with three blocks, 200 progeny per block, and two individuals per plot. The measured traits were diameter at breast height (DBH), total height (H), and total aerial biomass (B). Significant differences in traits between progenies were detected, but with no genotype x environment interaction (GxE). However, the genotypic correlation among sites was important (&gt; 0.702), suggesting that genetic improvement is possible by selecting the same progeny across sites. The mean heritability among progenies was moderate for all traits (0.34–0.369) and selective precision through combined site analysis was relatively high (0.583–0.608). Based on selection for DBH through combined analysis, MHVG, PRVG, and MHPRVG, 50 superior progenies (25.9 %) were identified for all environments. These should be prioritized in breeding programs as they can offer stable genetic variability for future selection cycles.

FARM DAIRY EFFLUENT APPLICATION ON AN ARGIUDOLL CULTIVATED WITH ALFALFA (Medicago sativa L.): BIOMASS PRODUCTION AND PERSISTENCE

The intensification of dairy production systems has resulted in a higher generation of waste. The aim of this study was to evaluate the impact of different doses of farm dairy effluent (FDE) applied to the soil on aerial biomass production, persistence and chemical composition of alfalfa pastures, in Santa Fe province, Argentina. The study was conducted in four randomized complete blocks with four treatments (FDE doses): 0 m3 ha-1 (T0: without FDE), 82 m3 ha-1 (T1: low rate), 151 m3 ha-1 (T2: medium rate) and 282 m3 ha-1 (T3: high rate). The soil application of FDE increased the total aerial biomass produced (ABP) but reduced the persistence of plants. Total nitrogen (Nt) of alfalfa was significantly higher, but phosphorus (P) concentrations did not vary after the application of FDE to the soil . Ca and Mg concentrations in plants were lower in T3 compared to T0, which can be explained by the imbalance produced in the soil after FDE was applied, presenting high levels of Na, K and NH4-N but low levels of Ca and Mg. Soil application of FDE on alfalfa pastures must be carefully planned in terms of composition and amount to be applied in order to increase biomass production, prevent the decrease in persistence, and control changes in the mineral composition of plants.

Estudio técnico-económico para identificar áreas con potencial para producir piña en el trópico húmedo de México

Con el objetivo de identificar el potencial productivo y económico del cultivo de piña a nivel de unidad de respuesta hidrológica, cuenca y estado, considerando el rendimiento y la relación beneficio costo (R B/C), se realizó un estudio técnico-económico, en los principales estados productores del Trópico Húmedo de México. Para ello se simuló y cartografió el rendimiento potencial de biomasa aérea total y fruta de piña en nueve estados del sur-sureste de México y se identificaron las áreas con mayor potencial para el cultivo. Asimismo, se estimaron los costos de establecimiento, de mantenimiento e ingresos del paquete tecnológico de malla sombra y se evaluó la rentabilidad financiera del cultivo para cada región identificada. Los resultados muestran que el cultivo de piña es rentable cuando se produce más de 45.8 t ha-1. Se identificaron 596 666 ha con potencial para producir piña, ubicadas en Campeche, Chiapas, Oaxaca, Puebla, Quintana Roo, Tabasco, Veracruz y Yucatán, siendo el estado de Campeche el que presentó el mayor rendimiento (90 t ha-1) y una R B/C de 1.88. Se concluye que la producción de piña es rentable en aquellas regiones que presentan condiciones agroecológicas idóneas para su producción.

Influence of water deficit and defoliation managements on post‐drought recovery and persistence of smooth bromegrass

AbstractIn arid and semiarid regions, successful recovery from drought may be of more economic significance than plant productivity during a dry season. This research was conducted to investigate the effects of pre‐drought irrigation and defoliation managements (seed and forage managements) on post‐drought recovery of diverse smooth bromegrass (Bromus inermis Leyss.) genotypes, and to identify growth traits associated with persistence and recovery as indices for selecting superior genotypes. Thirty‐six genotypes were field evaluated in two separate experiments of seed and forage managements during 2013–2015 under well‐watered and deficit irrigation regimes. In the fourth year (2016), irrigation was withheld from both moisture regimes for two months (almost complete senescence) and then plants were re‐watered to find the effect of prolonged drought stress on post‐drought recovery. Pre‐drought irrigation increased persistence of genotypes relative to the well‐watered treatment in the seed management experiment. In the seed management trial, genotypes had greater recovery under deficit irrigation when compared to forage management counterpart. There was no significant difference between seed and forage management experiments under the well‐watered regime in this respect. Positive correlations were observed between recovery after prolonged drought and total aerial biomass, persistence, and winter growth vigor under both irrigation regimes. Superior genotypes were identified as having more productivity, better recovery, higher persistence, and drought tolerance.

Species – Specific Allometric Equations for Predicting Biomass of Faidherbia albida (Del.) A. Chev. In the Sudano-sahelian Savannahs of Far-North, Cameroon

To contribute to the accurate assessment of carbon of agroforest species of Sudano-sahelian ecosystems, a study based on the establishment of mono-specific allometric equations were investigated in the arboreous parks of the Far-North Cameroon. A total of 20 individual trees of Faidherbia albida was harvested in savannah and distributed across a range of diameter classes, from 10 to 60 cm. The diameter at breast height of these individuals and their height were measured. After tree cutting, biomass of compartments of leave, branches and stem were determined after drying and weighing. Various allometric equations between biomasses and two parameters of the tree (the diameter and the height) were tested. The adjusted coefficient of determination (R2adj), the residual standard error (RSE) and the Akaike Information Criteria were used for choosing the best models. The main results reveal that there is a positive and significant relationship between the height of the trees and their diameter (R2 = 0.75, n = 17 and P &lt; 0.05). The best model for the biomass prediction of all compartments of F. albida is in the form ln(B) = a + b*ln(D2H), with ln(B) = -1.42 + 0.58*ln(D2H) for leaf biomass, ln(B) = - 5.83 + 1.11*ln(D2H) for the branch, ln(B) = - 4.01 + 0.94*ln(D2H) for the stem, and finally ln(B) = -2.83 + 0.91*ln(D2H) for the total biomass. Their adjusted coefficient of determination is 0.71, 0.90, 0.93 and 0.93 respectively. The branch biomass represents about 42.16% of the total aerial biomass and is the highest relative to the other compartments. Theses equations bring a contribution to a reliable and quick assessment of carbon stock of arboreous parks to F. albida in the framework of study on climate change mitigation in Sudano-sahelian zone in particular and in the World in general.

Consumption, digestibility and cattle condition according to forage composition and quality in maize-cattle from conservation-based agroecosystems

The cereal-cattle conservation-based agroecosystems in neotropical savannas are based on the introduction of a forage of better quality than that of the native pasture. This forage acts as a soil protective coverage under non-tillage managements and like green manure to the maize culture. In order to evaluate how the consumption by bovine, digestibility and animal condition changes in these agroecosystems, we study, during a grazing cycle (110 days in the dry season), the following: total aerial biomass (TAB), green leaf biomass (GLB), fiber content of the leaves (lignin, ADF and NDF), botanic composition of the cattle excreta by microhistological analysis, N-NH3 content in the cattle rumen and the presence of urea in blood. The introduced species were Brachiaria dyctioneura grass (Bd) and Centrosema macrocarpum legume (Cm), both perennials, associated to maize for 4 years of non-tillage management and alternative phosphorus sources. During the grazing period, the level of N-NH3 in the rumen was 12.1 mg/L and 16.6 mg/L in the animals of the agroecosystems Bd and Cm, respectively. In the case of urea in blood, the concentration was significantly higher under legume (24.6 mg/dL) compared to the grass (9.7 mg/dL). Daily weight gain favored Bd (0.68 kg/d) > Cm (0.29 kg/d) > NS (−0.006 kg/d). Body condition was significantly higher in introduced pastures compared to NS. At this time, the microhistological studies of the cattle excreta showed a significant variation of the Bd and Cm consumption, selecting as second option Andropogon gayanus and maize (Zea mays) residues in a higher percentage, depending of the dominant cover crop. Thus, the digestibility was related to the appearance frequency of these species (p < 0.01). The GLB of Cm decreased significantly during the grazing. At the same time, the lignin content increased in both cover crops, influencing the consumption, digestibility and daily weight gain (DWG) of the cattle in the agroecosystems, compared to savanna ecosystem.

Woody biomass accumulation in a Cerrado of Central Brazil monitored for 27 years after the implementation of silvicultural systems

The Brazilian Cerrado is the second largest biome in Brazil, and its natural landscapes have undergone transformations, due in large part to anthropic activities. However, little is known about the effects of these activities on the natural regeneration of Cerrado vegetation. Thus, the objective of this study was to evaluate the accumulation of woody biomass in an area of a Cerrado sensu stricto that was monitored for 27 years after the implementation of six silvicultural systems.A period of 17 years was sufficient for the woody community of the Cerrado sensu stricto to naturally recover its original stock of aerial biomass after the application of silvicultural systems. A Few woody species contribute to the total aerial biomass accumulated over time, and such contribution is variable with time and with the type of silvicultural system.At 27 years after cutting, the largest fraction of biomass accumulated in the area were represented by the species Miconia leucocarpa, Blepharocalyx salicifolius, Schefflera macrocarpa, Qualea grandiflora, Dalbergia miscolobium, Eriotheca pubescens, Qualea parviflora and Caryocar Brasiliense, which also demonstrated higher fire resistance.A period of 17 years after the implementation of silvicultural systems is considered sufficient for an area to recover naturally to the original stock of woody biomass at the community level. This result causes a greater reduction in the biomass of fire-sensitive species and transforms a Cerrado from a carbon sink into a source of CO2 emissions to the atmosphere.

Aerial biomass allometric models for Prosopis affinis Spreng. in native Espinal forests of Argentina

ABSTRACT Estimation of carbon stored in forest ecosystems requires accurate biomass prediction tools. The objective of this study was to determine the individual aerial biomass of Prosopis affinis and its distribution by component, to develop allometric models for the estimation of biomass and to estimate biomass expansion factors (BEF) in native forests of Entre Ríos (Argentina). Dendrometric variables on 30 individuals of different diameter classes were measured. Values of total aerial biomass and component biomass (trunk, branches larger than 5 cm in diameter and branches smaller than 5 cm + leaves, flowers and fruits) were determined using the destructive method. Different models were developed, and the best models were selected according to the adjusted coefficient of determination (R2adj), mean squared prediction error, the Akaike information and Bayesian information criteria and the Furnival index. The variables crown area, diameter at breast height and total height were the best estimators of total aerial biomass and component biomass of P. affinis. The single-variable model based on the basal diameter has a very good predictive capacity for total aerial biomass, resulting in a simple model of great practicality. The BEF was significantly different among diameter classes, with mean values between 2.28 and 4.90. The highest values corresponded to individuals with trunk diameters larger than 25 cm. The models developed in this work present high precision (R2adj. ≥ 0.94) for the prediction of total aerial biomass of P. affinis and can be applied in the native forest area of the province of Entre Ríos (Argentina).

Factores de expansión y sistema de partición de biomasa aérea para Pinus chiapensis (Martínez) Andresen

En el presente estudio se desarrollaron factores de expansión para biomasa constante y variable, además de un sistema de partición de biomasa aérea en plantaciones forestales comerciales de Pinus chiapensis. Mediante un muestreo destructivo de 35 árboles, se obtuvo el peso fresco de fuste, ramas y follaje en el campo y se tomaron muestras para determinar su peso seco. La relación del peso seco y fresco se empleó para convertir el peso freso en biomasa. A partir de una proporción directa del volumen total del fuste multiplicada por un factor de expansión de biomasa constante se estimó la biomasa aérea. El factor de expansión de biomasa variable se determinó con base en el cociente del modelo de biomasa aérea total y del volumen total del fuste. El sistema de partición de biomasa aérea se ajustó como una función directa de la biomasa y un factor de partición, que define la proporción de la biomasa por componentes. El valor del factor de expansión de biomasa constante reveló que por cada metro cúbico existen 709 kg de biomasa. El sistema de partición de biomasa aérea indicó una distribución de biomasa mayor en el fuste con 69 %, de ramas con 21 % y de follaje con 10 %. La aplicación de los factores de expansión de biomasa y sistema de partición de biomasa aérea permiten calcular la biomasa aérea total y por componentes a partir del volumen total del fuste de los árboles medidos en los inventarios forestales.

Biomasa y carbono en Guadua angustifolia Kunth y Bambusa oldhamii Munro en dos comunidades de la sierra Nororiental de Puebla, México

The increase of CO2 in the atmosphere can be reduced by capturing them through the photosynthetic process, with special emphasis on fast growing perennial species such as bamboo. The objective of the present study was to quantitatively evaluate the aerial biomass and estimate the carbon content for the species Guadua angustifolia Kunth and Bambusa oldhamii Munro, in commercial plantations established in communities of the Northeast Sierra of Puebla, Mexico. The estimation of population and aerial biomass for both species is tended by a selection of 10 % of plants in one hectare. The samplings were carried out from June 2016 to September 2017. For the plantation of B. Oldhamii Munro, the number of culms per plant gradually increased towards the most recent generations, from 3.6 stems in the most adult cohort to 4.5 in the youngest. The diameter of the stems and their average height show a gradual increase from the older cohorts to the recent cohorts. The total aerial biomass estimated in the plantation of B. oldhamii Munro was 103 403 48 Mgha-1 distributed in the asses of the four years. The total aerial biomass estimated in the plantation of G. angustifolia Kunth is 47 665 11 Mgha-1

Diseño de seguros ganaderos paramétricos satelitales de tipo catastrófico: implementación operacional en México.

La implementación operacional de esquemas de gestión de riesgos climáticos, principalmente seguros, es una opción para mitigar los efectos del cambio climático y hacer un uso ef iciente de los recursos f inancieros a escala regional y de país. En el presente trabajo se presenta la experiencia operativa en la implementación de seguros en México, misma que se fundamenta en el desarrollo conceptual-teórico de su marco de implementación. El diseño de seguros ganaderos paramétricos satelitales se basa en la relación Bm = kIV, donde Bm es la biomasa aérea total, IV es un índice espectral de la vegetación y k es una constante empírica. Para lograr esta relación, se utiliza una relación lineal entre el índice espectral NDVIcp y la Bm, la cual se transforma en el índice IVCP (en función de 1/NDVIcp). La ventaja de usar el índice transformado 1/NDVIcp es que tiene patrones lineales en el tiempo, los cuales se pueden usar para su parametrización en términos operacionales. Este desarrollo se discute mediante el uso de un enfoque algorítmico que considera la parametrización de curvas de crecimiento de la vegetación, índice 1/NDVIcp, para el sensor AVHRR. Se presenta, también, la experiencia operacional de la implementación en México y se incluyen las campañas de validación. De la experiencia operativa se concluye que, en un ciclo completo, aún cuando el esquema que se desarrolló reduce los riesgos de base que se asocian al uso de periodos cortos del seguro, permanece el problema de ciclos del crecimiento desfasados, lo que constituye una restricción inherente al considerar una fecha inicial y f inal de vigencia del seguro paramétrico. En esta perspectiva se proponen modif icaciones para desarrollos futuros.

Working towards recalcitrance mechanisms: increased xylan and homogalacturonan production by overexpression of GAlactUronosylTransferase12 (GAUT12) causes increased recalcitrance and decreased growth in Populus

BackgroundThe development of fast-growing hardwood trees as a source of lignocellulosic biomass for biofuel and biomaterial production requires a thorough understanding of the plant cell wall structure and function that underlie the inherent recalcitrance properties of woody biomass. Downregulation of GAUT12.1 in Populus deltoides was recently reported to result in improved biomass saccharification, plant growth, and biomass yield. To further understand GAUT12.1 function in biomass recalcitrance and plant growth, here we report the effects of P. trichocarpa GAUT12.1 overexpression in P. deltoides.ResultsIncreasing GAUT12.1 transcript expression by 7–49% in P. deltoides PtGAUT12.1-overexpression (OE) lines resulted in a nearly complete opposite biomass saccharification and plant growth phenotype to that observed previously in PdGAUT12.1-knockdown (KD) lines. This included significantly reduced glucose, xylose, and total sugar release (12–13%), plant height (6–54%), stem diameter (8–40%), and overall total aerial biomass yield (48–61%) in 3-month-old, greenhouse-grown PtGAUT12.1-OE lines compared to controls. Total lignin content was unaffected by the gene overexpression. Importantly, selected PtGAUT12.1-OE lines retained the recalcitrance and growth phenotypes upon growth for 9 months in the greenhouse and 2.8 years in the field. PtGAUT12.1-OE plants had significantly smaller leaves with lower relative water content, and significantly reduced stem wood xylem cell numbers and size. At the cell wall level, xylose and galacturonic acid contents increased markedly in total cell walls as well as in soluble and insoluble cell wall extracts, consistent with increased amounts of xylan and homogalacturonan in the PtGAUT12.1-OE lines. This led to increased cell wall recalcitrance, as manifested by the 9–15% reduced amounts of recovered extractable wall materials and 8–15% greater amounts of final insoluble pellet in the PtGAUT12.1-OE lines compared to controls.ConclusionsThe combined phenotype and chemotype data from P. deltoides PtGAUT12.1-OE and PdGAUT12.1-KD transgenics clearly establish GAUT12.1 as a recalcitrance- and growth-associated gene in poplar. Overall, the data support the hypothesis that GAUT12.1 synthesizes either an HG-containing primer for xylan synthesis or an HG glycan required for proper xylan deposition, anchoring, and/or architecture in the wall, and the possibility of HG and xylan glycans being connected to each other by a base-sensitive covalent linkage.

Management techniques for the control of Melinis minutiflora P. Beauv. (molasses grass): ten years of research on an invasive grass species in the Brazilian Cerrado

ABSTRACT Th e invasion of exotic species is considered to be a major threat to the preservation of biodiversity. In the Parque Nacional de Brasilia (National Park of Brasilia), the invasive Melinis minutifl ora (molasses grass) occupies more than 10 % of the area of the park. Th e present, long-term, study compared two treatments of exposure to molasses grass: 1) fi re and 2) integrated management (fi re + herbicide sprays + manual removal). Th e aerial biomass of molasses grass in the experimental area initially represented ca. 55 % of the total aerial biomass, a percentage that apparently did not infl uence native plant species richness at this site. Fire alone was not suffi cient to control molasses grass, which attained its pre-treatment biomass values after two years. Integrated management reduced, and maintained, biomass to less than 1 % of its original value after ten years, and maintained this level throughout the study, demonstrating that it is a promising strategy for the recovery of areas invaded by molasses grass in the Cerrado. However, because of the recolonization by molasses grass, long-term monitoring eff orts are targeting outbreaks, which would require immediate intervention in order to maintain the native biological diversity of the region.

Enhancing Connectivity Index to Assess the Effects of Land Use Changes in a Mediterranean Catchment

AbstractIn the Mediterranean region, the long history of cultivation is associated with significant changes in the original landscape. Agricultural intensification and subsequent land abandonment and reforestation have significantly affected the hydrological behaviour and connectivity patterns of hydrological systems. Thus, information on the spatial distribution of land use/cover is essential for monitoring the runoff response to interpret catchment hydrology. A medium‐sized catchment of the central part of the Ebro Basin (NE Spain), representative of Mediterranean mountain agroecosystems, was selected to assess the effect of land use/cover changes during the last few decades on the hydrological network of the catchment. To this end, a topography‐based index, the ‘index of connectivity’, was applied to assess the effects of land use changes from 1957 to 2010. The sediment connectivity was estimated by using a geomorphometric approach to simulate how connectivity changes due to the different land covers. To improve this index, we used a combination of C‐factor, rugosity index and the novel application of a total aerial biomass equation over pine‐reforested areas as a weighting factor. A high‐resolution (1 × 1 m) digital elevation model was created by filtering and applying a multiscale curvature classification algorithm. The connectivity values show a decrease directly related to ~71% decrease of agricultural land. Understanding landscape patterns, changes and interactions of human activities is essential for land management in Mediterranean agroecosystems. Copyright © 2016 John Wiley &amp; Sons, Ltd.