Cultivation of black truffle to promote reforestation and land-use stability

Cultivation of black truffle, Tuber melanosporum Vitt., has become an important agricultural alternative in rural Mediterranean regions due to its success in relatively harsh conditions, its high market value and diminishing production in natural areas. In addition, truffle cultivation requires relatively low agricultural inputs, promotes reforestation and economic restoration of rural lands and land-use stability. However, there remain major issues regarding the management practices to ensure successful black truffle production. We therefore conducted an experiment to evaluate 3 levels of irrigation based on monthly water deficit and the effects of currently applied weed control systems and fertilization. Treatment effects were evaluated by examining the mycorrhizal status of out-planted 1-yr-old Quercus ilex L. seedlings and seedling growth parameters after 18 months in 3 distinct experimental truffle plantations located in the foothills of the Spanish Pyrenees. We found that replacing one-half of the water deficit of the driest month (moderate irrigation) promoted the proliferation of T. melanosporum mycorrhizae, while high irrigation reduced fine root production and truffle mycorrhizae. Glyphosate weed control improved seedling survival by up to 16% over control seedlings without jeopardizing truffle mycorrhizae in the first year. Fertilization did not improve seedling growth or influence its mycorrhizal status. We describe the persistent relationship between this ectomycorrhizal fungus and Q. ilex by quantifying old and new mycorrhizae and we discuss the ecological implications of the symbiosis.

Isótopos estables aplicados al estudio de los sistemas paleoagrícolas mediterráneos

El origen y progresivo desarrollo de la agricultura es probablemente el primer ejemplo de interacción recíproca a gran escala entre la humanidad y el medio ambiente. Por tanto, reconstruir las condiciones ambientales que caracterizaron la adopción de la agricultura es de gran interés de cara a conocer sus causas potenciales, así como para comprender los efectos a largo plazo de la economía agrícola sobre el ambiente. En este trabajo presentamos la metodología desarrollada por nuestro equipo para reconstruir las condiciones climáticas y de cultivo en la agricultura primitiva, basada en el análisis de la composición isotópica de carbono (enriquecimiento en 13C) y nitrógeno (enriquecimiento en 15N) en restos vegetales recuperados de yacimientos arqueológicos. El análisis de 13C en cariópsides de cereales carbonizadas ha permitido cuantificar la disponibilidad hídrica de los cultivos en diversos yacimientos de la Península Ibérica y el Creciente Fértil, así como estimar su rendimiento en el pasado, mientras que el análisis de 15N, nos aporta información cualitativa sobre las condiciones nutricionales. Por otro lado, el análisis de 13C en restos forestales (carbones) ha permitido cuantificar las condiciones climáticas (precipitación y déficit hídrico) en los mismos yacimientos, aportando así información sobre el marco climático en el que se desarrollaron los cultivos.

Regulated irrigation of woody ornamentals to improve plant quality and precondition against drought stress

Regulated irrigation has the potential to improve crop quality in woody ornamentals by reducing excessive vigour and promoting a more compact habit. This research aimed to compare the effectiveness and the mode of action of two techniques, regulated deficit irrigation (RDI) and partial root drying (PRD), when applied to container-grown ornamentals through drip irrigation. Results showed that RDI and PRD reduced growth in Cotinus coggygria 'Royal Purple', but in Forsythia x intermedia 'Lynwood', significant reductions were recorded only with RDI. Physiological measurements in Forsythia indicated that reductions in stomatal conductance (g(s)) occurred in both treatments, but those in the RDI tended to be more persistent. Reduced g(s) in PRD was consistent with the concept that chemical signals from the root can regulate stomatal aperture alone; however, the data also suggested that optimising the growth reduction required a moderate degree of shoot water deficit (i.e. a hydraulic signal to be imposed). As RDI was associated with tissue water deficit, it was used in a second experiment to determine the potential of this technique to precondition container-grown plants against subsequent drought stress (e.g. during retail stages or after planting out). Speed of acclimation would be important in a commercial context, and the results demonstrated that both slow and rapid imposition of RDI enabled Forsythia plants to acclimate against later drought events. This article discusses the potential to both improve ornamental plant quality and enhance tolerance to subsequent adverse conditions through controlled, regulated irrigation.

Assessing the vulnerability of blanket peat to climate change using an ensemble of statistical bioclimatic envelope models

We assessed the vulnerability of blanket peat to climate change in Great Britain using an ensemble of 8 bioclimatic envelope models. We used 4 published models that ranged from simple threshold models, based on total annual precipitation, to Generalised Linear Models (GLMs, based on mean annual temperature). In addition, 4 new models were developed which included measures of water deficit as threshold, classification tree, GLM and generalised additive models (GAM). Models that included measures of both hydrological conditions and maximum temperature provided a better fit to the mapped peat area than models based on hydrological variables alone. Under UKCIP02 projections for high (A1F1) and low (B1) greenhouse gas emission scenarios, 7 out of the 8 models showed a decline in the bioclimatic space associated with blanket peat. Eastern regions (Northumbria, North York Moors, Orkney) were shown to be more vulnerable than higher-altitude, western areas (Highlands, Western Isles and Argyle, Bute and The Trossachs). These results suggest a long-term decline in the distribution of actively growing blanket peat, especially under the high emissions scenario, although it is emphasised that existing peatlands may well persist for decades under a changing climate. Observational data from long-term monitoring and manipulation experiments in combination with process-based models are required to explore the nature and magnitude of climate change impacts on these vulnerable areas more fully.

Assessment of projected changes in upland environments using simple climatic indices

Climate controls upland habitats, soils and their associated ecosystem services; therefore, understanding possible changes in upland climatic conditions can provide a rapid assessment of climatic vulnerability over the next century. We used 3 different climatic indices that were optimised to fit the upland area classified by the EU as a Severely Disadvantaged Area (SDA) 1961–1990. Upland areas within the SDA covered all altitudinal ranges, whereas the maximum altitude of lowland areas outside of the SDA was ca. 300 m. In general, the climatic index based on the ratio between annual accumulated temperature (as a measure of growing season length) and annual precipitation predicted 96% of the SDA mapped area, which was slightly better than those indices based on annual or seasonal water deficit. Overall, all climatic indices showed that upland environments were exposed to some degree of change by 2071–2100 under UKCIP02 climate projections for high and low emissions scenarios. The projected area declined by 13 to 51% across 3 indices for the low emissions scenario and by 24 to 84% for the high emissions scenario. Mean altitude of the upland area increased by +11 to +86 m for the low scenario and +21 to +178 m for the high scenario. Low altitude areas in eastern and southern Great Britain were most vulnerable to change. These projected climatic changes are likely to affect upland habitat composition, long-term soil carbon storage and wider ecosystem service provision, although it is not yet possible to determine the rate at which this might occur.

Sub-irrigation of Petunia: benefits in dry summers

With the increasing frequency and magnitude of warmer days during the summer in the UK, bedding plants which were a traditional part of the urban green landscape are perceived as unsustainable and water-demanding. During recent summers when bans on irrigation have been imposed, use and sales of bedding plants have dropped dramatically having a negative financial impact on the nursery industry. Retaining bedding species as a feature in public and even private spaces in future may be conditional on them being managed in a manner that minimises their water use. Using Petunia x hybrida ‘Hurrah White’ we aimed to discover which irrigation approach was the most efficient for maintaining plants’ ornamental quality (flower numbers, size and longevity), shoot and root growth under water deficit and periods of complete water withdrawal. Plants were grown from plugs for 51 days in wooden rhizotrons (0.35 m (h) x 0.1 m (w) x 0.065 m (d)); the rhizotrons’ front comprised clear Perspex which enabled us to monitor root growth closely. Irrigation treatments were: 1. watering with the amount which constitutes 50% of container capacity by conventional surface drip-irrigation (‘50% TOP’); 2. 50% as sub-irrigation at 10 cm depth (‘50% SUB’); 3. ‘split’ irrigation: 25% as surface drip- and 25% as sub-irrigation at 15 cm depth (‘25/25 SPLIT’); 4. 25% as conventional surface drip-irrigation (‘25% TOP’). Plants were irrigated daily at 18:00 apart from days 34-36 (inclusive) when water was withdrawn for all the treatments. Plants in ‘50% SUB’ had the most flowers and their size was comparable to that of ‘50% TOP’. Differences between treatments in other ‘quality’ parameters (height, shoot number) were biologically small. There was less root growth at deeper soil surface levels for ‘50% TOP’ which indicated that irrigation methods like ‘50% SUB’ and ‘25/25 SPLIT’ and stronger water deficits encouraged deeper root growth. It is suggested that sub-irrigation at 10 cm depth with water amounts of 50% container capacity would result in the most root growth with the maximum flowering for Petunia. Leaf stomatal conductance appeared to be most sensitive to the changes in substrate moisture content in the deepest part of the soil profile, where most roots were situated.

Morpho-physiological characterization of spring wheat genotypes under drought stress

Water-deficit is a severe abiotic stress and major constraint to wheat productivity with effect on plant growth and development. The objective of this study was to characterize drought tolerant and susceptible spring wheat cultivars on the basis of physiological and yield attributes. The experiment was comprised of two irrigation regimes i.e. irrigated and 65% drought stress and ten wheat cultivars viz. Anmol, Moomal, Sarsabz, Bhittai, Pavon, SKD-1, TD-1, Kiran, Marvi and Mehran. Results indicated significant effect of water stress on stomatal dimension, stomatal conductance, relative leaf water content and grain yield with no effect on stomatal density. The irrigation × cultivars interaction was non-significant for grain yield only. Cultivars like Anmol, Moomal, Bhittai, Sarsabz proved to be drought tolerant with smaller stomatal dimensions, less stomatal conductance and more relative water content under water stress and produced higher grain yield. While decrease in relative water contents and grain yield, and increase in stomatal attributes was observed in drought susceptible cultivars such as Marvi, TD-1 and SKD-1 hence proved to be drought susceptible.

Use of synteny to identify candidate genes underlying QTL controlling stomatal traits in faba bean (Vicia faba L.)

Key message We have identified QTLs for stomatal characteristics on chromosome II of faba bean by applying SNPs derived from M. truncatula , and have identified candidate genes within these QTLs using synteny between the two species. Abstract Faba bean (Vicia faba L.) is a valuable food and feed crop worldwide, but drought often limits its production, and its genome is large and poorly mapped. No information is available on the effects of genomic regions and genes on drought adaptation characters such as stomatal characteristics in this species, but the synteny between the sequenced model legume, Medicago truncatula, and faba bean can be used to identify candidate genes. A mapping population of 211 F5 recombinant inbred lines (Mélodie/2 × ILB 938/2) were phenotyped to identify quantitative trait loci (QTL) affecting stomatal morphology and function, along with seed weight, under well-watered conditions in a climate-controlled glasshouse in 2013 and 2014. Canopy temperature (CT) was evaluated in 2013 under water-deficit (CTd). In total, 188 polymorphic single nucleotide polymorphisms (SNPs), developed from M. truncatula genome data, were assigned to nine linkage groups that covered ~928 cM of the faba bean genome with an average inter-marker distance of 5.8 cM. 15 putative QTLs were detected, of which eight (affecting stomatal density, length and conductance and CT) co-located on chromosome II, in the vicinity of a possible candidate gene—a receptor-like protein kinase found in the syntenic interval of M. truncatula chromosome IV. A ribose-phosphate pyrophosphokinase from M. truncatula chromosome V, postulated as a possible candidate gene for the QTL for CTd, was found some distance away in the same chromosome. These results demonstrate that genomic information from M. truncatula can successfully be translated to the faba bean genome.

Fluxes of CO(2) above a plantation of Eucalyptus in southeast Brazil

Eddy-covariance measurements of net ecosystem exchange of CO(2) (NEE) and estimates of gross ecosystem productivity (GEP) and ecosystem respiration (R(E)) were obtained in a 2-4 year old Eucalyptus plantation during two years with very different winter rainfall In the first (drier) year the annual NEE GEP and RE were lower than the sums in the second (normal) year and conversely the total respiratory costs of assimilated carbon were higher in the dry year than in the normal year Although the net primary production (NPP) in the first year was 23% lower than that of the second year the decrease in the carbon use efficiency (CUE = NPP/GEP) was 11% and autotrophic respiration utilized more resources in the first dry year than in the second normal year The time variations in NEE were followed by NPP because in these young Eucalyptus plantations NEE is very largely dominated by NPP and heterotrophic respiration plays only a relatively minor role During the dry season a pronounced hysteresis was observed in the relationship between NEE and photosynthetically active radiation and NEE fluxes were inversely proportional to humidity saturation deficit values greater than 0 8 kPa Nighttime fluxes of CO(2) during calm conditions when the friction velocity (u) was below the threshold (0 25 ms(-1)) were estimated based on a Q(10) temperature-dependence relationship adjusted separately for different classes of soil moisture content which regulated the temperature sensitivity of ecosystem respiration (C) 2010 Elsevier B V All rights reserved

Extended time weather forecasts contributes to agricultural productivity estimates

Weather conditions in critical periods of the vegetative crop development influence crop productivity, thus being a basic parameter for crop forecast. Reliable extended period weather forecasts may contribute to improve the estimation of agricultural productivity. The production of soybean plays an important role in the Brazilian economy, because this country is ranked among the largest producers of soybeans in the world. This culture can be significantly affected by water conditions, depending on the intensity of water deficit. This work explores the role of extended period weather forecasts for estimating soybean productivity in the southern part of Brazil, Passo Fundo, and Londrina (State of Rio Grande do Sul and Parana, respectively) in the 2005/2006 harvest. The goal was to investigate the possible contribution of precipitation forecasts as a substitute for the use of climatological data on crop forecasts. The results suggest that the use of meteorological forecasts generate more reliable productivity estimates during the growth period than those generated only through climatological information.

Desiccation tolerance in Pleurostima purpurea (Velloziaceae)

Previous works suggested that Pleurostima purpurea (Velloziaceae-Barbacenioideae) shows a remarkable capacity to endure desiccation of its vegetative tissues. P. purpurea occurs in monocotyledons mats on soil islands in the Pao de Acucar (Sugar Loaf) one of the most recognizable rock outcrops of the world, in Rio de Janeiro, southeastern Brazil. Mats of P. purpurea occur in cliffs by the sea some meters above the tidal zone. Although living in rock outcrops almost devoid of any soil cover, P. purpurea seems to occur preferably on less exposed rock faces and slightly shady sites. Usually, less extreme adaptations to drought would be expected in plants with the habitat preference of P. purpurea. Relying on this observation, we argue if a combination of different strategies of dealing with low water availability can be found in P. purpurea as on other desiccation tolerant angiosperms. This study aims to examine the occurrence of desiccation tolerant behavior in P. purpurea together with the expression of drought avoidance mechanisms during dehydration progression. For this, it was analyzed the gas exchanges, leaf pigments and relative leaf water content during desiccation and rehydration of cultivated mature individuals. P. purpurea behaved like typical drought avoiders under moderated drought condition with stomatal closure occurring around a relative leaf water content up to 90%. During this process, it was observed a delay in the leaf relative water content (RWC(leaf)) decrease comparing to the plant-soil relative water content (RWC(plant-soil)). As soil dehydration worsened, gas exchanges restrictions progressed until a lack of activity which characterizes anabiosis. The loss of chlorophyll occurs before the end of total dehydration, characterizing the presence of poikilochlorophylly. The chlorophyll degradation follows the RWC(leaf) decrease, which achieved the minimum average value of 17% without incurring in leaf abscission. The chlorophyll re-synthesis seems to start well after the full rehydration of the leaf. During all of this process, carotenoid content remained stable. These results are coherent with a combination of drought avoidance and desiccation tolerance in P. purpurea which seems to be coherent with the amplitude of water availability in the rock outcrop habitat where it occurs, suggesting that the periods of water availability are sufficiently long for the success of the costly desiccation tolerant behavior but too short to make a typical drought avoider species win the competition for exploring the rock outcrop substrate where P. purpurea occurs.

Aspectos germinativos de capim-camalote (Rottboellia cochinchinensis)

O capim-camalote (Rottboellia cochinchinensis), originário da Índia, é encontrado em várias regiões do mundo, sendo uma espécie temida pelos agricultores devido ao seu difícil controle e avanço crescente. Objetivou-se com este trabalho estudar os fatores que afetam a germinação das sementes dessa espécie. Foram avaliados os métodos de superação de dormência: 1 - escarificação mecânica, 2 - escarificação química, 3 - tratamento pré-semeadura, 4 - tratamento químico, 5 - tratamento hormonal e 6 - sementes não tratadas. Foram estudados os efeitos da temperatura (5, 10, 15, 20, 25, 30, 35 e 40 ºC), do fotoperíodo (6, 8, 10, 12, 14 e 16 horas de luz), da qualidade da luz incidente (branca, vermelha, vermelha distante, amarela, verde, azul e ausência de luz), da disponibilidade de água (0,0, -0,2, -0,3, -0,4, -0,5, -0,6, -1,2 e -2,4 MPa) e da viabilidade de suas sementes quando armazenadas sob condições de câmara fria e seca e sob condições naturais. Todos os ensaios foram conduzidos por 30 dias em câmara de germinação, com os tratamentos arranjados em delineamento experimental inteiramente casualizado, em quatro repetições. Verificou-se que as sementes apresentaram elevado índice de germinação, praticamente não apresentaram dormência e não se mostraram fotoblásticas. A disponibilidade de água foi indispensável para a germinação, com temperatura ideal de 25 °C. As sementes recém-coletadas são inviáveis para o estudo da germinação, apresentando redução na germinação quando armazenadas sob condição de câmara fria e seca.

Efeito simultâneo da deficiência hídrica e do alumínio tóxico no solo na cultivar IAC91-5155 de cana-de-açúcar

Sugarcane is a very important economic crop in Brazil. The effects of abiotic stresses cause negative reduction of the productivity in the sugarcane industry. In order to identify indicators of stresses tolerance, two physiological variables were evaluated, nitrate reductase activity and chlorophyll contents in young plants of sugarcane, cv. IAC91-5155. The simultaneous effect of abiotic stresses of high occurrence in Brazilian soils are, water deficiency and aluminum toxicity. The plants were submitted to three treatments of water availability (% field capacity, FC): no stress (70% FC), moderate stress (55% FC), and extreme stress (40% FC); and three acidity treatments in the soil (base saturation, V%): no acidity (V=55%), average acidity (V=33%), and high acidity (V=23%). The experiment was carried out in greenhouse, with 29.7 +/- 4.3 degrees C and 75 +/- 10% RH. The experimental design was in randomized blocks, in 3x3 factorial arrangement, with four replicates. After 60 days, nitrate reductase activity and chlorophyll contents were evaluated in the diagnostic leaf. The results demonstrate that the response of plants to a combination of drought and aluminum toxicity, similar to the conditions in many natural environments, is different from the response of plants to each of these stresses applied individually, as typically tested in the laboratory. The nitrate reductase activity can be used as a biochemical-physiological marker of water deficiency while chlorophyll contents can be used as a biochemical-physiological marker of both of them, water deficiency or aluminum toxicity in soil. Both parameters can not be as a biochemical-physiological marker for acclimation of young plants of sugarcane cv. IAC91-5155, under the combined stresses.

Efeito de diferentes períodos de irrigação no desenvolvimento, produção e qualidade de sementes na cultura do milho (Zea mays L.)

O presente trabalho foi realizado em área demonstrativa de irrigação do Departamento de Engenharia Rural da Faculdade de Ciências Agrárias e Veterinárias, da Universidade Estadual Paulista (FCAV/UNESP), Jaboticabal - SP, tendo como objetivo avaliar os efeitos da deficiência hídrica no desenvolvimento da planta, na produção e na qualidade fisiológica de sementes da cultura do milho (Zea mays L.). O delineamento experimental foi o inteiramente casualizado, com os tratamentos em esquema fatorial 2 x 3, com quatro repetições. Os tratamentos consistiram da utilização de sementes de milho híbrido BR201 e DINA-70, com três períodos de irrigação: 1) durante todo o ciclo; 2) após o período vegetativo (após a emissão da 12ª folha), e 3) até 20 dias após o florescimento (antes do período de enchimento dos grãos). Concluiu-se que a deficiência hídrica durante o período vegetativo (irrigação após a emissão da 12ª folha) foi a mais prejudicial à cultura e à produção; essa deficiência hídrica não afetou a qualidade fisiológica das sementes produzidas, e o híbrido DINA-70 apresentou melhores resultados para os parâmetros fisiológicos e de produção que o híbrido BR201.

Effects of Silicon and Drought Stress on Tuber Yield and Leaf Biochemical Characteristics in Potato

Silicon has beneficial effects on many crops, mainly under biotic and abiotic stresses. Silicon can affect biochemical, physiological, and photosynthetic processes and, consequently, alleviates drought stress. However, the effects of Si on potato (Solanum tuberosum L.) plants under drought stress are still unknown. The objective of this study was to evaluate the effect of Si supply on some biochemical characteristics and yield of potato tubers, either exposed or not exposed to drought stress. The experiment was conducted in pots containing 50 dm(3) of a Typic Acrortox soil (33% clay, 4% silt, and 63% sand). The treatments consisted of the absence or presence of Si application (0 and 284.4 mg dm(-3)), through soil amelioration with dolomitic lime and Ca and Mg silicate, and in the absence or presence of water deficit (-0.020 MPa and -0.050 MPa soil water potential, respectively), with eight replications. Silicon application and water deficit resulted in the greatest Si concentration in potato leaves. Proline concentrations increased under lower water availability and higher Si availability in the soil, which indicates that Si may be associated with plant osmotic adjustment. Water deficit and Si application decreased total sugars and soluble proteins concentrations in the leaves. Silicon application reduced stalk lodging and increased mean tuber weight and, consequently, tuber yield, especially in the absence of water stress.