Occurrence Of Fungal Diseases Research Articles

Preliminary Work on Generative Seedling Production and Clone Selection of European Black Poplar (Populus nigra L.)

European black poplar (Populus nigra L.) is a pioneer species that belongs to the Salicaceae family and occurs in riparian ecosystems. It is one of the most endangered forest species in its entire distribution area. In Croatia, black poplars are considered an economically important forest species, but mostly clones originate from crossing combinations with American and European black poplar (Populus × canadensis Moench), while a small number of clones are native black poplar. Studies on native black poplar are quite rare and the generative propagation has not been used. The aim of this study was to gain knowledge on the production of high-quality black poplar seedlings and to carry out the selection of genotypes with the aim of establishing a base for future breeding. The female black poplar tree was selected on phenotypic characteristics in the area of Forest Administration Osijek, Forest Office Valpovo. The tree was cut down in April 2019, and branches with half-open seed capsules on catkins were collected. The branches were transferred to the Croatian Forest Research Institute’s greenhouse, where the catkins opened under the influence of the high temperature. Sowing was done in different substrates to test their effectiveness. Black poplar seedlings were selected and transplanted with regard to development and height growth. The results showed differences in height growth between plants sown in two different substrates and the occurrence of fungal diseases only on plants sown in pure sand. With subsequent multiple propagation using cuttings and selection by genotype, it is expected that it will be possible to identify several clones of native black poplar that will be introduced for use in forestry in Croatia. The use of quality plants grown from seeds will increase the genetic diversity and preserve the native black poplar gene pool.

Occurrence of maize (Zea mays L.) diseases caused by fungi on long-term monoculture fields in south-eastern Poland in 2010–2021

The aim of the study was monitoring of the occurrence of fungal diseases of maize in south-eastern Poland. The observations were made in 2010–2021 in two fields conducted in a long-term monoculture in the Krzeczowice and Nienadówka. The health analyses were performer on the San (FAO 240) and Ronaldinio (FAO 260) maize varieties. The following maize diseases have been found: common smut of maize (Ustilago maydis), corn head smut (Sphacelotheca reiliana), eyespot (Kabatiela zeae), northern corn leaf spot (Helminthosporium spp.), common rust of maize (Puccinia sorghi), fusarium ear rot and fusarium stalk rot caused by fungi of the genus Fusarium. The most dangerous diseases are fusarium ear rot, fusarium stalk rot and common smut of maize. The most common fungal disease was eyespot. The appearance of these diseases was favored by some meteorological factors, such as hailstorm and pest feeding, especially frit fly, aphids, and European corn borer.

The Role of Water Content in the Casing Layer for Mushroom Crop Production and the Occurrence of Fungal Diseases

Mushroom cultivation requires effective control of environmental cues to obtain the best yield and high quality. The impact of water content in the casing layer on mushroom yield and the incidence of two of the most important diseases in the mushroom growing farms, dry bubble and cobweb diseases, was evaluated. Different initial water content in the casing and two alternative irrigation programs applied (light or moderate irrigation) were the agronomic parameters under study during five separate button mushroom crop trials. Higher initial humidity content in the casing layer reported a larger yield, with a fewer number of basidiomes but heavier, while no correlation to the dry matter content or the colour of the basidiomes was noted. The incidence of dry bubble disease was not conditioned by the water content of the casing layer, at the high moisture levels established in the study. In the case of Cladobotryum mycophilum, the lower moisture level of the casing layer reported more incidence of cobweb disease, and subsequently harmful yield losses. According to the results obtained, the right management of the moisture level in the casing materials could promote crop yield and preclude the significant impact of dry bubble and cobweb diseases.

Hyperspectral imaging for high-throughput vitality monitoring in ornamental plant production

Ornamental heather (Calluna vulgaris) production is characterized by high risks such as occurrence of fungal diseases and plant losses. Given the general absence of formal research on this economically important production system, farmers depend on their own approaches to assess plant vitality. We provide a reproducible, affordable and transparent workflow for assessing ornamental plant vitality with spectroscopy data. We use hyperspectral imaging as a non-invasive alternative for monitoring plant performance by combining the long-term experience of experts with hyperspectral images taken with a portable hyperspectral camera. We tested a custom-made setup deployed in a horticultural production facility and screened thousands of heather plants over a period of 14 weeks during their development from cuttings to young plants under production conditions. The vitality of shoots and roots was classified by experts for comparison with spectral signatures of shoot tips of healthy and stressed plants. To identify wavelengths that allow distinguishing between healthy and stressed heather plants, we evaluated the datasets using Partial Least Squares regression. Reflectance in the green (519–575 nm) and red-edge (712–718 nm) region of the spectrum was identified as most important for classifying plants as healthy or stressed. We transferred the trained Partial Least Squares regression model to independent test data obtained on a different date, correctly classifying 98.1% of the heather plants. The setup we describe here is adjustable and can be used to measure different plant species. We identify challenges in data evaluation, point out promising evaluation approaches, and make our dataset available to facilitate further studies on plant vitality in horticultural production systems.

Weather and distance to fire refugia limit landscape‐level occurrence of fungal disease in an exotic annual grass

AbstractThe enemy release hypothesis proposes that invasion by exotic plant species is driven by their release from natural enemies (i.e. herbivores and pathogens) in their introduced ranges. However, in many cases, natural enemies, which may be introduced or managed to regulate invasive species, may fail to impact target host populations. Landscape heterogeneity, which can affect both the population dynamics of the pathogen and the susceptibility and the density of hosts, may contribute to why pathogens fail to control hosts despite established negative disease impacts.We explored patterns of post‐fire infection of the fungal head‐smut pathogenUstilago bullataon the invasive annual cheatgrassBromus tectorum, which has caused the notorious grass‐fire cycle and ecosystem degradation across Western North America. We asked whether infection level was a driver of host density or vice‐versa, and how weather affected infection and how spatial patterns of infection varied with time since fire, using a combination of structural equation modelling (SEM), proportional odds modelling and entropy‐based local indicator of spatial association (ELSA) on data from >700 plots spanning >100,000 ha remeasured annually for 4 years.Observed infection levels increased with greater prior‐year cheatgrass cover, and disease severity did not suppress cheatgrass populations. Warm, humid fall/winters and proximity to fire refugia (unburned patches) were associated with more infections. Infection clustering was most evident 2–3 years following fire with warm‐wet fall–winter conditions and decreased after two drier, colder winters.Synthesis. Severity of fungal disease did not result in measurable reductions of populations of a non‐native, invasive host species, cheatgrass, which suggests that natural enemies may not strongly regulate cheatgrass in its introduced range. Landscape heterogeneity associated with disturbance and weather limited population‐level infection of hosts by the fungal pathogen. Disturbance (specifically wildfire) and variable weather are key components of this and similar invasion systems, and likely need to be considered when evaluating disease dynamics and potential for natural enemies to influence invasion potential.

Occurrence of fungal diseases in faba bean (Vicia faba L.) under salt and drought stress

The present work was initiated in order to test whether the growth and pathogenic behavior of fungal isolates infecting Faba bean (FB) are influenced by salt and drought stress. A collection of 108 fungal isolates was recovered from different infected FB plants grown in various bioclimatic zones in Tunisia. Koch’s postulates revealed that 54% of those isolates caused root rots infection by 25% to 100% of the whole root system. Eighteen pathogenic fungal isolates were chosen based on their high incidence on various plant growth parameters using the heat map analysis to undergo the in vitro analysis, where 13 isolates belong to Fusarium spp. The in vitro mycelial growth of the 18 strains in potato-dextrose agar amended with NaCl and PEG6000 was strain dependent, in which F. equiseti (VFF12, VFF16), F. graminearum VFF6, F. brachygibbosum VFF9, Alternaria sp. VFF5, Boeremia exigua VFF4, Rutstroemia sp. VFF7 and Rhizopus oryzae VFF1 showed a significant increase by up to 150% compared to controls. Best linear unbiased predictors (BLUPs) for differences in root and shoot dry weights between control (inoculated unstressed plants) and inoculated under salt and drought stress of the tolerant fungal strains were analyzed. BLUPs of VFF16, VFF6, and VFF7 were significantly increased under both stresses compared to controls. While, BLUBs of VFF12, VFF9, and VFF4 were not significant, which maintained similar pathogenic effect. However, BLUPs of VFF5 and VFF1 were significantly decreased. Consequently, soil salinization and water deficiency - occurring nowadays in many parts of the world - can increase the aggressiveness of phytopathogenic fungi.

The evaluation of infection caused by different fungi species of highbush blueberry plants grown on selected commercial plantations located in central Poland

W latach 2017–2018 prowadzono badania dotyczące wy-stępowania chorób powodowanych przez grzyby na czterech plantacjach borówki wysokiej zlo-kalizowanych w centralnej Polsce. Celem badańbyła izolacja i identyfikacja patogenów z pora-żonych organów krzewów borówki wysokiej. W badanym materiale roślinnym zidentyfikowano cztery gatunki grzybów. Na wszystkich lustrowa-nych plantacjach obserwowano Botrytis cinerea, Godronia cassandrae i Phomopsis vaccinii, a tyl-ko na jednej plantacji zidentyfikowano Valdensia heterodoxa. Grzyby identyfikowano na podstawie oznak etiologicznych obecnych na porażonych organach roślin, przy użyciu klasycznych metod. W ramach badań oceniono skuteczność siedmiu fungicydów w zwalczaniu choroby szara pleśńborówki wysokiej. Do badań wykorzystano za-równo preparaty powszechnie polecane w ochro-nie borówki wysokiej przed szarą pleśnią, jak i fungicydy dopuszczone do ochrony przed tą cho-robą upraw innych roślin jagodowych (truskawka i malina). Fungicydy Luna Experience 400 SC i Prolectus 50 WG mogą być rozważane jako uzu-pełnienie listy środków zalecanych do zwalczania choroby szara pleśń na plantacjach borówki wy-sokiej.

Screening and Biochemical Characterization of Wheat Cultivars Resistance to Magnaporthe oryzae pv Triticum (MoT)

Global food security is seriously threatened due to increased frequency and occurrence of fungal diseases. One example is wheat blast caused by Magnaporthe oryzae is a fungal diseases of rice, wheat, and other grasses, that can destroy the whole food production to sustain millions of people. Wheat blast was first detected in february 2016 with a serious outbreak in Asia. Assessment of the available germplasms to stress tolerant/resistant is one of the best options for developing stress tolerant crop varieties. In this study, a total of sixteen wheat cultivars were collected and test their disease severity to blast pathogen Magnaporthe oryzae pv. Triticum (MoT). Among the varieties, BARI Gom 33 exhibited partially resistance against blast pathogen, whereas all other genotypes become susceptible to MoT. Different yield and yield contributing characters of both resistant and susceptible cultivars were also evaluated and found no significant differences among them. To understand the underlying mechanism of resistance in BARI Gom 33, antioxidant enzyme activity, concentration of reactive oxygen species and cellular damage after fungal infection were also evaluated and found that activities of ascorbate peroxidase (APX), catalase (CAT) and peroxidase (POD) were higher in BARI Gom 33 than BARI Gom 25 and BARI Gom 31. The hydrogen peroxide (H2O2) and malondealdehyde (MDA) content in BARI Gom 33 was low compare to BARI Gom 25 and BARI Gom 31, which may due to greater increase of the APX, CAT and POD in resistant genotypes. Thus, it may suggest that a more efficient antioxidative defense system in BARI Gom 33 during the infection process of M. oryzae restricts the cell damage caused by the fungus. The identified genotypes can either be used directly in the blast prone area or as a source of resistance to further development of blast resistance high yielding wheat variety.

Detection Methods of Fungi in Ilex paraguariensis Seeds

Abstract There has been an increase in the occurrence of fungal diseases in Ilex paraguariensis A. St.-Hill. (yerba mate) resulting from their domestication. Seed health tests may indicate pathogens prior to sowing, enabling their control. Our study sought to compare the efficacy of fungi detection methods on yerba mate seeds. Seeds from four lots were subjected to the following detection methods: BDA, V8 and filter paper; as well as the performance of asepsis with 1% sodium hypochlorite and 70% alcohol. The fungi found in the lots were: Penicillium spp., Cladosporium spp., Aureobasidium melanogenum, Aspergillus spp., Pestalotia spp., Nigrospora spp., Trichoderma spp., Fusarium graminearum, F. oxysporum and F. guttiforme. The asepsis in the seeds reduced the occurrence of contaminating organisms. There were differences between the evaluated lots regarding fungal incidence. In general, the BDA and V8 culture media showed better results in fungal detection.

Analysis of Climatic Risk Favorability of Grapevine Fungal Disease Occurrence for Santa Teresa, Espírito Santo State, Brazil

The State of Espírito Santo, Brazil, has micro-regions with different climatic and soil conditions, which promote grapevine cultivation vine in several municipalities. However, the grape production process is strongly threatened by foliar fungal diseases, and its control increases the cost of production significantly. In turn, the use of models of prediction of disease occurrence allows the identification of regions with climatic risk potential for grapevine. Hence, the objective of this work was to analyze the agro-climatic favorability of climatic risk for occurrence of fungal diseases of downy mildew (Plasmopara viticola) and Botrytis cinerea on the grapevine for the municipality of Santa Teresa, in the state of Espírito Santo. Predictive models of favorability of downy mildew and B. cinerea were used. The number of sprayings was determined by the calendar system and by the rainfall system, according to the length of the cycle. Therefore, a series of meteorological data from 2007 to 2016 was used. The results showed that the frequency of days with low risk of mildew was 2%, medium risk 5%, high risk 93%. For B. cinerea, these values were 32%, 68%, and 0%, with low, medium and high risk, respectively. The number of required sprayings, according to the weather conditions, was lower than the number of sprayings recommended by the calendar system. The relationship between the risk of occurrence of the evaluated diseases showed a higher agro-meteorological favorability of occurrence of mildew in relation to B. cinerea.

Field performance of five white Pilzwiderstandsfahige (PIWI) cultivars in the south of Brazil

Southern Brazil is the largest grape-producing region in the country. It is characterized by the production of labrusca grapes, because of the difficulty of growing Vitis vinifera. This can be explained by the high occurrence of fungal diseases, especially downy mildew, which is favored by the environmental conditions (high temperatures, relative humidity and rainfall). Pilzwiderstandsfahige (PIWI) are a group of wine-grape cultivars similar to V. vinifera but with resistance to downy and powdery mildew. These cultivars open the possibility of reducing production cost and agrochemical sprays for viticulture in Brazil. In order to achieve this objective, studies related to phenological, productive and qualitative characteristics are necessary. A PIWI cultivar trial was established in 2015, in the city of Videira, Santa Catarina State, Brazil, with five white cultivars. The vines were trained in vertical shoot position (VSP) trellis and pruned in double cordons. The studied cultivars were ‘Felicia’, ‘Calardis Blanc’, ‘Helios’, ‘Bronner’ and ‘Aromera’, grafted on ‘Paulsen 1103’. The variables evaluated were phenology, incidence of downy mildew, yield, number of clusters, average cluster weight, total soluble solids, pH and total titratable acidity. In terms of productivity, the outstanding cultivars were ‘Felicia’ and ‘Calardis Blanc’, with yields above the traditional V. vinifera cultivars. ‘Felicia’ was the earliest cultivar and produced the heaviest clusters. ‘Calardis Blanc’ presented the largest number of clusters, and ‘Aromera’ was the latest cultivar. Soluble solids contents, pH and acidity were adequate in all cultivars. In general, all tested cultivars showed good potential for the studied region.

Occurrence of fungal diseases caused by fungi on faba bean (Vicia faba L. var. minor Harz.) plants in different regions of Poland

Occurrence of fungal diseases caused by fungi on faba bean (Vicia faba L. var. minor Harz.) plants in different regions of Poland

Występowanie chorób grzybowych na roślinach łubinu wąskolistnego (Lupinus angustifolius L.) w różnych rejonach Polski

Summary The aim of the study was to evaluate the degree of blue lupine (Lupinus angustifolius L.) infestation by pathogenic fungi, in particular regions of Poland, in dependence on cultivar and course of weather conditions. An experiment was conducted at the Stations of Research Centre for Cultivar Testing located in the following provinces: zachodniopomorskie, wielkopolskie, lubelskie, kujawsko-pomorskie, mazowieckie, podlaskie, podkarpackie, warminsko-mazurskie and pomorskie. Sixteen cultivars of blue lupine with different resistance to pathogenic fungi were included in this study. It was found that the occurrence of fungal diseases on blue lupine plants varied in particular regions of Poland. Root rot (Fusarium oxysporum, Rhizoctonia solani and others) and white mould (Sclerotinia sclerotiorum) occurred at the highest severity while wilting of lupine (F. oxysporum) and particularly seed borne anthracnose (Colletotrichum ssp.) appeared at considerably lower intensity. It has been proved that there is a clear dependence between fungal disease development and course of weather conditions as well as between infestation of plants by pathogenic fungi and collected yield. Among analyzed pathogens Colletotrichum ssp. and Fusarium oxysporum had the greatest impact on the blue lupine yield.

Germination of seeds of Avena fatua L. under different storage conditions

Storage conditions have a strong influence on the germination of seeds of <em>Avena fatua</em> L, especially at variable conditions, the germination decreased. Seeds stored at a constant low temperature maintained the germination capability for 5 years. Under greenhouse conditions, seeds matured and germinated more rapidly comparing to field conditions, but individuals from these seeds were weaker and produced fewer seeds. The higher temperature in the greenhouse accelerated the development and maturing of plants. Field emergence varied depending on seed storage conditions, sample, further reproduction, and weather conditions. It was observed that individual specimens of <em>A. fatua</em> were able to form ripe seeds with high thousand grain mass (TGM), regardless of the occurrence of fungal diseases. The knowledge of the biology of <em>A. fatua</em> is very important due to its status as a restricted weed in certified seed of crop plants.

A DEHUMIDIFYING HEAT PUMP FOR GREENHOUSES

In heated greenhouses, attempts have been made to produce potted plants while reducing the amount of energy used. In fact, improvements in greenhouse structure and equipment (double walls, etc.) have led to better insulation and tightness. However, this tightness induces microclimatic changes, especially on night time humidity levels. The increase of indoor humidity leads to the development of condensation and dripping and, consequently, to the increase in the occurrence of fungal diseases and physiological disorders. It is therefore necessary to decrease the humidity in the air. To do this, growers have to dehumidify the air by ventilation-heating, involving a major increase in energy consumption. Humidity control is therefore a limiting factor for saving energy, making it necessary to find alternatives to the ventilation-heating method used to reduce indoor humidity. We analyzed the effectiveness of a dehumidifying heat pump installed in a 2350-m(2) double wall inflatable greenhouse located in northwestern France, during spring 2010. Hydrangeas in containers were placed on the ground (heated). The temporal evolution of climatic, thermodynamic and ecophysiological data is presented and analyzed. The thermodynamic efficiency of the machine is also taken into account. Depending on the weather outside, the energy consumption of the device (power: 4W m(-2)) used to dehumidify the air is three to four times lower than that which would have been used by the ventilation-heating method. By condensing approximately 30 L of water per hour during the operating phase of the heat pump, the machine balances crop evapotranspiration and avoids condensation and the occurrence of fungal diseases.

Produção e características físico-químicas dos cachos da videira 'BRS Clara' sob cobertura plástica e sombrite em safra fora de época

Devido às condições climáticas favoráveis à ocorrência de doenças fúngicas em uvas de mesa, tem-se buscado a adoção de tecnologias que propiciem a redução nos custos de produção, sendo uma alternativa o cultivo de uvas sob cobertura plástica. O objetivo deste trabalho foi avaliar a produção e as características físico-químicas dos cachos da videira 'BRS Clara' enxertada sobre o porta-enxerto IAC-766 'Campinas', em cultivo protegido durante a safra fora de época, visando à redução da aplicação de fungicidas para o controle do míldio. Os experimentos foram realizados em pomares comerciais localizados em Uraí e Marialva-PR. As videiras foram conduzidas no sistema latada, em espaçamento de 4,0 x 4,0 m, em Uraí, e de 2,0 x 5,0 m, em Marialva. O delineamento experimental foi o inteiramente casualizado, com dois sistemas de cultivo protegido (sob cobertura plástica e sob sombrite) e sete repetições. No experimento conduzido em Uraí, não foram verificadas diferenças entre os sistemas de cultivo protegido quanto às características produtivas e químicas das bagas, como o teor de sólidos solúveis totais, índice de maturação e pH. Verificou-se a ocorrência do míldio somente nas folhas, sendo a incidência e a severidade menor nas videiras sob cobertura plástica (0,5 e 0,02%, respectivamente). Em Marialva, também não houve influência das coberturas nas características produtivas das videiras. Entretanto, o teor de sólidos solúveis totais das bagas sob cobertura plástica foi superior em relação àquelas sob sombrite (19,6 e 17,2ºBrix, respectivamente). Não foi detectada a ocorrência de míldio em nenhum dos sistemas de cultivo protegido nessa localidade. Conclui-se que o uso da cobertura plástica permite a redução do número de aplicações de fungicidas para o controle do míldio, sem alterar as características produtivas da uva 'BRS Clara'.

Occurrence of fungal diseases on angelica (Archangelica officinalis Hoffm.) in the region of Małopolska

The field experiment on angelica (<i>Archangelica officinalis</i> Hoffm.) was carried out in the years 2001-2002 at the plantations situated in Małopolska (Mydlniki near Kraków and Królówka near Bochnia). The results of two years' investigations pointed out, that angelica plants during vegetation were infested by many pathogens. The most often noticed on the plants were angelica rust (<i>Puccinia anglicae</i>), powdery mildew (<i>Erysiphe umbelliferarum</i>) and Cercospora leaf spot (<i>Cercospora</i> sp.). Moreover, many various types of disease symptoms, which were described and made a diagnosis. There were mainly spots on leaves and steams, from which there were isolated most often fungi from <i>Alternaria</i> genus. The investigations on the salubrity of the seed material (angelica fruits) coming from different sources showed that fungi from genus <i>Alternaria</i> were likely to transfer by seeds and caused disease symptoms on plants during vegetation. Fungi from genus <i>Alternaria</i> were most often isolated from angelica fruits. Saprotrophic fungi (<i>Epicoccum purpurascens</i>, <i>Penicillium</i> spp., <i>Mucor hiemalis</i>) were also often isolated from angelica fruits. Disinfection on fruits reduced number of isolated fungi and bacteria.

Influence of fungicide protection on health status and yielding of winter wheat

The aim of the study was the effect of different chemical protection of winter wheat on occurrence of fungal diseases of stem base, leaves and yield as well. In 1999-2001 cultivars Roma and Kobra were tested in Lisewo and Wielgłowy in northern Poland. There was one fungicide treatment with kresoxim-methyl and epoxyconazole during phase 39-49 and two treatments, first with kresoxim-methyl + epoxyconazole in phase 32 and the second with tridemorf + epoxyconazole in phase 51-55. In 2002-2004 the experiment was continued in Wielgłowy on cultivar Kobra with protection combinations as follows: first treatment with kresoxim-methyl + epoxyconazole in phase 39-49, and the next ones with tridemorf + epoxyconazole or dimoksystrobine + epoxyconazole in phase 51-55. The highest infection was observed on cv. Kobra. Among pathogens isolated from infected stem bases, <i>Fusarium</i> spp. predominated, while <i>Rhizoctonia</i> spp. and <i>Mollisia yallundae</i> were less numerous. Powdery mildew was observed in relatively low or trace intensity, but complex of necrotic spots on leaves was noticed in high intensity. High occurrence of <i>Mycosphaerella graminicola</i>, <i>Phaeosphaeoria nodorum</i> and <i>Pyrenophora tritici</i>-<i>repentis</i> as well as <i>Fusarium</i> spp. was observed. Fungicide treatments were very effective in reducing occurrence of the investigated pathogens. The area of upper leaves without disease symptoms (GLA) was significantly higher in combinations with fungicides.

A MULTIFUNCTION DEHUMIDIFYING HEAT PUMP FOR GREENHOUSES

mprovements in greenhouse structure and equipment with the aim of saving energy (double walls, thermal screens) have led to better insulation and airtightness but have also induced microclimatic changes, especially on nighttime humidity levels. During the last decade, dynamic climate procedures such as temperature integration have been frequently implemented to save energy in greenhouses. Temperatures may reach low levels and the greenhouse ventilation may remain particularly weak when using these types of systems, but the humidity level is always high. Consequently, the occurrence of fungal diseases and physiological disorders increases and greenhouse air dehumidification is required. In order to cope with this problem, a multifunction compression heat was developed, first, for dehumidifying the greenhouse during the night and, second, for heating the greenhouse in the same way as that of a conventional air-source heat pump, in addition to the boiler. To reach these objectives, a second evaporator is added to draw the heat from the outside to the inside (air-air). A water condenser (air-water) may also be added to provide a low-temperature heating system. The activation of the heating mode depends on the coefficient of performance (COP) and on the economic viability (bi-energy system: depending on the main energy source used). The dehumidification heat pump is designed for use at night as a function of the vapour pressure deficit (VPD) set point. A dynamic model of water vapour exchanges was developed to evaluate during the night the water vapour transfer between the different sub-systems (heat pump evaporator, crop, inside air, roof, outside air) considered as sources and sinks of water vapour. This model makes it possible to determine the power of the dehumidification systems according to the characteristic parameters of the greenhouse, the crop and the outside climate. This device is being implemented in a glasshouse in the west of France. Adjustments are, however, still necessary to validate the model and to optimise energy efficiency.

Is productivity of cacao impeded by epiphytes? An experimental approach

The impact of epiphytes on cacao productivity was investigated in agroforests in Central Sulawesi, Indonesia. Effects of epiphyte removal on fruit-set success and eventual yields were studied on 80 trees in an experiment with a balanced full factorial design. The removal treatment had no significant effect on the eventual harvest of the cacao trees. Pollinator availability had the greatest impact on fruit-set success, whereas yields were mainly determined by site-specific factors that mediate fruit-abortion and occurrence of fungal diseases. The results illustrate that epiphytic flora dominated by non-vascular species may have no effects on cacao tree functioning and removal of non-vascular epiphytes is unnecessary for improving the productivity of cacao. Hence, farmers’ labour can be reduced and conservation of the rich biodiversity outside natural forests supported.