Substrate Moisture Research Articles

Substrate, moisture, temperature and seed germination of the threatened endemic tree Eriotheca vargasii (Malvaceae)

We studied the germination of Eriotheca vargasii (Malvaceae), a poorly known endemic Peruvian Andean tree species characteristic of the dry forests of the Torobamba river valley. We determined seed characteristics, embryo morphology, viability, and assessed the influence of substrate (natural soil and commercially prepared media), temperature (controlled at 25 ºC and at ambient temperature between 18-22 ºC), and moisture (25 % and 50 % field capacity) on seed germination. Although most seeds were ovoid in shape and contained well-developed embryos, only 46% of them were viable. Substrate moisture levels had no influence on germination capacity or rate. In contrast, temperature and substrate type showed strong effects on germination. We observed the highest proportion of germinated seeds in prepared media at both temperatures tested (> 61 %). Furthermore, substrate types also influenced germination rates, with lower values in natural soil. The strongest effect on germination rates was by temperature, enhancing the difference in responses in substrate types. The low proportion of germinated seeds in soil (< 39 %), together with external local stress factors (e.g. grazing impact by herbivores), may be the critical factors contributing to the nearly total absence of seedlings and saplings of E. vargasii in the study area despite abundant seed production.

Efficiency of additives and internal physical chemical factors for pit latrine lifetime extension

Pit latrines are the most common form of on-site sanitation, but are blighted by the problem of pit fill-up. Little is known about what factors and conditions affect decomposition of pit content and thus govern pit filling, but the liquid–mass balance is the key factor. Under laboratory conditions the effect of inorganic and biological additives and the effect of physical chemical factors on solids hydrolysis of black water and human faeces were investigated to establish the potential of these to extend pit latrine lifetime. Additives did little or nothing to enhance net solids hydrolysis in batch tests or to reduce pit fill height in miniature simulated pit latrines. Physical chemical factors such as redox condition and initial pH increased solids hydrolysis, whereas temperature and substrate moisture did little. Since additives need contact with the substrate to act, measurements on faeces crust formation speed and strength were performed and showed that crusts formed within three hours and persisted af...

Reducing Substrate Moisture Content (SMC) during Greenhouse Production and Postproduction of Angelonia and Heliotrope Improves Crop Quality and Economic Value

Retail environments are rarely optimal for ornamental plants, and wilting caused by water stress is a major cause of postproduction shrinkage. The objective of this study was to determine the effect of two levels of substrate moisture content (SMC) applied during greenhouse production on angelonia (Angelonia angustifolia) ‘Angelface Blue’ and heliotrope (Heliotropium arborescens) ‘Simply Scentsational’ growth and physiological parameters and subsequent postproduction quality during simulated retail conditions. At the end of production, angelonia total plant shoot dry weight (DW) was reduced with 20% SMC compared with 40% SMC, and plants grown with 20% SMC had higher shoot coloring percentage, reduced internode length, and required less irrigation labor–related costs compared with 40% SMC. Heliotrope grown at 20% SMC produced the same size plant as 40% SMC, but had a higher shoot coloring percentage at the end of production and postproduction, indicating lower SMC resulted in higher visual quality compared with 40% SMC. For both species, 20% SMC increased plant visual quality compared with 40% SMC and reduced irrigation water input throughout production, resulting in reduced production costs and increased floral crop economic value.

The influence of a green roof drainage layer on retention capacity and leakage quality.

The aim of the research was to determine the influence of the substrate and different drainage materials on retention capacity and runoff water quality from three green roof containers. Phosphates were chosen as the water quality indicator based on their potential adverse impact on water quality in urban rainwater collectors. The field experiment was conducted at the Warsaw University of Life Sciences Water Center meteorological station in years 2013-2015. In terms of precipitation, the monitoring period covered a wet (+147.1 mm), average (+42.7 mm) and dry (- 66.3 mm) year. Leakage from the containers was recorded when the substrate moisture exceeded 20% and precipitation exceeded 3.5 mm/d for washed gravel, or 5.0 mm/d for a polypropylene mat and expanded clay. Phosphates were observed in leachates from all containers, with higher values observed in the second year of monitoring. As the result of this study, it can be concluded that the polypropylene mat and aggregates create different conditions for the formation of the leachate, in both volumes and its chemistry. The drainage layer made from a polypropylene mat is the most effective in terms of rainwater retention capacity and the resulting leachate quality.

Фитотоксичность почвосубстратов на основе шлаков металлургического производства, используемых в рекультивации

The aim of the study. To estimate the influence of various metallurgical slags on the initial stages of plant growth and development. The study location and time. Vegetation experiment was conducted in laboratory where during 2 weeks plants were grown on mixed soil-slag substrates under favourable air temperature and humidit, substrate moisture and illumination rate of 1500 lux. Methodology. To conduct phytotoxicity testing we followed the protocol described by the federal standard GOST R ISO 22030-2009, using one species of the monocotyledonous plants (oats Avena sativa L., cultivar “Rovesnik”) and one species of dicotyledonous plants (radish Raphanus sativus var. Sativus, cultivar “Saksa”). Four slags produced at the EVRAZ West Siberian plant by different technologies were used: white non-ferrous, blast furnace, converter and electrofurnace ones. The concentration of slags in soil-slag mixtures used as growth substrates, were 0 (soil);12.5; 25; 50 and 100% (pure slag). The data obtained were analyzed by descriptive statistics and correlation analysis. Main results. The growth and development of both radish and oats plants were not impeded by electrofurnace slag in all concentrations tested. The white non-ferrouswas found to be phytotoxic for both species in high concentrations only (50 and 100%). The converter and blast furnace slags had phytotoxic effect on radish only in their pure form, while for oats growth these slags were found to be harmful at 50% concentration. Conclusion. At the initial stages of plant growth and development three of the four studied metallurgical slags were found to have phytotoxic effect only in very concentrations in the substrates. Therefore to develop perspective technologies of slag use in recultivation we recommend to conduct longer vegetation and field experiments with lower slag concentrations for growing plants that can be really used for specific recultivation purpose, e.g. mixtures of legumes, grains and herbs, as well as woody bushes.

Thermal moderation of the intertidal zone by seaweed canopies in winter

Canopy-forming seaweeds are important foundation species or ecosystem engineers in intertidal habitats. By limiting a variety of abiotic stresses during low tides, algal canopies improve the performance of many understory organisms. The reduction of heat stress through substrate shading and moisture retention has received considerable attention in marine biology. However, the thermal influence of canopies during winter has not been empirically evaluated. Using intertidal fucoid canopies (Ascophyllum nodosum) from Atlantic Canada, we did a field experiment contrasting canopy-covered and no-canopy areas to test the hypothesis that canopies limit low temperatures during winter low tides. During 35 days between January and March, mid-intertidal temperature was often negative near the time of the lowest daily tides, on average more than 1 °C lower on bare substrate than under full canopy cover. The difference between both canopy treatments was higher around spring tides than around neap tides. Temperature on bare substrate was once even up to 10 °C lower than under a full canopy. Previous studies have shown that single occurrences of lethal negative temperatures and frequent occurrences of sublethal temperatures kill intertidal organisms every winter. Thus, our study suggests that, in addition to their bioprotective role during summer, canopy-forming seaweeds might also play a relevant facilitative role during winter.

Altitudinal patterns of myxomycete diversity across tropical forests of Southern Vietnam

In this paper, the fruit bodies of myxomycetes were collected in the field and were isolated from various substrates in humid chambers in the laboratory. The result showed that there is a high diversity of myxomycetes in the tropical forests of Vietnam. In totally, 159 species from 32 genera and 12 families developing on air and ground plant litter, rotten wood, feces of herbivorous animals, were identified with the 13 specially protected natural areas of Vietnam. In which, 69 taxa were firstly recorded in Vietnam. 4 new species were described. The result of the detailed comparative analysis using multivariate statistical methods was revealed some regularities of distribution of myxomycetes on a high-altitude gradient, biotopes, and also on various substrates. It is shown that: 1) the specieal diversity and abundance of myxomycetes are lower in mountain forests in comparison with plain forests, these indexes decrease inversely proportional to with altitude; 2) the abundance and specieal diversity of myxomycetes decrease by increasing the moisture of substrate; 3) There are differences in the species compositions between substrate groups of mountain forests and plain forests; 4) some common species in a temperate climate place have found in in the mountain tropical forests of Vietnam.

Precision Irrigation Scheduling Using ECH2O Moisture Sensors for Lettuce Cultivated in a Soilless Substrate Culture

Soilless culture has become an effective technique to avoid continuous cropping obstacles in protected horticulture. The reliable measurement of substrate moisture and a rational irrigation are difficult tasks because of the low water-holding capacity of the substrate. Our objectives were to study the irrigation scheduling based on the ECH2O moisture sensor(EC-5), using a matched model of wetting pattern and lettuce root zone in the substrate under drip irrigation. The EC-5 sensor was designed to connect to a controller, and a threshold value of 0.14 cm3/cm3 was set for irrigation scheduling. The controller turned on the irrigation system via communication with a solenoid valve on the irrigation line and with the EC-5 sensor in response to a threshold value and stopped when the overlap area of the wetting pattern and crop root zone was more than 90%. The EC-5 sensors were installed at a horizontal distance from each plant and depth of 3 and 4 cm, respectively, under the substrate surface to the check substrate moisture for lettuce cultivation, and at (3,15) cm or (6,15) cm to monitor leakage. These parameters were determined by simultaneously considering the distance from the plants, the depths of effective root water extraction, and the region of substrate wetted volume under drip irrigation. Leakage occurred during each irrigation process, but the leakage ratewas15.7% lower than that of conventional irrigation, as a result of irrigation scheduling in the presence of the EC-5 sensors.

Biochar increases plant growth and alters microbial communities via regulating the moisture and temperature of green roof substrates

Green roofs have increasingly been designed and applied to relieve environmental problems, such as water loss, air pollution as well as heat island effect. Substrate and vegetation are important components of green roofs providing ecosystem services and benefiting the urban development. Biochar made from sewage sludge could be potentially used as the substrate amendment for green roofs, however, the effects of biochar on substrate quality and plant performance in green roofs are still unclear. We evaluated the effects of adding sludge biochar (0, 5, 10, 15 and 20%, v/v) to natural soil planted with three types of plant species (ryegrass, Sedum lineare and cucumber) on soil properties, plant growth and microbial communities in both green roof and ground ecosystems. Our results showed that sludge biochar addition significantly increased substrate moisture, adjusted substrate temperature, altered microbial community structure and increased plant growth. The application rate of 10–15% sludge biochar on the green roof exerted the most significant effects on both microbial and plant biomass by 63.9–89.6% and 54.0–54.2% respectively. Path analysis showed that biochar addition had a strong effect on microbial biomass via changing the soil air-filled porosity, soil moisture and temperature, and promoted plant growth through the positive effects on microbial biomass. These results suggest that the applications of biochar at an appropriate rate can significantly alter plant growth and microbial community structure, and increase the ecological benefits of green roofs via exerting effects on the moisture, temperature and nutrients of roof substrates.

Leaf physiological and anatomical responses of Lantana and Ligustrum species under different water availability

Understanding the plant characteristics that support tolerance to water stress is important in choosing plants in arid or semi-arid environments, such as the Mediterranean. In particular, leaf characteristics can affect the response of plants to water stress. In order to understand how plants with different leaf features can overcome water stress, four water regimes were adopted on two species that are widespread in the Mediterranean environment, Lantana camara and Ligustrum lucidum. The four treatments were: control (C), in which the pot substrate moisture was maintained close to water container capacity (WCC), light deficit irrigation (LDI) irrigated at 75% of WCC, moderate deficit irrigation (MDI) at 50% of WCC, and severe deficit irrigation (SDI) at 25% of WCC. To better understand the action mechanisms, the trial was repeated twice (from January to May, and from May to September). Morphological, anatomical and physiological data were measured to identify the action mechanisms. Water deficit significantly decreased the biomass accumulation in both species during the experimental growth period. In Lantana, significant variations in total leaf area and leaf number were registered between C and SDI, while in Ligustrum, the differences were significant only for total leaf area. The water deficit treatments reduced the leaf thickness especially in Ligustrum. In both species, photosynthesis reduction was related to stomatal closure. Ligustrum showed a higher variability among treatments indicating a faster and more efficient response to water limitations compared to Lantana, as also demonstrated by the lower biomass reduction in the most severe water stress treatment.

Temperature correction of substrate moisture measurements made in coir in polytunnel-grown strawberries

The aim of this work is to assess the use of temperature corrected soil moisture data to improve the relationship between environmental drivers and the measurement of substrate moisture content in high porosity soil-free growing environments such as coir. Substrate moisture sensor data collected from strawberry plants grown in coir bags installed in a table-top system under a polytunnel illustrates the impact of temperature on capacitancebased moisture measurements. Substrate moisture measurements made in our coir arrangement possess the negative temperature coefficient of the permittivity of water where diurnal changes in moisture content oppose those of substrate temperature. The diurnal substrate temperature variation was seen to range from 7C to 25C resulting in a clearly observable temperature effect in substrate moisture content measurements during the 23 day test period. A temperature correction algorithm is presented in this work that has been derived from the Complex Refractive Index Model (CRIM) equation which was easily calibrated for coir and applied to the substrate moisture and temperature data. The diurnal variations seen with the temperature compensated substrate moisture data now align very well with the expected diurnal water demands of the strawberry plants. To further evaluate the relationship between environmental drivers of solar radiation and vapour pressure deficit with substrate moisture the temperature correction algorithm was programmed within a GP2 data logger. The GP2 was also collecting solar radiation, air temperature and relative humidity data. The resulting comparison of substrate moisture responses to environmental drivers illustrates a significantly improved correlation with temperature corrected substrate moisture measurements. We conclude that this new temperature correction algorithm addresses the effect of temperature on the relative permittivity of water which will affect all capacitance based sensor measurements in high porosity soil-free growing substrates such as coir.

A novel dielectric tensiometer enabling precision irrigation control of polytunnel-grown strawberries in coir

The benefits of closed-loop irrigation control have been demonstrated in grower trials, which show the potential for improved crop yields and resource usage. Managing water use, by controlling irrigation in response to soil or substrate moisture changes, to meet crop water demands is a popular approach but requires substrate specific moisture sensor calibrations and knowledge of the moisture levels that result in water deficit stress or over-watering. The use of water tension sensors removes the need for substrate specific calibration and enables a more direct relationship with hydraulic conductivity. In this paper, we present a novel dielectric tensiometer that has been designed specifically for use in soil-free substrates such as coir, peat and rockwool with a water tension measurement range of -0.7 to -2.5 kPa. This new sensor design has also been integrated with a precision PID-based (drip) irrigation controller in a small scale coir substrate strawberry growing trial: 32 strawberry plants in 4 coir growbags under a polytunnel. The data illustrate that excellent regulation of water tension in coir can be achieved, which delivers robust and precise irrigation control - matching water delivery to the demands of the plants. During a 30-d growing period, vapour pressure deficit (VPD) and daily water use data were collected and the irrigation controller set to maintain coir water tension at the following levels: -0.90, -0.95 and -1 kPa for at least 7 consecutive days at each level. For each set-point, the coir water tension was maintained by the irrigation controller to within ±0.05 kPa. Meanwhile, the polytunnel VPD varied diurnally from 0 to maximum of 5 kPa over the trial period. Furthermore, the combination of the dielectric tensiometer and the method of PID-based irrigation control resulted in a linear relationship between average daily VPD and daily water use over 9 d during the cropping period.

Aesthetic Quality and Strength of Bioplastic Biocontainers at Different Substrate Volumetric Water Contents

Various types of emerging bioplastic containers present a range of physical and chemical properties and can perform differently from one another in production environments. Container performance may be affected by substrate moisture content. We quantified the effects of bioplastic container type and substrate volumetric water content (VWC) on the aesthetic and mechanical strength properties of bioplastic containers and on plant growth. Seedlings of ‘Divine Cherry Red’ new guinea impatiens (Impatiens hawkeri W. Bull) and ‘Pinot Premium Deep Red’ zonal geranium (Pelargonium ×hortorum L.H. Bailey) were transplanted into five types of 11.4-cm–diameter containers, four types made from bioplastics and one type made from petroleum-based plastic and used as a control. Plants were watered to container capacity at transplant, allowed to dry down to VWC thresholds of 0.20 or 0.40 m3·m−3, and subsequently maintained at desired set points by using a precision irrigation system controlled by soil moisture sensors. Total volume of water applied per plant to new guinea impatiens was affected by VWC and not container type, whereas irrigation volume was affected by both for geranium. Growth index and shoot dry mass (SDM) of new guinea impatiens and geranium were affected by VWC. Container type affected growth index and SDM of geranium only. Water use efficiency (WUE) of both species was similar regardless of container type and VWC. Aesthetic quality varied based on VWC for only one container type, which was made from a blend that included soy-based bioplastic. Containers manufactured with polyhydroxyalkanoates (PHA) and dried distiller’s grains and solubles (DDGS) or polylactic acid (PLA), soy polymer with adipic anhydride (SP.A), and a proprietary bio-based filler (BR) derived from modified DDGS were stronger when maintained at a lower VWC, 0.20 m3·m−3. Our findings indicate that restricting irrigation to the minimum needed to achieve the desired crop growth is a viable strategy for sustaining aesthetic quality and strength of bioplastic containers manufactured with plant protein–based fillers such as SP.A and BR. Other bioplastic containers, such as those made of PLA–lignin biocomposite, show durability equal to that of petroleum-based plastic containers and maintain pristine appearance regardless of substrate VWC during production.

Physiology and quality of Eugenia dysenterica DC seedlings grown in vermiculite and rice husk-based substrates

Abstract Eugenia dysenterica DC is a fruiting species endemic to the Brazilian Cerrado, belonging to the Myrtaceae family and popularly known as Cagaiteira. It has medicinal and antifungal properties, and has an important function in the ecosystem. Nevertheless, there are few studies about the maintenance of this species. The aim of this study was to evaluate the growth, nutrition, quality and physiology of E. dysenterica seedlings grown in fine vermiculite and rice husk-based substrates in the following combinations: 1:0, 3:1, 1:1, and 1:3, in addition to Trimix® commercial substrate and vermiculite only. The physical attributes of substrates (dry and moist densities, available water, remaining water, aeration space and total porosity), seedling emergence percentage, emergence speed index, gas exchange, chlorophyll a fluorescence, relative seedling water content, relative substrate moisture content, plant biometric growth characteristics, accumulated dry weight and nutritional status were evaluated through leaf macronutrient content 128 days after emergence. The increase in the proportion of rice husk mixed with vermiculite resulted in reduction of the dry and moist densities of substrates, available water, remaining water, total porosity and moisture content, and increased the aeration space in substrates. The fine vermiculite substrate promoted the highest Dickson’s quality index and the greatest stem diameter of plants. Seedlings grown on vermiculite substrate presented higher N and K content in leaves, and those grown in Trimix® substrate showed higher leaf Mg content. Substrates did not alter the physiological attributes of seedlings.

Arbuscular Mycorrhiza Improves Substrate Hydraulic Conductivity in the Plant Available Moisture Range Under Root Growth Exclusion.

Arbuscular mycorrhizal fungi (AMF) proliferate in soils and are known to affect soil structure. Although their contribution to structure is extensively investigated, the consequences of those processes for soil water extractability and transport has, so far, gained surprisingly little attention. Therefore we asked, whether AMF can affect water retention and unsaturated hydraulic conductivity under exclusion of root ingrowth, in order to minimize plant driven effects. We carried out experiments with tomato inoculated with Rhizoglomus irregulare in a soil substrate with sand and vermiculite that created variation in colonization by mixed pots with wild type (WT) plants and mycorrhiza resistant (RMC) mutants. Sampling cores were introduced and used to assess substrate moisture retention dynamics and modeling of substrate water retention and hydraulic conductivity. AMF reduced the saturated water content and total porosity, but maintained air filled porosity in soil spheres that excluded root ingrowth. The water content between field capacity and the permanent wilting point (6–1500 kPa) was only reduced in mycorrhizal substrates that contained at least one RMC mutant. Plant available water contents correlated positively with soil protein contents. Soil protein contents were highest in pots that possessed the strongest hyphal colonization, but not significantly affected. Substrate conductivity increased up to 50% in colonized substrates in the physiologically important water potential range between 6 and 10 kPa. The improvements in hydraulic conductivity are restricted to substrates where at least one WT plant was available for the fungus, indicating a necessity of a functional symbiosis for this effect. We conclude that functional mycorrhiza alleviates the resistance to water movement through the substrate in substrate areas outside of the root zone.

Container volume and subirrigation schedule influence Quercus variabilis seedling growth and nutrient status in the nursery and field

ABSTRACTContainer volume and irrigation management affect seedling growth in the nursery and field. We evaluated the effects of container volumes (D40, 656 ml; D60, 983 ml) and subirrigation schedules (85%, 75%, 65%, and 55% of 100% total substrate moisture content, TSMC) on seedling growth in a greenhouse and outplanting performance of Chinese cork oak (Quercus variabilis Blume) for one growing season. In the greenhouse, morphological attributes of seedlings grown at 85% and 75% TSMC in D60 were greater than those grown at 65% and 55% TSMC in D40. After outplanting, seedlings grown at 75% TSMC in D60 were tallest but not different than those grown at 65% TSMC. Shoot (9.2 g), root (28.0 g), and total (37.2 g) biomass of seedlings subirrigated at 55% TSMC in D60 reached maximum values, but shoot biomass for seedlings grown at either 65% or 55% TSMC was similar. Root and total N and K contents of seedlings subirrigated at 65% and 55% TSMC were greater than those grown at 85% and 75% TSMC. Our results suggest that reducing the subirrigation schedule threshold and using a container with more volume could improve oak seedling growth and nutrient accumulation during the first growing season of outplanting.

Arbuscular Mycorrhiza Alleviates Restrictions to Substrate Water Flow and Delays Transpiration Limitation to Stronger Drought in Tomato.

Arbuscular mycorrhizal fungi (AMF) proliferate in soil pores, on the surface of soil particles and affect soil structure. Although modifications in substrate moisture retention depend on structure and could influence plant water extraction, mycorrhizal impacts on water retention and hydraulic conductivity were rarely quantified. Hence, we asked whether inoculation with AMF affects substrate water retention, water transport properties and at which drought intensity those factors become limiting for plant transpiration. Solanum lycopersicum plants were set up in the glasshouse, inoculated or not with Funneliformis mosseae, and grown for 35 days under ample water supply. After mycorrhizal establishment, we harvested three sets of plants, one before (36 days after inoculation) and the second (day 42) and third (day 47) within a sequential drying episode. Sampling cores were introduced into pots before planting. After harvest, moisture retention and substrate conductivity properties were assessed and water retention and hydraulic conductivity models were fitted. A root water uptake model was adopted in order to identify the critical substrate moisture that induces soil derived transpiration limitation. Neither substrate porosity nor saturated water contents were affected by inoculation, but both declined after substrates dried. Drying also caused a decline in pot water capacity and hydraulic conductivity. Plant available water contents under wet (pF 1.8–4.2) and dry (pF 2.5–4.2) conditions increased in mycorrhizal substrates and were conserved after drying. Substrate hydraulic conductivity was higher in mycorrhizal pots before and during drought exposure. After withholding water from pots, higher substrate drying rates and lower substrate water potentials were found in mycorrhizal substrates. Mycorrhiza neither affected leaf area nor root weight or length. Consistently with higher substrate drying rates, AMF restored the plant hydraulic status, and increased plant transpiration when soil moisture declined. The water potential at the root surface and the resistance to water flow in the rhizosphere were restored in mycorrhizal pots although the bulk substrate dried more. Finally, substrates colonized by AMF can be more desiccated before substrate water flux quantitatively limits transpiration. This is most pronounced under high transpiration demands and complies with a difference of over 1,000 hPa in substrate water potential.

Using a Hydrological Model to Simulate the Performance and Estimate the Runoff Coefficient of Green Roofs in Semiarid Climates

Green roofs offer a series of benefits to buildings and to the urban environment. Their use in dry climates requires optimizing the choice of their components (i.e., vegetation, substrate and drainage layer) for the specific local climatic conditions, in order to minimize irrigations needs while preserving the attributes of the roof. In this study, we calibrated and validated an existing hydrological model—IHMORS—for the simulation of the hydrological performance of green roofs. Simulated results were compared to experimental data obtained in an outdoor test facility on several green roof specimens, representing a variety of green roofs configurations. IHMORS was able to reasonably predict the soil moisture dynamics for all tested specimens. The specimens of 10 cm depth were the best simulated by the model, while some overestimation was observed during the model validation for the 5 and 20 cm depth specimens. The model was then used to estimate the number of days in which irrigation is needed, as well as analyze the water runoff control performance of all specimens. We related the amount of water retained by the substrate and depth, magnitude and intensity of precipitation event, and the initial substrate moisture. For all events, the lowest runoff coefficient was simulated for the 20 cm specimens. Our study showed the full potential of the model for estimating the water needs and the runoff control performances of different variants of green roofs.

New cost-effective bioconversion process of palm kernel cake into bioinsecticides based on Beauveria bassiana and Isaria javanica.

The present study aimed to add value to palm oil by-products as substrates to efficiently produce conidia of Beauveria bassiana and Isaria javanica (Hypocreales: Cordycipitaceae) for biological control of the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae), through a solid-state fermentation process using palm kernel cake and palm fiber as nutrient source and solid matrix, respectively. The optimum culture conditions yielded high concentrations of viable conidia after air-drying, when the fungi were grown on palm kernel cake (B. bassiana 7.65 × 109 and I. javanica 2.91 × 109conidiag-1 dry substrate) after 6days under optimal growth conditions set to 60% substrate moisture and 32°C. Both fungal strains exhibited high efficacy against third-instar whitefly nymphs, inducing mortality up to 62.9 and 56.6% by B. bassiana and I. javanica, respectively, assessed after 9days post-application in a screenhouse. Furthermore, we noted that insect mortality was strongly correlated with high atmospheric moisture, while B. bassiana appeared to require shorter accumulative hours under high moisture to kill whitefly nymphs compared to I. javanica. Our results underpin a feasible and cost-effective mass production method for aerial conidia, using palm kernel as the main substrate in order to produce efficacious fungal bioinsecticides against an invasive whitefly species in Brazil. Finally, our fermentation process may offer a sustainable and cost-effective means to produce eco-friendly mycoinsecticides, using an abundant agro-industrial by-product from Brazil that will ultimately assist in the integrated management of agricultural insect pests.

Αcidogenic fermentation of wheat straw after chemical and microbial pretreatment for biofuel applications

The anaerobic acidogenic fermentation of wheat straw was studied, after various chemical and microbial pretreatments, namely (a) chemical delignification, (b) hydrolytic pretreatment with T. viride of the chemically delignified straw to enhance the organic acid (OAs) yields in the subsequent acidogenic fermentations, and (c) microbial delignification by P. chrysosporium to enhance the biodegradability of the cellulosic material and avoid the chemical pretreatment. The subsequent anaerobic acidogenesis experiments of the wheat straw samples were carried out using a UASB culture free and immobilised on γ-alumina. Hydrolysis with T. viride was limited and slightly improved the result of the acidogenesis. On the other hand, delignification by P. chrysosporium produced satisfactory results, comparable to those of the chemical delignification process. The optimum substrate moisture content for the microbial delignification was 85%. In all cases the immobilised cells increased the OAs yields during the acidogenic fermentations by about 2-fold. Lactic, acetic and butyric acid were the prevailing OAs produced. The OAs could be then used as structural components of ester-based biofuels similar to biodiesel, an approach that has been recently proposed as a cost-effective and environmentally friendly alternative for 2nd generation biofuels production.