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Under the impression of changing rainfall patterns, agriculture in Germany faces increasing drought stress problems and water saving irrigation is gaining importance in the agricultural practice. Porous pipes for subsurface irrigation are an innovative method which is promoted as a water-efficient way to apply irrigation water. In the present study “Ecotubes” porous pipe irrigation was used for irrigation of “Lollo Bionda” lettuce at the University of Weihenstephan-Triesdorf in Southern Germany and compared to state-of-the art drip irrigation both at surface and sub-surface installation. Four treatments were compared during three experimental cycles “summer”, “late summer” and “autumn”: (a) drip irrigation in standard surface installation (control), (b) sub-surface drip irrigation, (c) porous pipes at standard operation and (d) porous pipes at very low pressure. The treatments were compared in terms of crop development, irrigation water applied, yield and water use efficiency (WUE). The highest yields were observed at low pressure irrigation with porous pipes (39.4 t/ha) followed by subsurface drip irrigation (36 t/ha). However, it was shown that the total amount of irrigation water applied, rather than the irrigation method determined the overall yield level. Subsurface irrigation methods had the highest WUE with 50.5 and 49.6 kg/m3 for porous pipes and subsurface drip irrigation, respectively. The study shows that subsurface micro irrigation systems are good for water saving horticultural production in Germany. The use of porous pipes is a good option for subsurface irrigation depending on the technological development in terms of installation and recovery, and the durability of the material.

Cascade hydroponics, that is, the application of the circular economy concept in greenhouse hydroponic crops, may be considered as an alternative means to increase water and nutrient use efficiency in greenhouses. In such systems, the drained nutrient solution from a crop may be used as input in a second crop. However, the second (secondary) crop in the loop must be a crop that is less sensitive to salinity than the first (primary) crop. In the present study, the salinity tolerance of basil plants grown in rockwool and nutrient film technique (NFT) systems was investigated in order to study the potential of using a basil crop as a secondary crop in a cascade hydroponic system. In total, 4 electrical conductivity (EC) levels of the irrigation nutrient solution were tested (2, 4, 6, and 8 dS m−1), and salinity was imposed by NaCl or by macronutrients. Plant growth varied across the different substrates, with those grown in the NFT system being less affected as opposed to the rockwool-grown basil plants, which showed a significant growth decrease with EC values higher than 4 dS m−1. This relatively low growth pattern was associated with a decrease in water use efficiency (WUE) in the rockwool system. On the contrary, in the NFT system, the continuous flow of the nutrient solution in the root zone of the plants contributed to the alleviation of negative salinity effects, yielding up to 30 kg FM m−2 WUE even for the plants irrigated with the highest salinity treatment (8 dS m−1). The majority of macro- and micronutrients in the leaf tissue of basil were positively affected by the higher levels of conductivity in the nutrient solution. Therefore, basil cultivation could be efficiently incorporated as a secondary crop in a cascade NFT cropping system. This would contribute to drainage management in hydroponics, as the crop could be irrigated through the moderately saline drainage from a primary crop due to either NaCl or high nutrient accumulation in the leachates.

In a cascade hydroponic system, the used nutrient solution drained from a primary crop is directed to a secondary crop, enhancing resource-use efficiency while minimizing waste. Nevertheless, the inevitably increased EC of the drainage solution requires salinity-tolerant crops. The present study explored the salinity-tolerance thresholds of basil to evaluate its potential use as a secondary crop in a cascade system. Two distinct but complemented approaches were used, the first experiment examined basil response to increased levels of salinity (5, 10 and 15 dS m−1, compared with 2 dS m−1 of control) to identify the limits, and the second experiment employed a cascade system with cucumber as a primary crop to monitor basil responses to the drainage solution of 3.2 dS m−1. Growth, ascorbate content, nutrient concentration, and total amino acid concentration and profile were determined in both experiments. Various aspects of basil growth and biochemical performance collectively indicated the 5 dS m−1 salinity level as the upper limit/threshold of tolerance to stress. Higher salinity levels considerably suppressed fresh weight production, though the total concentration of amino acids showed a sevenfold increase under 15 dS m−1 and 4.5-fold under 5 and 10 dS m−1 compared to the control. The performance of basil in the cascade system was subject to a compromise between a reduction of fresh produce and an increase of total amino acids and ascorbate content. This outcome indicated that basil performed well under the conditions and the system employed in the present study, and might be a good candidate for use as a secondary crop in cascade-hydroponics systems.

We present a novel analysis of gas damping in capacitive MEMS transducers that is based on a simple analytical model, assisted by Monte-Carlo simulations performed in Molflow+ to obtain an estimate for the geometry dependent gas diffusion time. This combination provides results with minimal computational expense and through freely available software, as well as insight into how the gas damping depends on the transducer geometry in the molecular flow regime. The results can be used to predict damping for arbitrary gas mixtures. The analysis was verified by experimental results for both air and helium atmospheres and matches these data to within 15% over a wide range of pressures.

The circular economy in agriculture aims to reduce waste while also making best use of residues by using economically viable processes and procedures to increase their value. In this study a two-level cascade cultivation system was set up under greenhouse conditions. The research was focused on the identification of crop species as secondary crops and the development/iterative optimization of cultivation practices. For this purpose, different crop-combinations with a primary and different secondary crops were investigated using different system-layouts. Measurements were carried out during two cultivation periods. During the 1st Period a combination of cucumber (Cucumis sativus) as primary crop, with rosemary (Rosmarinus officinalis), basil (Ocimum basilicum), and peppermint (Mentha piperita) as secondary crops, was evaluated. In the 2nd Period the drainage of tomato (Solanum lycopersicum) plants was re-used to irrigate spearmint (Mentha spicata), dill (Anethum graveolens), celery (Apium graveolens) and parsley (Petroselinum crispum) plants. In both periods, different fertigation management strategies based on the drainage solution of the primary crop were employed. The use of the cascade hydroponic system improved both crop water and nutrient use efficiency. Notably, the NO3 disposal was about 40% less as compared to a monoculture. Average fresh water consumption of secondary crop plants irrigated with diluted drainage solution was reduced by 30% in comparison to plants irrigated with fresh water.

Purple carrots are rich in anthocyanins which are interesting as natural dyes in food and beverages. It is, thus, relevant to increase the concentration of anthocyanins by agricultural practices. We tested whether the combination of reduced nitrogen (N) supply and extended harvesting periods maximized the anthocyanin concentration of purple carrot roots, ideally without reducing their yield. The carrot variety ‘Deep Purple’ was grown with total N supplies of 220 kg N ha−1 (controls) and 73 kg N ha−1 (reduced N), respectively. Upon harvests in September, October and November, root yield and quality were assessed. Concentrations of chlorophylls (leaves) and anthocyanins (roots and leaves) were determined by spectroscopic and chemical analyses, and carbon and N content were quantified. Reduced N supply neither affected leaf or root biomass nor their chemical composition. Later harvests did not impact the yield of roots, but increased their diameter by 8.5–20%. Additionally, the anthocyanin concentrations of the roots increased by 40–50% in the controls, but not in N-limited plants, at late harvests. Consequently, extending the harvesting period might increase the anthocyanin concentration in roots of ‘Deep Purple’. Moreover, N supply might be reduced for this carrot variety without negative effects on root yield.

1. Plant species that arrive first in the system can affect assembly (priority effects). However, effects of order of arrival of different plant functional groups (PFGs) on root development have not yet been investigated under field conditions. 2. We measured standing and fine root length density in the first and third year of a grassland field experiment. We wanted to know if manipulating PFG order of arrival would affect root development, and if priority effects are modulated by soil type. 3. Sowing legumes first created a priority effect that was found in the first and third year, with a lower standing root length density in this treatment, even though the plant community composition was different in each of the studied years. Fine root length density was not affected by order of arrival, but changed according to the soil type.4. Synthesis. We found strong evidence that sowing legumes first created a priority effect below-ground that was found in the first and third year of this field experiment, even though the functional group dominance was different in each of the studied years.

First constructed two and a half centuries ago, the hydraulic ram is one of the oldest mechanical devices for water lifting. The first application utilised the principle for the water supply of a brewery. In this set up a water valve had to be manually closed. Very soon upgrades for an automatic operation of the device were adapted. With technological progress also the ram was improved, but got superseded by electric and fuel powered pumps. Today the ram constitutes a reliable and low-maintenance, sustainable alternative to motor-driven pumps. The hydraulic ram uses the kinetic energy of water flowing in a driver pipe to pump up about 10% of it to a higher elevation. Thereby, no external energy input is needed. As a lot of studies had been carried out constructing hydraulic rams with self built valves and for high water supply, the aim of this investigation was to construct a reliable and low-cost ram, made of locally available off-the-shelf parts. Different valves were tested in the lab under varying elevations of the water column in the driver pipe. The pumping pressure and water flow in the supply pipe were recorded for determining the ram's efficiency. An off-the-shelf clap check valve proved mosrt reliable with an acceptable efficiency of over 30%. One unit of a hydraulic ram was installed at a foothill location at Ban Ha, Samoeng District, Chiang Mai Province, and connected to an automatic low pressure irrigation system to irrigate a small plot of coffee trees. Soil moisture was monitored. The hydraulic ram operated maintenance free and fully automatic over six weeks, supplying the field sufficient quantities of water during this period at a pumping efficiency of 44%.

A combination of anti-reflection coated glass and ethylene tetrafluoroethylene film is introduced as a novel glazing system for greenhouses and similar buildings. It combines the advantages of the individual materials (durability/low weight; favourable condensation behaviour/self-cleaning) and of single and double layer systems (light transmission/insulation). By inflating/deflating the glass–film interspace, the additional insulation can be switched on and off. Since no standard method for this purpose is available, a hot box-system was developed to measure heat transfer coefficients ( U -values) of different models of the glass–film-combination (GFC) and other commonly used greenhouse glazing materials at different surface inclinations; with or without condensation. Surface inclination did not greatly influence heat transfer. Condensation increased the U -values more pronounced for single layer-systems than for the GFC. Influences of wind velocity on heat transfer decreased with the degree of insulation. Overall, when mounted with adhesive tape, the energy efficiency of the GFC was 38% higher compared to customary float glass. The energy saving potential of plastic profile mounted GFC versions was 50% and 64% for the double and triple layer system (ETFE-film on both sides of the glass pane), respectively. PAR transmission of the GFC was similar to single pane float glass, its UV transmittance markedly higher.

Black leaf mold caused by Pseudocercospora fuligena is an important fungal disease of tomato in Southeast Asia. The objective of this study was to evaluate the control of this disease using high manganese (Mn) applied to the root substrate and to evaluate the role of the leaf apoplast in plant response to fungal infection. In a nethouse experiment in Thailand, Mn above the optimum for plant growth but below toxicity increased resistance of tomato plants to black leaf mold. Enhanced resistance caused by Mn was also obtained when tomato plants were grown under controlled conditions in a mist chamber and artificially inoculated with the fungus. Manganese significantly increased plant peroxidases in the leaf apoplast. The highest peroxidase activity was measured when plants were inoculated with Pseudocercospora fuligena. Defense-related proteins in the leaf apoplast increased when plants were inoculated with Pseudocercospora fuligena but not when treated with high Mn. It is concluded that Mn above the optimum level for plant growth can contribute to the control of Pseudocercospora fuligena in tomato. The Mn effect on disease resistance is associated with the activation of plant peroxidases in the leaf apoplast. A systemic response, possibly mediated by NADH peroxidase activity, also seems to trigger disease resistance in leaves with low Mn concentrations.

A tomato (Solanum lycopersicum L.) crop was grown in four greenhouses during the dry season 2005/06 in Central Thailand. Sidewalls and roof vents of two greenhouses were covered with nets and these greenhouses were mechanically ventilated when air temperature exceeded 30 °C (NET). The other two greenhouses were covered with polyethylene film and equipped with a fan and pad cooling system (EVAP). Overall mean air temperature was significantly reduced by 2.6 and 3.2 °C (day) and 1.2 and 2.3 °C (night) in EVAP as compared to NET and outside air, respectively. Temperature maxima in EVAP averaged about 4 °C lower than in NET and outside. The relative humidity was around 20 and 30% (day) and 10 and 15% (night) higher in EVAP than in NET or outside, respectively. Vapour pressure deficit averaged 0.25 kPa in EVAP, 1.03 kPa in NET and 1.48 kPa outside. The crop water-consumption was significantly lower in EVAP (1.2) than in NET (1.8 L plant−1 day−1), which is ascribed to reduced transpiration in EVAP. Total fruit yield was similar in NET (6.4 kg plant−1) and EVAP (6.3 kg plant−1). The quantity of undersized (mostly parthenocarpic) and blossom-end rot (BER)-affected fruits was reduced in EVAP. However, the proportion of marketable yield was significantly higher in NET (4.5 kg plant−1) than in EVAP (3.8 kg plant−1), owing largely to an increased incidence of fruit cracking (FC) in EVAP. Higher FC but lower BER incidence coincided with higher fresh weight and Ca concentration in the fruits in EVAP. It is concluded that in regions with high atmospheric relative humidity evaporative cooling without technical modifications allowing dehumidification will not improve protected tomato production.

Studies were conducted in tropical greenhouses to elucidate the role of UV light (UV) for the orientation and flight behavior of the thrips Ceratothripoides claratris (Shumsher) (Thysanoptera: Thripidae), an important pest on tomato (Lycopersicum spp.), in the hot and humid tropics of South-East Asia. Four greenhouse types characterized by different combinations of UV-absorbing or -transmitting plastic films and nets on the roof and sidewalls, respectively, were used in these studies. In choice experiments C. claratris always preferred the environment with higher UV intensity. Furthermore, natural thrips populations around the greenhouses were captured during the majority of control dates in lower numbers on sticky traps on the outer sidewalls of greenhouses clad with UV-absorbing materials compared with UV-transmitting materials. The immigration of thrips into the UV-absorbing greenhouses also was impeded, as measured by sticky traps on the inner side walls. UV-absorbing plastic roofs showed the most pronounced deterrent effect for thrips movement toward greenhouses, and the UV-absorbing net effectively reduced thrips numbers crossing the net barrier into the greenhouse. A simple extension of UV-absorbing plastic roof around conventional greenhouses clad with UV-transmitting plastic and net reduced thrips capture rates inside the greenhouse up to 77% when thrips was released at 1 m distance from the net walls. These results are discussed in the context of wavelength dependent insect vision and the dilemma of tropical greenhouse constructions, i.e., physical pest exclusion versus appropriate ventilation to ensure a conducive microclimate for plant growth.

Two tomato (Lycopersicon esculentum Mill.) cultivars King Kong 2 (KK2) and FMTT 260 (FMTT) were grown in a net-covered greenhouse in Central Thailand to investigate the influence of fruit applications of combined aqueous calcium (Ca) and boron (B) solutions amended or not with the tenside Glucopon® on fruit yield and quality. Special attention was paid on blossom-end rot (BER) and fruit cracking (FC), two prevailing disorders in tomato and main causes for non-marketability of tomato fruits under the conditions of protected cultivation in Central Thailand. While no effect of the additional Ca and B applications on total fruit yield was observed, the composition of the non-marketable fraction of fruit yield differed significantly between treatments and cultivars. Cultivar KK2 proved to be highly susceptible to both BER and FC and, therefore, produced less marketable fruits than cv. FMTT. The Ca and B sprays decreased the incidence of BER but increased FC at the same time. Addition of the tenside Glucopon® to the Ca and B solutions did not yield any further advantage. The contrasting effect of the Ca and B sprays on BER and FC resulted in similar levels of non-marketable fruit yield in the treatments with or without the sprays for both cultivars. The nutrient status in different fruit segments was surveyed during fruit development. The Ca concentration in the distal end of the fruit during the time of rapid fruit growth was correlated with the BER incidence in mature fruits. Since additional Ca and B sprays are labor-intensive and did not significantly reduce the portion of non-marketable fruits, the selection of cultivars insusceptible to BER and FC appears to be of highest priority when conditions favoring these disorders are to be expected. This is particularly true for protected cultivation in Central Thailand.

Fundamental knowledge of the molecular mechanisms underlying virus transmission by arthropods is a prerequisite for the creation of new strategies to modulate vector competence. There have been several recent advances in identifying the viral and vector determinants involved in virus recognition, attachment and retention.

We here describe the structural requirements for Golgi localization and a sequential, localization-dependent activation process of protein kinase C (PKC) involving auto- and transphosphorylation. The structural basis for Golgi compartment localization was analyzed by confocal microscopy of HeLa cells expressing various PKC-green fluorescent protein fusion proteins costained with the Golgi compartment-specific markers p24 and p230. Deletions of either the NH2-terminal hydrophobic or the cysteine region, but not of the pleckstrin homology or the acidic domain, of PKC completely abrogated Golgi localization of PKC. As an NH2-terminal PKC fragment was colocalized with p24, this region of PKC is essential and sufficient to mediate association with Golgi membranes. Fluorescence recovery after photobleaching studies confirmed the constitutive, rapid recruitment of cytosolic PKC to, and stable association with, the Golgi compartment independent of activation loop phosphorylatio n. Kinase activity is not required for Golgi complex targeting, as evident from microscopical and cell fractionation studies with kinase-dead PKC found to be exclusively located at intracellular membranes. We propose a sequential activation process of PKC, in which Golgi compartment recruitment precedes and is essential for activation loop phoshorylation (serines 738/742) by a transacting kinase, followed by auto- and transphosphorylation of NH2-terminal serine(s) in the regulatory domain. PKC activation loop phosphorylation is indispensable for substrate phosphorylation and thus PKC function at the Golgi compartment.

Rhizodeposition is considered to be an important source for soil organic carbon. Increased root turnover rates may be a mechanism employed by plants to respond to nutrient limiting conditions. Estimation of rhizodeposition for field-grown oilseed-rape plants (Brassica napus L.) using 14C-pulse labelling technique was the objective of our present work. Treatments consisted of two soil tillage systems (ploughing/surface tillage, ‘Horsch’) and two N rates (0 and 240 kg N/ha). Soil, roots, and shoot were sampled three weeks after labelling and also at the end of the growing season. Rhizodepostion was calculated from the decrease in 14C activity between the sampling dates. Under high N supply retranslocation of assimilates, an increase of root 14C-content which is incompatible with our methodical approach was observed. Therefore, a second experiment was conducted, combining pulse-labelling and ingrowth-core techniques to calculate the transfer of mobile 14C-labelled assimilates to newly formed roots. It is concluded that rhizodeposition accounted for up to 90% of total carbon allocation to the roots (high N supply and ploughing). N supply and soil tillage had pronounced effects on 14C partitioning within the shoot and also high N supply as well as ploughing resulted in reduced 14C allocation to generative organs.

Knowledge of the molecular mechanisms underlying virus transmission is a prerequisite to the creation of new approaches to modulate vector competence and to reduce the multiplication of initial infection sites in seed and pollen. In this chapter the recent advances made in identifying the virus, vector and host determinants involved in transmission processes are described.

A GroEL homolog with a molecular mass of 60 kDa, produced by the primary endosymbiotic bacterium (a Buchnera sp.) of Myzus persicae and released into the hemolymph, has previously been shown to be a key protein in the transmission of potato leafroll virus (PLRV). Like other luteoviruses and pea enation mosaic virus, PLRV readily binds to extracellular Buchnera GroEL, and in vivo interference in this interaction coincides with reduced capsid integrity and loss of infectivity. To gain more knowledge of the nature of the association between PLRV and Buchnera GroEL, the groE operon of the primary endosymbiont of M. persicae (MpB groE ) and its flanking sequences were characterized and the PLRV-binding domain of Buchnera GroEL was identified by deletion mutant analysis. MpB GroEL has extensive sequence similarity (92%) with Escherichia coli GroEL and other members of the chaperonin-60 family. The genomic organization of the Buchnera groE operon is similar to that of the groE operon of E. coli except that a constitutive promoter sequence could not be identified; only the heat shock promoter was present. By a virus overlay assay of protein blots, it was shown that purified PLRV bound as efficiently to recombinant MpB GroEL (expressed in E. coli ) as it did to wild-type MpB GroEL. Mutational analysis of the gene encoding MpB GroEL revealed that the PLRV-binding site was located in the so-called equatorial domain and not in the apical domain which is generally involved in polypeptide binding and folding. Buchnera GroEL mutants lacking the entire equatorial domain or parts of it lost the ability to bind PLRV. The equatorial domain is made up of two regions at the N and C termini that are not contiguous in the amino acid sequence but are in spatial proximity after folding of the GroEL polypeptide. Both the N- and C-terminal regions of the equatorial domain were implicated in virus binding.