Growth Greenhouse Research Articles

Performance of Direct Evaporative Cooling System under Egyptian Conditions

The main objective of this research is to optimize the parameters affecting the performance of the direct evaporative cooling system, to achieve that, a mathematical model of heat and mass balance of the evaporative cooling pads was developed to predict most important factors affecting the performance of the system. The model was able to predict the temperature, humidity ratio, wet bulb effectiveness, dew point effectiveness and temperaturehumidity index of outlet air at different ambient air temperatures (25, 30, 35 and 40°C), different inlet air velocities (1.5, 3, 4.5 and 6 m s-1), ambient air humidities (0.01, 0.02, 0.03 and 0.04 kg kg-1) and different lengths of pad (0.5, 1.0, 1.5 and 2.0 m). The results showed that the outlet temperature increases with increasing ambient temperature, inlet air velocity, ambient air humidities and lengths of pad. The results also showed that the wet bulb effectiveness ranged from 0.927 to 1.086. The dew point effectiveness ranged from 0.561 to 0.747. The humidity ratio ranged from 0.027 to 0.035 kg kg-1. The temperature-humidity index ranged from 21.15 to 33.56°C on study treatments. The predicted outlet temperatures were in a reasonable agreement with those measured, where, it ranged 17.027 to 29.978°C theoretically while it was from 19.605 to 30.748°C experimentally. The prediction of temperature determines the optimum condition of plant growth in greenhouse, so that the model helps this optimization.

BIOLOGICAL ACTIVITY OF DIFFERENT BOTANICAL EXTRACTS AS EVALUATED BY MEANS OF AN ARRAY OF IN VITRO AND IN VIVO BIOASSAYS

Recently, increasing interest has been paid to the biostimulant properties of plant extracts as they have been shown to improve crop yield and quality. Biolchim SpA is a leading company in the production and commercialization of biostimulants. The working approach to the development of innovative products is focused on the research of plant extracts with biostimulant properties. To this aim, Biolchim SpA has created a collection of botanical extracts whose potential use as biostimulants has to be screened according to their biological activity. Bioassays are small-scale tests that assess the biological activity of substances by evaluating their effect on living model organisms. In this study, an array of in vitro (root-tip elongation test) and in vivo (greenhouse growth tests) bioassays was set up and used to test the biostimulant properties of two botanical extracts. Overall results indicate that the array of bioassays is able to screen and differentiate the extracts according to their biological activity. The root-tip elongation bioassay is a first and rapid screening method of their hormone-like properties; the greenhouse growth bioassays provide information on their biostimulant performances in growth conditions similar to the open field and on their possible mode of application. The array of bioassays will be improved by including further in vitro and in vivo tests to fully unravel the biological properties of the extracts. The final goal is to screen the whole collection and classify the extracts according to their potential use as biostimulants. After the screening, prototypes will be formulated by combining different extracts and their efficacy will be tested in open field conditions.

Soybean Seedlings Tolerate Abrasion from Air-Propelled Grit

New tools for controlling weeds would be useful for soybean production in organic systems. Air-propelled abrasive grit is one such tool that performs well for in-row weed control in corn, but crop safety in soybean is unknown. Responses to abrasion by corn-cob grit of soybean seedlings were examined at VE, VC, VU, V1, V2 (emergence, cotyledon, unifoliate, first trifoliate, and second trifoliate, respectively) and combinations of these growth stages, in both greenhouse and field settings. Seedling leaf areas and dry weights in greenhouse experiments were reduced by treatments that included abrasion at VC, with the primary effect expressed through reductions in the size of the unifoliate leaf. In the field, soybean stand also was reduced by grit applications at VC, especially if followed by a second application at VU or V1. However, soybean yield was not reduced by grit applied at any soybean stage of growth. End-of-season weed dry weights did not differ from hand-weeded checks, and weeds did not impact soybean yields. Thus, abrasive grit for in-row weed control can be applied at least twice at VE through V2 growth stages without lowering soybean yield, but applications at VC probably should be avoided.

Production of AM fungus colonized seedlings under organic management: suitability of hydrolyzed fish vs. blood meal as options for N addition

The potential benefits of the arbuscular mycorrhizal (AM) symbiosis to crop growth and farm sustainability make utilization of AM fungus inoculum of particular interest to organic farmers. An important consideration in ensuring the colonization of vegetable seedlings by AM fungi during the greenhouse growth phase of production is supplying sufficient nitrogen and other nutrients for plant growth while limiting levels of phosphorus to avoid P-mediated inhibition of colonization. A greenhouse experiment was conducted to compare growth and AM fungus colonization of Allium porrum L. cv. Musselburgh seedlings in two organic potting media amended with high N and low P organic fertilizers vs. a chemical fertilizer solution known to produce well-colonized seedlings. Though amendment of the media with granular blood meal tended to produce the largest seedlings, formation of mycorrhizae was inhibited relative to 3 × per week additions of inorganic control or hydrolyzed fish fertilizers (4.5% vs. 28% and 16% of root length, respectively). A follow-up experiment in a controlled environment chamber demonstrated no detrimental effect of 3 × per week addition of blood meal in aqueous suspension relative to the chemical fertilizer. The incorporation of blood meal into the media had no impact on mycorrhizal development through the first 2 weeks, but inhibited development of new infection units and colonization of roots relative to the other treatments after 5 weeks (7% vs. 38% of root length). Proper choice of organic fertility amendment is essential to produce AM fungus colonized seedlings ready to take advantage of the symbiosis immediately upon outplanting.

Integral parameters for characterizing water, energy, and aeration properties of soilless plant growth media

Summary Over the last decade there has been a significant shift in global agricultural practice. Because the rapid increase of human population poses unprecedented challenges to production of an adequate and economically feasible food supply for undernourished populations, soilless greenhouse production systems are regaining increased worldwide attention. The optimal control of water availability and aeration is an essential prerequisite to successfully operate plant growth systems with soilless substrates such as aggregated foamed glass, perlite, rockwool, coconut coir, or mixtures thereof. While there are considerable empirical and theoretical efforts devoted to characterize water retention and aeration substrate properties, a holistic, physically-based approach considering water retention and aeration concurrently is lacking. In this study, the previously developed concept of integral water storage and energy was expanded to dual-porosity substrates and an analog integral oxygen diffusivity parameter was introduced to simultaneously characterize aeration properties of four common soilless greenhouse growth media. Integral parameters were derived for greenhouse crops in general, as well as for tomatoes. The integral approach provided important insights for irrigation management and for potential optimization of substrate properties. Furthermore, an observed relationship between the integral parameters for water availability and oxygen diffusivity can be potentially applied for the design of advanced irrigation and management strategies to ensure stress-free growth conditions, while conserving water resources.

Gas Diffusivity‐Based Design and Characterization of Greenhouse Growth Substrates

Growing plants in containerized substrates has long been common practice in horticulture. Containerized plants (e.g., greenhouse tomatoes) have restricted access to essential growth resources such as oxygen, water, and nutrients. Since a wide range of inorganic and organic materials, and different combinations thereof, are commonly used as growth media, detailed and comparable physical characterization is key to identify the best performing media. In this study, five potential growth media and two mixtures thereof were characterized based on soil gas diffusivity (Dp/Do, where Dp and Do are gas diffusion coefficients in soil air and free air, respectively) and an operationally defined critical window of diffusivity (CWD) representing the interval of air‐filled porosity between critical air filled porosity where Dp/Do ≈ 0.02 and interaggregate porosity. The Dp measurements were conducted with 100‐cm3 samples from wet to complete dry conditions achieved by stepwise air drying and equilibration of initially water‐saturated samples. A previously developed inactive pore and density‐corrected (IPDC) model was able to describe gas diffusivities for media with distinct inactive pore space in the interaggregate pore region reasonably well. An extended IPDC model was introduced for media exhibiting a second percolation threshold in the intra‐aggregate pore region. The analysis revealed comparable CWD values for the majority of the investigated media. The results further highlighted the importance of other major aspects (physical, chemical, and biological) of growth media characterization for optimal growth media design. A simple approach toward designing a gas diffusivity mixing model is presented to assist with selection of optimal mixing ratios of growth media with markedly different Dp/Do behavior.

Controlled root targeted delivery of fertilizer using an ionically crosslinked carboxymethyl cellulose hydrogel matrix

AimsThe recent increases in food prices caused by the corresponding increases in fertilizer costs have highlighted the demand for reducing the overuse of fertilizers in industrial agriculture. There has been increasing interest in developing plant root-targeted delivery (RTD) of fertilizers in order to address the problem of inefficient fertilizer use. The aim of this study is to develop a low cost controlled release device to deliver fertilizers to plant roots and thereby increase fertilizer use efficiency.MethodsThe Root Targeted Delivery Vehicle (RTDV) is formed by dissolving Carboxymethyl Cellulose (CMC) chains in water, mixing it with liquid fertilizer and crosslinking using iron and calcium salts. Basic measurements quantifying nutrient release and green house growth trials were carried out to evaluate fertilizer use efficiency on wheat growing in nutrient depleted soil media.ResultsGrowing wheat in nutrient depleted media showed that the RTDV permits a 78% reduction in the amount of fertilizer needed to achieve similar levels of plant yield in these conditions. Quantifying the losses associated with the RTDV synthesis showed that optimizing manufacturing could possibly increase this value as high as 94%. Furthermore, the delivery device showed a similar lifetime in soil to the plant’s growth cycle, delivering fertilizer over the course of the plant’s growth before removal from soil by degradation.ConclusionsThese results illustrate the importance of fertilizer delivery in facilitating absorption and may have potential to vastly increase the use efficiency of fertilizers in soil, resulting in a significant reduction of costs and environmental damage. With more in depth study to quantify the fertilizer release and refine the device, there is great potential for the use of the RTDV as an effective means to increase fertilizer use efficiency in agriculture.

Narcissus Cultivar Differences in Response to Saline Irrigation When Application Began Either Pre- or Postemergence

Salinity affects crop production worldwide and can be particularly problematic for ornamental plants. Daffodils (Narcissus sp. L.) are one of the most popular bulb plants, in demand for both landscapes and cut flowers. In this study we examined how moderate salinity, imposed as NaCl, affected growth, flower production, and leaf physiology when salinity treatment began either pre- or postemergence. Salinity did not affect growth rate or flower production for the three early-season cultivars (‘Dutch Master’, ‘Ice Follies’, and ‘Tete-a-Tete’) regardless of when salinity treatment began, but there were reductions in dry shoot biomass production under the highest salinity (50 mm NaCl). The mid-/late-season cultivar (‘Actaea’) had growth reduction and decreased flower production at the highest salinity when salinity treatment began preemergence. Within 28 days of greenhouse growth, the plants in the 50 mm NaCl treatment had carbon assimilation rates of only 25% to 32% of the 0 mm NaCl control. Sodium concentration increased 35% to 900% in the leaves in response to salinity for all cultivars when salinity treatment began preemergence but significantly increased only for ‘Actaea’ and ‘Tete-a-Tete’ (42% to 235%) when salinity treatment began postemergence. Potassium concentration in the shoot was mostly stable in response to salinity. The ability to maintain potassium (K) content within the plant may help daffodils tolerate the negative effects of sodium (Na). We believe that ‘Actaea’ was more negatively affected by salinity than the other three cultivars because, as a mid-/late-season cultivar, it had a much longer exposure period to salinity than the three early-season cultivars. However, moderate salinity does not seem to have a significant impact on growth and visual quality for ‘Dutch Master’, ‘Ice Follies’, or ‘Tete-a-Tete’ indicating that at least some saline water can be used for plant production without losses in plant quality.

Poplars with a PtDDM1-RNAi transgene have reduced DNA methylation and show aberrant post-dormancy morphology

The Arabidopsis thaliana DDM1 (Decreased DNA Methylation) gene is necessary for the maintenance of DNA methylation and heterochromatin assembly. In Arabidopsis, ddm1 mutants exhibit strong but delayed morphological phenotypes. We used RNA interference (RNAi) to suppress transcripts of two orthologous DDM1 paralogs in Populus trichocarpa and examined effects on whole plant phenotypes during perennial growth and seasonal dormancy. The RNAi-PtDDM1 transgenic poplars showed a wide range of DDM1 transcript suppression; the most strongly suppressed line had 37.5 % of the expression of the non-transgenic control. Genomic cytosine methylation (mC %) was 11.1 % in the non-transgenic control, compared with 9.1 % for the transgenic event with lowest mC %, a reduction of 18.1 %. An evaluation of greenhouse growth directly after acclimation of in vitro grown plants showed no developmental or growth rate abnormalities associated with the decrease in PtDDM1 expression. However, after a dormancy cycle and growth outdoors, a mottled leaf phenotype appeared in some of the transgenic insertion events that had strongly reduced PtDDM1 expression and DNA methylation. The phenotypic consequences of reduced DDM1 activity and DNA methylation appears to increase with cumulative plant propagation and growth.

Copper Phytoextraction and Phytostabilization by <i>Brachiaria decumbens</i> Stapf. in Vineyard Soils and a Copper Mining Waste

Brachiaria decumbens is a high biomass plant with great potential for phytoremediation of copper-polluted soils. The current study aimed to evaluate B. decumbens plants for phytoextraction and phytostabilization use in two different copper contaminated vineyard soils and a copper mining waste. Also, the macro and micronutrients uptake were evaluated after plants growth in copper contaminated soils. B. decumbens was cultivated in two vineyard soils (Inceptisol and Mollisol) and a copper mining waste for 47 days of growth in greenhouse. Then, B. decumbens’s nutrient uptake was evaluated, and it’s potential application in phytoremediation techniques for the phytoextraction and phytostabilization of copper contamination. B. decumbens exhibited high levels of biomass production at contaminated soils and no negative effect on macronutrients uptake was found. Copper contaminated soils affected micronutrients uptake by Brachiaria plants. This Brachiaria specie showed high potential on copper phytoextraction with accumulation of copper concentrations in the shoots and roots of 70 and 585 mg·kg-1 of dry mass, respectively, in the vineyard Inceptisol soil, after 47 days of growth. Mollisol soil and copper mining waste also exhibited high copper concentration in the biomass in the entire plant with 371 and 466 mg·kg-1, respectively. Although Brachiaria exhibited low levels of translocation factor for copper, this specie showed high potential for copper phytoextraction on Inceptisol, Mollisol and copper mining waste with 1900, 1156 and 1363 g·ha-1 of copper, respectively. In summary, B. decumbens plants showed high potential for copper phytoextraction and phytostabilization of copper on contaminated vineyard soils and copper mining waste

Isolation and evaluation of rhizosphere actinomycetes with potential application for biocontrol of Verticillium wilt of cotton

Verticillium wilt of cotton, caused by Verticillium dahliae, is a serious soil-borne disease worldwide. In this study, a total of 712 actinomycete cultures were isolated from the rhizosphere of crops and characterized for their antagonistic potential against V. dahliae. Four isolates (ZY-153, B-49, X-4 and Z-13) were selected based on their ability to efficiently inhibit V. dahliae growth and conidia production in vitro by using a two-stage screening process. The four isolates produced extracellular fungal cell-wall degrading enzymes including chitinase, β-1,3-glucosidase, cellulase and protease when cell walls of V. dahliae were the sole carbon source. Microscopic observation indicated that the isolates coiled around fungal hyphae, causing them to lyse. The four isolates were identified using morphological and physiological tests combined with 16S rRNA-based molecular analysis. Isolate ZY-153 was identified as Streptomyces cyaneofuscatus, B-49 Streptomyces kanamyceticu, X-4 Streptomyces rochei and Z-13 Streptomyces flavotricini. In a greenhouse study, the biocontrol efficacy of the four isolates against Verticillium wilt of cotton ranged from 18.7 to 65.8%. The isolates successfully colonized the cotton rhizosphere in a wilt-sick field study when the powdered biocontrol agent was applied either as a seed coating (biocontrol efficacy 13.5–48.0%) or as a soil inoculation (biocontrol efficacy 17.8–51.4%). Correlative analysis indicated that there was a significant positive correlation between the biocontrol efficacy of the isolates and their biocontrol properties. The four Streptomyces isolates produced siderophores and indole acetic acid (IAA) in vitro and one isolate (X-4) significantly increased cotton growth in greenhouse and field studies. Our results indicate that the selected Streptomyces isolates are promising agents for the biocontrol of Verticillium wilt of cotton.

Modeling of Tomato Seedling Growth in Greenhouse

This study was undertaken to model the growth of tomato seedlings under greenhouse conditions. The micro-environment of the seedlings (temperature and solar radiation) was correlated with the seedling growth factors. Seed emergence was studied for five different temperatures, and a mathematical model was developed to fit the data to determine relationship between seed germination and soilless medium temperature. In post-emergence phase, a model was developed to estimate the dry weight attained by the seedlings as a function of cumulative heat units (CHU) and cumulative solar radiation (CSR). It was observed that the number of days required for seedling emergence was a function of average root medium temperature. Tomato seedlings emerged in 12 days at average root medium temperature of 20 and 35 °C, while the minimum duration was observed to be 7 days at 30 °C. The power model represented the seedling emergence behavior with correlation coefficient of 0.96. The growth of tomato seedlings after emergence was affected by both CHU and CSR. Modified Gompertz model explained the post emergence tomato seedling growth under different climatic variations with correlation coefficient from 0.96 to 0.97.

Impact of rhizobial inoculation on Acacia senegal (L.) Willd. growth in greenhouse and soil functioning in relation to seed provenance and soil origin

Rhizobial inoculation has a positive impact on plants growth; however, there is little information about its effect on soil microbial communities and their activity in the rhizosphere. It was therefore necessary to test the effect of inoculation of Acacia senegal (L.) Willd. seedlings with selected rhizobia on plant growth, structure and diversity of soil bacterial communities and soil functioning in relation to plant provenance and soil origin. In order to carry out this experiment, three A. senegal seeds provenance from Kenya, Niger, and Senegal were inoculated with selected rhizobial strains. They have been further grown during 4 months in greenhouse conditions in two non-disinfected soils, Dahra and Goudiry coming respectively from arid and semi-arid areas. The principal component analysis (ACP) showed an inoculation effect on plant growth, rhizospheric bacterial diversity and soil functioning. However, the performances of the rhizobial strains varied in relation to the seed provenance and the soil origin. The selected rhizobial strains, the A. senegal provenance and the soil origin have modified the structure and the diversity of soil bacterial communities as measured by principal component analysis/denaturing gradient gel electrophoresis analyses. It is interesting to note that bacterial communities of Dahra soil were highly structured according to A. senegal provenance, whereas they were structured in relation to rhizobial inoculation in Goudiry soil. Besides, the impact of inoculation on soil microbial activities measured by fluorescein diacetate analyses varied in relation to plant provenance and soil origin. Nevertheless, total microbial activity was about two times higher in Goudiry, arid soil than in Dahra, semi-arid soil. Our results suggest that the rhizobial inoculation is a suitable tool for improving plants growth and soil fertility. Yet, the impact is dependent on inoculants, plant provenance and soil origin. It will, therefore, be crucial to identify the appropriate rhizobial strains and plant provenance or species in relation to the soil type.

Evaluation of Multispecies Plant-Growth-Promoting Consortia for the Growth Promotion of Jatropha curcas L.

Direct interactions that occur between members of different microbial types often result in the promotion of key processes that benefit plant growth and health. In the present study, four isolates, Brevibacillus brevis (MS1), Bacillus licheniformis (MS3), Micrococcus sp. (MS4), and Acinetobacter calcoaceticus (MS5), were used to develop multispecies consortia. They have the ability to produce IAA, solubilize inorganic P, and produce ACC deaminase and siderophore. The growth profile of MS1 was similar in monospecies and mixed-species cultures, but about a 24 % increase in mean growth rate was recorded for MS5. They enhanced the growth of Jatropha curcas in individual trials. Plant growth further improved maximally when the three were applied together. All four strains enhanced Jatropha growth in greenhouse and field experiments. Co-inoculation provides the largest and most consistent increases in shoot weight, root weight, total biomass, shoot and root length, total chlorophyll, shoot width, and grain yield.

Five Year Field Evaluation of Prosopis alba Clones on pH 9–10 Soils in Argentina Selected for Growth in the Greenhouse at Seawater Salinities (45 dS m−1)

Prosopis alba seedlings, that grew at the 45 dS m−1 salinity level in a previous study of growth and survival of Argentine and Peruvian Prosopis, were propagated by rooting cuttings and established in a seed orchard/long term evaluation trial on soils with low salinity (EC 5.1–7.5 dS m−1) but high pH (8.9 to 10.2). A pH gradient occurred in the field with values ranging from pH 9.4 in block 1 to pH 10.3 in block 5. After five years growth, almost all of the clones had a mean height greater than 4 m and one clone was more than 5 m. Ten of the 21 tested clones had significantly greater biomass growth than the three seed propagated check varieties. The broad-sense (i.e., clone mean) heritability was estimated to be 0.45 for biomass, 0.53 for diameter and 0.59 for height indicating that strong genetic gains should be possible by selecting and vegetatively propagating the best genotypes. In the block with the highest pH values, two clones that appear to be P. alba × P. ruscifolia hybrids (i.e., P. vinallilo) had the greatest biomass. Correlations between growth during the last two months in the high salinity hydroponic greenhouse selection system and growth in the field were significant (R2 = 0.262) and positive, although the relationship was negative for putative P. vinallilo clones (R2 = 0.938). The several fold increase in biomass of some of the clones over the three check varieties, suggests that the greenhouse screen was successful in identifying superior salt tolerant clones. Apparently whether the greenhouse seedlings had lesser (~1 cm) to greater (~3 cm) height growth was not as important as just having a healthy live apical meristem. The observed salt tolerance of the putative P. vinalillo clones may prove useful as rootstocks for recently described high pod producing P. alba clones.

A Design and Implementation of Mobile Application SREMS

Based on Smart Phone, this study added and implemented the mobile App to the existing IT agriculture system, which system automatically controlled green house's growth environment. Because the mobile App characterfully possesses high portability, limited resource, mobile wireless network support, enterprise mobile computing support, etc., the hybrid-App should be inevitably adopted. The hybrid App can minimize resource consumption for performing related duties and also, in spite of the mobile device's limits, it can derive high performance, in which facts the system can ensure the service-based architecture's reliance and also, implements the highly sophisticated functionality as well. Through the proposed system, the study expects to contribute to improve quality of life as well as to increase farmer's income through IT-based agriculture system development.

Remote Image Acquisition and Transmission Framework for Monitoring Plant Growth Based on ARM9

In order to monitor the plant growth in greenhouse, a new method based on GPRS and Internet wireless communication technology was introduced in this paper. It is a system involving S3C2410 of ARM9 kernel as the microprocessor chip, which can be run in Linux operating system and takes the wireless transmission mode of GPRS+Internet as an adoption. The structure of the whole system, hardware design and image acquisition and transmission framework were introduced. A detailed explanation was given about planted method of operating system in the paper.

Biocontrol of seed pathogens and growth promotion of common bean seedlings by Trichoderma harzianum

The objective of this work was to evaluate isolates of Trichoderma harzianum regarding biocontrol of common bean seed-borne pathogens, plant growth promotion, and rhizosphere competence. Five isolates of T. harzianum were evaluated and compared with commercial isolate (Ecotrich), Carboxin+Thiram, and an absolute control. Bean seeds of the cultivar Jalo Precoce, contaminated with Aspergillus, Cladosporium, and Sclerotinia sclerotiorum, were microbiolized with antagonists, and seed health tests were carried out. Isolates were evaluated on autoclaved substrate and in field conditions. Ten days after sowing (DAS), plant length was measured. To test rhizosphere competence, isolates were applied in boxes containing autoclaved washed sand, and root colonization was evaluated at 10 DAS, using five plants per box. The most effective isolates in the seed health tests were: CEN287 and CEN289 to control Aspergillus; the commercial isolate to control Cladosporium; and CEN287 and CEN316 to control S. sclerotiorum. Isolates CEN289 and CEN290 promoted bean growth in greenhouse and field. Seed treatment with T. harzianum reduces the incidence of Aspergillus, Cladosporium, and S. sclerotiorum in 'Jalo Precoce' common bean seeds.

Photosynthetic capacity, photochemical efficiency and chlorophyll content of three varieties of Labisia pumila Benth. exposed to open field and greenhouse growing conditions

Three varieties (Alata, Pumila and Lanceolata) of Malaysian indigenous medicinal herb Labisia pumila Benth. grown in greenhouse and open field were tested to evaluate and compare their photosynthetic and maximal quantum efficiency of photosystem II (F v/F m) reactions. Every variety grown in greenhouse demonstrated higher light-saturated photosynthetic capacity than in the open field. The diurnal net photosynthesis (A) curve in the open field also displayed dual peaks with lower daily average A compared to the greenhouse. Varieties Alata and Pumila were found to acclimatize better under both growing conditions. The diurnal patterns of F v/F m indicated that plants grown under greenhouse encountered less photoinhibition than in open field condition. A decrease in chlorophyll (chl) a/b ratio in leaves of greenhouse plants with significant increase in chl b was observed. This study indicates that var. Alata and var. Pumila have the capacity to acclimatize to greenhouse growth condition.

Greenhouse and field cultivations of antigen-expressing potatoes focusing on the variability in plant constituents and antigen expression

The production of plant-derived pharmaceuticals essentially requires stable concentrations of plant constituents, especially recombinant proteins; nonetheless, soil and seasonal variations might drastically interfere with this stability. In addition, variability might depend on the plant organ used for production. Therefore, we investigated the variability in plant constituents and antigen expression in potato plants under greenhouse and field growth conditions and in leaves compared to tubers. Using potatoes expressing VP60, the only structural capsid protein of the rabbit haemorrhagic disease virus (RHDV), CTB, the non-toxic B subunit (CTB) of the cholera toxin (CTA-CTB(5)) and the marker protein NPTII (neomycinphosphotransferase) as a model, we compare greenhouse and field production of potato-derived antigens. The influence of the production organ turned out to be transgene specific. In general, yield, plant quality and transgene expression levels in the field were higher than or similar to those observed in the greenhouse. The variation (CV) of major plant constituents and the amount of transgene-encoded protein was not influenced by the higher variation of soil properties observed in the field. Amazingly, for specific events, the variability in the model protein concentrations was often lower under field than under greenhouse conditions. The changes in gene expression under environmental stress conditions in the field observed in another event do not reduce the positive influence on variability since events like these should excluded from production. Hence, it can be concluded that for specific applications, field production of transgenic plants producing pharmaceuticals is superior to greenhouse production, even concerning the stability of transgene expression over different years. On the basis of our results, we expect equal or even higher expression levels with lower variability of recombinant pharmaceuticals in the field compared to greenhouse production combined with approximately 10times higher tuber yield in the field.