Open Greenhouse Research Articles

Analysis of cultivar variability in arbuscular mycorrhizal responsiveness in soybean varieties

ABSTRACT In modern agricultural systems, high crop yields depend on the high input of orthophosphate-based fertilizers. Owing to the looming scarcity of rock phosphate in the near future, utilization of arbuscular mycorrhizal (AM) symbiosis for the efficient uptake of phosphorus is a necessary approach to maintain crop yield. Plant responsiveness to AM fungi is assessed based on the difference in biomass between plants with and without AM fungal inoculation. Soybean is a plant which establishes both mycorrhizal and rhizobial symbiosis. Therefore, it is difficult to eliminate the symbiotic effects of rhizobial nitrogen fixation during long-term cultivation until soybean harvest. In this study, Bradyrhizobium diazoefficiens USDA110 was inoculated at the same time as soybean seeds were sown, and soybean was grown under Rhizophagus irregularis inoculated and non-inoculated conditions to verify whether the mycorrhizal inoculation effect was observed at the yield level. In 2013, two soybean cultivars Tachinagaha and Williams 82, were grown at five levels of phosphate availability (0, 5, 10, 20, and 40 kg P 10a−1) in an open greenhouse in Tsukuba, Japan. Among the several growth indices analyzed, seed weight per plant was selected as a reliable indicator of plant response. Mycorrhizal inoculation showed a positive effect on soybean under 20 kg P 10a−1 phosphorus fertilization for Williams 82, while Tachinagaha showed almost no effect. This trend was replicated in 2014 and 2016, indicating that Tachinagaha has a lower AM responsiveness than Williams 82.

Biosolid Mixtures Applied in Tropical Soils and Their Effect on Coriandrum sativum and Ocimum basilicum Nutritional Uptake

Agricultural soils are degraded worldwide as result of anthropogenic activities; environmental contamination; and excessive use of chemicals, fertilizers, and pesticides. Scientists are concerned about this problem; during the past few years sewage compost and sludge have been used as alternatives to improve the soil’s physical and chemical characteristics. Recycling solid waste residues can be a cost-effective way to reduce landfill material disposal and improve macro and micronutrients’ availability in agricultural soils. In this study, two types of biosolids (compost and sludge) were added to tropical soils (coloso and voladora series) to improve the nutritional content in two edible herbs (basil and coriander). Soil mixtures were made by volume percentage; compost was constant, at 25%, and soil and sludge were incorporated in different proportions to complete the 100% (25 comp/75 soil, 25 comp/62.5 soil/12.5 sludge, 25 comp/50 soil/25 sludge and 25 comp/37.5 soil/37.5 sludge). pH and electrical conductivity were measured in soil mixtures. Basil and coriander were cultivated in pots for 30 days at an open greenhouse (5 replicates per soil mixtures). Germination percentage, stems’ length, total chlorophyll (SPAD 502), acid digestions of plant tissues and an ICP-OES analysis were performed for both plants cultivated in all the soil mixtures. In voladora soil, the pH increased from 4.55 ± 0.10 to 5.64 ± 0.22 and EC from 0.0563 ± 0.0003 dS/m to 1.39 ± 0.01 dS/m in a 25% comp/37.5% soil/37.5% sludge mixture. In the coloso soil, the pH increased from 6.38 ± 0.13 to 6.82 ± 0.07 and electrical conductivity from 0.117 ± 0.001 to 1.310 ± 0.009 dS/m in 25% compost/37.5% soil/37.5% sludge mixture. Significant differences (p < 0.05) were found in the chlorophyll content and stem length for both plants. The highest chlorophyll value was in basil leaves from a 25% compost/50% soil/25% sludge mixture (43.20 ± 074) compared to the coloso soil (26.99 ± 0.43). In the voladora soil, the highest chlorophyll content was in a 25% compost/37.5% soil/37.5% sludge mixture (39.97 ± 0.83). In coriander leaves, the highest chlorophyll content was 33.01 ± 0.84 in the 25% compost/62.5% coloso/12.5% sludge mixture. In the voladora soil, chlorophyll content in leaves did not show a significant difference between treatments. Larger basil stems were found at 25% compost/75% voladora mixture (17.50 ± 2.39 cm) and in a 25% compost/62.5% coloso/12.5% sludge mixture (9.95 ± 0.71 cm) compared to control plants (3.45 ± 0.18 cm). Greater coriander stems were observed in a 25% compost/50% voladora/25% sludge mixture (2.43 ± 0.11 cm) and in a 25% compost/50% coloso/25% sludge mixture (2.17 ± 0.10 cm) compared to control plants (2.05 ± 0.07 cm). Macro and micronutrient content in plants increased with biosolids’ incorporation to soils. Mg content in basil leaves increased from 8.61 ± 0.70 mg/g in the voladora soil to 10.31 ± 0.60 mg/g in a 25% compost/37.5% soil/37.5% sludge mixture. In coriander leaves, Mg increased from 6.91 ± 0.06 mg/g in a 25% compost/75% soil mixture to 9.63 ± 0.02 mg/g in a 25% compost/50% soil/25% sludge mixture. The Mn uptake by basil leaves increased from 0.076 ± 0.005 mg/g in the coloso soil to 0.152 ± 0.019 mg/g in a 25% compost/75% soil mixture. In coriander leaves, Mn increased from 0.357 ± 0.002 mg/g in a 25% compost/75% soil mixture to 0.651 ± 0.006 mg/g in a 25% compost/37.5% soil/37.5% sludge mixture.

Open field hardening improves leaf physiological drought tolerance in young plants of Sindora siamensis.

The effect of drought stress on leaf physiology was studied in 10-month-old plants of Sindora siamensis . Plants were either placed in an open greenhouse (unhardening; UH) or in an open field (open field hardening; H) for 45days. Both the UH and H plants stopped receiving water (D) until the initial drought injury and then rewatered (R) until complete recovery. Results showed necrosis in the leaves of UH+D, while H+D showed wilting at Day 7 after drought. A greater degree of necrosis was found in UH+D+R but made complete recovery in H+D+R at Day 4 after rewatering. Drought stress resulted in decreased leaf area in H, and reduced leaf and stem water status, PSII efficiency, net photosynthetic rate, stomatal conductance and transpiration rate in both UH and H. It also resulted in an increase in water use efficiency in both UH and H. Electrolyte leakage and malondialdehyde contents in UH were markedly increased due to drought stress. These results suggest that unhardened young plants of Sindora exposed to drought exhibited enhanced stomata behaviour by minimising open stomata and transpiration, resulting in high efficiency of water usage. However, there was still membrane damage from lipid peroxidation, which caused necrosis. Open field hardened plants exposed to drought demonstrated reduced open stomata and transpiration, thereby preserving leaf and soil water status and enhancing water use efficiency. This may be a reduction in lipid peroxidation though an oxidative scavenging mechanism that causes a slight alteration in membrane stability and a slight necrosis.

Expression analysis of candidate genes as indicators for commencing drought stress in starch potatoes

AbstractDrought stress is a major problem for potato production and will be of grave importance due to climate change and the resulting temperature peaks along with drought periods in the vegetative growth phase of potato. Plants, as sessile organisms, adapt to their environment morphologically as well as biochemically. To cope better with abiotic stresses like drought, plants developed strategies like reactive oxygen species (ROS) detoxification and fast reacting stomatal closure, as well as signalling cascades leading to a quick response to stress. This study aimed at analysing eight genes of interest, derived from a former proteomic study, and determining their suitability for detection of commencing drought stress in early growth stages of potato. For this aim, six starch potato genotypes, which differed in stress response in previous studies, were examined for plant growth and physiological parameters in two experiments in an open greenhouse after seven and 14 days of stress. Besides lower shoot biomass after drought stress, which was already visible after seven days and became stronger after 14 days, weaker root growth was also detected after 14 days. The observed differences between the experiments can presumably be explained by temperature peaks and high radiation prior to and during the first experiment, which took place earlier in the year. The expression of the eight genes was studied in young leaves of four genotypes after 7 days of water withdrawal. Gene expression patterns were dependent on the studied genes. Three genes, cell wall/vacuolar inhibitor of fructosidase (INH1), peroxidase 51‐like (POD) and subtilase family protein (SBT1.7) showed consistent changes in gene expression after seven days of stress between all genotypes. The INH1 gene was found to be upregulated in all genotypes in two independent experiments after drought stress. This correlates with the results at the protein level, where INH1 was also found to be higher abundant in two genotypes of potato (Wellpott et al., DGG‐Proceedings 10, 2021). Therefore, this gene might be an appropriate candidate for the detection of commencing drought stress in potato.

Phytopathological and biochemical impacts of Trichoderma harzianum and certain plant resistance inducers on faba bean root rot disease

BackgroundFaba bean attacked by soil-borne pathogens causing root rot disease. This disease has serious damage to both plant stand and produced yield. The present study aimed to evaluate effectiveness of the bioagents; Trichoderma harzianum and some plant resistance inducers as fungicide alternatives against root rot disease incidence at both pre- and post-emergence growth stages.ResultsUnder open greenhouse conditions, the incidence of faba bean root rot in pre- and post-emergence growth phases was considerably reduced by using six inorganic salts and five antioxidants individually or combining with each other or with the bio-stimulator T. harzianum that exceeded the used fungicide, Rhizolex-T. Application of enervit agitated the highest significant defensive impact during pre-emergence stage versus root rot incidence (5.0%), followed by calcium sulfate and [cysteine + T. harzianum] (6.7%). At post-emergence stage, majority of the treatments completely suppressed (100.0%) root rot incidence, except vitamax plus and the fungicide (Rizolex-T) which expressed by 91.7 and 18.8%, respectively. Duplicate irrigations of 23 treatments after faba bean dressing improved the synthesis of different protein contents with the 2nd of which enhanced higher protein contents than the 1st one, except [T. harzianum + vitamin E + vitamin C + enervit + selenium + vitamax plus], [T. harzianum + vitamax plus] and cysteine. Disodium phosphate induced the highest catalase (CAT) activity (1820.8 and 1677.2 U/g FWt) after both irrigations. [T. harzianum + vitamax plus] and vitamin E induced the highest peroxidase (POD) activity 217.4 and 356.9 U/g FWt after 1st and 2nd irrigations, respectively. Disodium phosphate and [T. harzianum + vitamin E + vitamin C + enervit + selenium + vitamax plus] induced the highest chitinase (CHIA) activity 52.8 and 54.4 U/g FWt after 1st and 2nd irrigations, respectively. Application of disodium phosphate, calcium sulfate, potassium metabisulfite, sodium sulfate, cysteine, [cysteine + potash alum], enervit, vitamin E, [vitamin E + vitamin C + enervit + selenium + vitamax plus], [T. harzianum + enervit], [T. harzianum + selenium], [T. harzianum + vitamin E], [T. harzianum + vitamin E + vitamin C + enervit + selenium + vitamax plus] and vitamin C stimulated the formation of new protein bands on SDS-PAGE after the 2nd irrigation treatment.ConclusionsSuch treatments are considered good and environmentally safe alternatives against root diseases for getting rid of the negative effects of fungicides.

Simplification effect of lead soil contamination on the structure and function of a food web of plant-associated insects

Anthropogenic activities such as mining, industry, urban waste production, and the overuse of agricultural inputs may result in the contamination of the environment by heavy metals, which are toxic to organisms mainly due to their potential to accumulate in tissues. This contamination causes the simplification of aquatic and edaphic food webs, which show impaired structure and function. We investigated whether soil contamination with heavy metal at the permitted concentrations affects the structural or functional properties of a terrestrial food web of insects living in the aboveground parts of a plant. As study models we used lead (Pb) and kale-associated insects. Kale plants (Brassica oleracea var. acephala) were grown in soil experimentally contaminated with four lead nitrate concentrations: 0 (control), 144 (T1), 360 (T2), and 600 (T3) mg/kg of soil. The experiment was conducted in an open greenhouse for natural insect colonization. The insects were collected twice in the field using trap bags attached to the plant leaf and by direct removal. In general, we observed a simplification of the food web as the Pb concentrations increased, resulting in visually smaller food webs. The food web metrics decreased from the T2 treatment (the Pb limit for agricultural soils). Structurally, the Number of Species (whose values were highly positively correlated to the Number of Links and Link Density values) decreased with increasing contamination, while Connectance increased. Functionally, the Predator/Prey Ratio and Trophic Vulnerability and Generality became lower. This study shows that soil contamination by Pb can simplify insect food webs in the aboveground parts of plants, negatively affecting the structure and function of the webs, even at permitted concentrations.

Flowering plants in open tomato greenhouses enhance pest suppression in conventional systems and reveal resource saturation for natural enemies in organic systems

Vegetable production in open greenhouses is often associated with high inputs of synthetic pesticides. Introducing flowering plants into such greenhouses may promote the top-down pest suppression by natural enemies and reduce the reliance on pesticide use. However, it is not known how effective this practice is in organically and conventionally managed greenhouse crops. We assessed the influence of introducing flowering plants into open greenhouses with organically and conventionally managed tomato crops on the abundance of pests, natural enemies (NE), pollinators, and crop yield. We monitored tomato crops during two years in two greenhouses at four organic farms and four conventional farms that used integrated pest management (IPM). On each farm one greenhouse contained flower islands of basil (Ocimum bacilicum), marigold (Tagetes patula) and alyssum (Lobularia maritima), and the other greenhouse served as a control. Organic farms had yields comparable to conventional farms, a lower abundance of pests, less pest injury, and a higher abundance of NE. The cumulative pest:NE ratio was 9 for organic and 38 for conventional management. The effect of introducing flowering plants on arthropods depended significantly on the type of farm management. Conventionally managed tomato crops in greenhouses with seven flower islands per 100 m2 had 18% lower pest abundance compared to the control greenhouses without flowers, while flower islands did not significantly influence arthropod abundances in organically managed tomato crops. Tomato plants had a higher abundance of pests than the three introduced plant species in conventionally managed greenhouses, while marigold had a higher abundance of pests than tomato in organically managed greenhouses. Alyssum supported a relatively low pest abundance and high abundance of NE and pollinators. Our findings indicate that NE in IPM-conventionally managed greenhouses can benefit from resources provided by flowering plants, resulting in reduced pest abundance, while in organically managed greenhouses the conditions are already favourable for the suppression of pests and addition of floral resources does not further improve the effectiveness of NE. This finding highlights the potential of agroecological and organic management to reduce the reliance on synthetic pesticides without yield reduction.

Screening of seed germination requirements of some native plants of the Mediterranean region

In the present study, we aim to investigate the seed germination conditions of three Lamiaceae widespread in the Mediterranean region and growing spontaneously in Algeria: Marrubium vulgare L., Rosmarinus officinalis L. and Thymus algeriensis Boiss. et Reut. Two experiments were carried out: (i) Ex vitro germination test: without pre-treatment. Species seeds were sowed directly in the soil under continuous darkness at 4 °C, room temperature (23±2 °C), photoperiod (16 h/light/25±1 °C, 8 h/dark/15±1 °C) and in open green house conditions. (ii) In vitro germination test was achieved by incubating sterile and soaking seeds in various doses of gibberellic acid (GA3) (0, 125, 250, 500 mg/L) under photoperiod (16 h/light/25±1 °C, 8 h/dark/15 ± 1 °C) and continuous darkness (16 h/dark/25±1 °C, 8 h/dark/15±1 °C).In ex vitro experiment, results showed that the combination of darkness and cold, ambient temperature and photoperiod did not present any significant effect (P > 0.05) on germination success rate (GSR) in the three tested species. However, low GSR (23.3%) was observed in both Thymus algeriensis and Marrubium vulgare when seed samples were placed in a greenhouse. An effective sterilization protocol was developed to successfully germinate seeds under in vitro conditions where mercuric chloride (HgCl2) was used as the most powerful sterilizing agent. In in vitro experiment, Thymus algeriensis seeds presented high GSR (66.7% to 83.3%). Furthermore, the application of GA3 at 125, 250, 500 mg/L and continuous darkness resulted in significantly high GSR (P < 0.001) in Marrubium vulgare with 68.3%, 71.6%, 73.3% and 71.7%, respectively. The interaction of GA3 at 125 mg/L and darkness significantly increased the GSR to 93.3%. In addition, GA3 doses, photoperiod-dark and the interaction GA3 × phoroperiod-dark significantly influenced the germination speed (P < 0.001) in Marrubium vulgare. While, all the treatments: GA3 doses, photoperiod-dark and their interactions did not significantly affect the seed germination (P > 0.10) in Rosmarinus officinalis, which showed a very low GSR (6.7%).

Eco-physiological response and genotoxicity induced by crude petroleum oil in the potential phytoremediator Vinca rosea L

BackgroundPhytoremediation is determined as an emerging green technology suitable for the safe remediation and restoration of polluted terrestrial and aquatic environments. In this study, the assessment of an ornamental plant, Vinca rosea L., as a phytoremediator of crude oil in polluted soils was conducted. In an open greenhouse experiment, plants were raised in sandy-clayey soils treated with 1, 3, 5, and 7% oil by weight. The experiment was conducted over 5 months. ResultsTotal petroleum hydrocarbon (TPH) degradation percentage by V. rosea after a 5-month growth period ranged from 86.83 ± 0.44% to 59.05% ± 0.45% in soil treated with 1 and 7%, respectively. Plants raised in polluted soils demonstrated a dramatic reduction in germination rates, in addition to growth inhibition outcomes shown from decreased plant height. An increase in branching was observed with an increase in oil pollution percentages. Moreover, the phytomass allocated to the leaves was higher, while the phytomass witnessed lower values for fine roots, flowering and fruiting when compared to the controls. Apart from the apparent morphological changes, there was a decrease in chlorophyll a/b ratio, which was inversely proportional to the oil pollution level. The contents of carotenoids, tannins, phenolics, flavonoids, and antioxidant capacity were elevated directly with an increase in oil pollution level. The start codon-targeted (SCoT) polymorphisms and inter-simple sequence repeat (ISSR) primers showed the molecular variations between the control and plants raised in polluted soils. The genetic similarity and genomic DNA stability were negatively affected by increased levels of crude oil pollution. ConclusionsThe ability of V. rosea to degrade TPH and balance the increased or decreased plant functional traits at the macro and micro levels of plant structure in response to crude oil pollution supports the use of the species for phytoremediation of crude oil-polluted sites. The genotoxic effects of crude oil on V. rosea still require further investigation. Further studies are required to demonstrate the mechanism of phenolic, flavonoid, and antioxidant compounds in the protection of plants against crude oil pollution stress. Testing different molecular markers and studying the differentially expressed genes will help understand the behavior of genetic polymorphism and stress-resistant genes in response to crude oil pollution.

Impact of Folic Acid in Modulating Antioxidant Activity, Osmoprotectants, Anatomical Responses, and Photosynthetic Efficiency of Plectranthus amboinicus Under Salinity Conditions.

Salinity is a major threat to the sustainability of agricultural production systems. Salt stress has unfavorable implications on various plant physio-morphological and biochemical reactions, causing osmotic and ionic stress. Exogenously applied folic acid (FA) may at least provide one mechanism to evade the injurious stress effects of saline irrigation water on Plectranthus amboinicus. In this regard, two pot trials were performed during the 2018–2019 and 2019–2020 seasons in an open greenhouse of an experimental farm (29°17'N; 30°53'E) in Fayoum, Egypt. We tested four levels of saline irrigation water (SW): 34, 68, and 102 mM NaCl, plus tap water as the control = 0), combined with FA at three concentrations (25 and 50 μM, plus spray with distilled water as the control = 0). The growth parameters, biochemistry, physiology, elemental leaf status, essential oil content, and anatomical responses were assessed. Salt markedly reduced photosynthetic productivity [Fv/Fm and performance index (PI)], total chlorophyll [soil plant analysis development (SPAD)], and leaf osmoprotectant compounds, i.e., total soluble sugars (TSS), free amino acids, proline, and total phenolics, thus hampering P. amboinicus growth and essential oil yield. However, the addition of FA as a foliar spray to P. amboinicus irrigated with saline water induced increases in Fv/Fm, SPAD, and PI. These were linked with enriched stem anatomical structures, leaf osmoprotectant compounds, and enhanced leaf enzymatic activity, e.g., superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, glutathione, ascorbic acid, and antioxidant content. Under salt stress, supplementation of 25 and 50 μM FA increased the growth and production of essential oil by 27.8 and 55.6%, respectively, compared with no applied FA. The highest growth characteristics and elemental leaf contents were obtained when P. amboinicus was irrigated with 0 mM saline water and treated foliarly with 50 μM of FA compared with non-treated plants. Overall, these data showed that foliar spraying with FA reduces the impact of salt stress on P. amboinicus irrigated with saline water.

Heterogeneous effects of climatic conditions on Andean bean landraces and cowpeas highlight alternatives for crop management and conservation

The use and conservation of agrobiodiversity have become critical to face the actual and future challenges imposed by climate change. Collecting phytogenetic resources is a first step for their conservation; however, the genetic material must be analysed to understand their potential to improve agricultural resilience and adaptation to the new climatic conditions. We have selected nine Phaseolus vulgaris, one P. lunatus and two Vigna unguiculata landraces from two different climatic backgrounds of the Andean region of South Ecuador and one P. vulgaris commercial cultivar, and we grew them under two different conditions of temperature and humidity (open field and greenhouse). Then, we recorded data for 32 characters of plant architecture, flower and fruit characteristics and yield, and 17 events in the phenology of the plants. We analysed the impact of treatment on species, climatic background, and each of the landraces, and identified both characters and landraces that are mostly affected by changes in their environmental conditions. Overall, higher temperatures were benign for all materials except for two P. vulgaris landraces from cold background, which performed better or developed faster under cold conditions. Finally, we calculated a climate resilience landrace index, which allowed us to classify the landraces by their plasticity to new environmental conditions, and found heterogeneous landrace susceptibility to warmer conditions. Two P. vulgaris landraces were highlighted as critical targets for conservation.

Hydroponic Technique: A New approach for Crop Production at Trans Himalayan High-altitude Cold Desert Regions of India

Aims: The trans-Himalayan high-altitude cold desert regions of India is characterized by a rugged topography at an altitude ranging from 2550 to 7742 meters above sea level. It has a vast geographical area of 72976 km2 with very little cultivated area of about 13726 hectare. Hydroponic is a soilless cultivation technique which may produce fresh vegetable in areas where environmental stress (cold, heat, dessert etc.) and limited space or on non-arable land is a major constrains for agriculture production.&#x0D; Methodology: The experiment was conducted under open natural ventilated double layer polycarbonate green house in cold desert high altitude conditions of Leh, India. The hydroponic structures were designed for crop production (viz. leafy greens, vegetables, fruits etc) in deep water culture (DWC) and nutrient film technique (NFT) hydroponic techniques and compared them with conventional soil grown system. Nutrient solution for growing vegetables was prepared and standardized.&#x0D; Results: The result obtained has shown that crop yield was significantly higher in hydroponic system as compared to traditional system for all crops. The recorded increase in yield for various crops in hydroponic system compared to soil grown system were: arugula 221%, atriplex 248%, coriander 288%, fenugreek 208%, lettuce 293%, mint 237%, mustard 227%, spinach 294%, cucumber 533%, strawberry 280%, summer squash 229% and tomato 345% which were significantly higher. Hydroponics can be explored to grow vegetables round the year especially for leafy greens. The hydroponic systems may come out as a valuable asset to forward and remote area of trans-Himalayan region for growing fresh vegetables where cultivated land and availability of the water are the limiting factors for crop production.

Architecture of Cocoa Genotypes in Colombia as Affected by Bud Type, Grafting Technique, and Pruning

Organization of plant aerial parts and root distribution, environmental conditions such as light, temperature, humidity and agronomic practices (grafting and pruning) influences the final architecture of the plant. Most of cocoa plantations in Colombia belong to the plagiotropic type that emit branches and suckers in a disorderly way, which leads to an unbalanced development, this makes it difficult to manage. To search for cocoa plants with better architecture, we evaluated the effect of the type of the bud (orthotropic and plagiotropic), the grafting techniques (approximation and patch grafting) and pruning (structural and conventional) on ICS 95 and CCN 51 clones. The monitoring was carried out at an open greenhouse and field. Plants obtained from orthotropic buds and approximation grafting had lower bifurcation angles, 42% more leaves and 50% more branches. The structural pruning had a positive influence on the architectural variables, which presenteda higher conversion (8.68%) of fresh weight of cocoa pod into dry weight of cocoa beans, meanwhile CCN 51 trees showed a higher conversion (9.76%) compared to ICS 95 (7.34%). CCN 51 had the highest bean index (1.30) and the lowest pod index (22.0). This study demonstrated that structural pruning improved bean indexand pod index. We concluded that for CCN 51 by approximation grafting technique is a good alternative for a tropical dry forest, as its production between 1995 and 2277 kg of dry cocoa beans ha-1 year-1.

Soil contamination with permissible levels of lead negatively affects the community of plant-associated insects: A case of study with kale

This study investigated whether lead (Pb), at concentrations allowed for soil, affects the community of insects that live in the aerial part of plants. We evaluated the effect of Pb concentrations on accumulated species richness, composition, and abundance of different functional groups of insects. Kale plants were grown in soil experimentally contaminated with four concentrations of lead nitrate: 0 (control), 144 (T1), 360 (T2), and 600 (T3) mg/kg of soil. The experiment was conducted in an open greenhouse for the natural colonization of insects. Insects were collected twice using trap bags attached to the plant leaf and by direct removal. The concentration of Pb in the stem and leaf samples increased with the increased soil contamination, even showing values above the limit allowed by the legislation for this plant species. Control plants showed a higher richness of accumulated insect species. In addition, the treatments had an effect on the community composition, in which Diaeretiella rapae (primary parasitoid) was found as an indicator of the control + T1 treatments and the top species Pachyneuron sp. (parasitoid of predators) was associated with the control. The abundance of chewing and sucking herbivores, their respective parasitoids, predators, and parasitoids of predators were negatively affected. Hyperparasitoid abundance was not affected, but their accumulated species richness was. This study was innovative in demonstrating that soil contamination by different concentrations of a heavy metal (Pb) can negatively affect the community of plant-associated insects, even at concentrations allowed for soil, reflecting possible damage to the ecosystem.

Effect of shading and high temperature amplitude on yield and phenolic contents of greenhouse capsicum (Capsicum annuum L.)

Low temperature is one of the most important abiotic factor that restrict the optimal production of warm-season vegetables in the cold mountain regions. Studies were conducted to establish the possibility of growing capsicum, a temperature sensitive crop, in a naturally ventilated passive solar greenhouse with high temperature amplitude (25.2±2.5ºC). Despite the temperature fluctuation from 6.8±2.9°C at night to 38.6±4.1°C day temperature, flowering and fruiting were seen. The salable yield inside the greenhouse was 4.5 to 4.8-fold higher that of open field. Red shade net combine with the greenhouse technology significantly increased the intercellular CO2 concentration but affected the photosynthetic rate. Shading delayed flowering and 51-59% reduction in salable fruit yield. Total phenolic contents (TPC) and total flavonoid contents (TFC) of capsicum grown under open field and greenhouse were similar. However, shading reduced the TPC and TFC by 35.2% and 14.6%, respectively inside the greenhouse.

ANATOMICAL INVESTIGATIONS ON MOMORDICA CHARANTIA L. PLANTS, NEWLY ACCLIMATED IN ROMANIA

Momordica charantia L. (Cucurbitaceae family), medicinal and nutraceutical plant known from Asia, South Africa, South America, the Caribbean region, has been acclimatized in Romania since 1990 until now. This plant, cultivated in the open greenhouses belonging to S.C. HOFIGAL Import Export S.A. has been studied in several projects, among which “Project 160/2014-2017 – MAIA – Multifunctional and innovative products for safe and bioenhanced functional food from newly cultivated plants in Romania”, coordinated by ICECHIM/ INCDCP Bucharest. Starting from this project, a documentary study was carried out on the Momordica charantia plants acclimatized in different countries, and a morpho-anatomical research was initiated on the specimens grown in Romania, in the greenhouses belonging to S.C. HOFIGAL (Voucher BUC 408946-408950). The anatomical observations concerned the organization of the stem, petiole, and leaf lamina, using sets of cross-sectional and paradermal sections, treated with identification substances (IIK) and differential and successive stains (Iodine Green and Carmine Alum). Structural characteristics have been investigated under optical microscopy and documented through original photographic images and a set of dimensional data, data which are only partially found in the specialised literature. The results of our research are generally within the existent anatomical patterns. However, certain particular aspects have been noticed, regarding the epidermal cells, mechanical tissues, conducting tissues and mesophyll, completing the knowledge regarding the anatomy of acclimatized Momordica charantia plants.

Heat and Fluid Flow in an Open Agricultural Greenhouse in Presence of Plants

Flow convection in agriculture greenhouse is one of the most important factors on the growth and fruiting of plants. The present work focused on natural convection in an open greenhouse heated by ridge tubes in presence of plants. Analyses are performed for different boundary conditions imposed at the roof such as constant temperature, convective heat flux, and convective and radiative heat flux. The governing equations comprising continuity, momentum and energy equations are solved by Ansys-Fluent software. In each case, the average velocity and temperature of the air are determined. The obtained results are presented in terms velocity and temperature profiles. Isothermal lines and velocity vectors showed that by increasing the convective heat transfer coefficient, the average temperature and average airflow velocity decrease. The outcomes of this study help build greenhouses with dimensions and materials to suitable for the given external conditions.

Diversity of nematophagous fungi associated with vegetable crops in Northern Algeria

In Algeria, vegetable crops occupy an important cultivated area which accounts for 70% of the total arable land. The Sahel and coastal areas are particularly occupied by plasticulture due to favorable pedoclimatic conditions, which also allows the outbreak of various diseases and pests. Among the latter, the root-knot nematodes of the genus Meloidogyne are considered as one of the most important phytosanitary problems both in open fields and greenhouses. Biological control is a realistic alternative to replace or at least minimize the use of chemicals. The study of microflora is essential for targeting new biological agents for pest control. Two study stations belonging to Algiers are selected: Staoueli and Bordj el Kiffan. Between 2017 and 2018, soil samples were taken at random from a depth of 0 to 10 cm inside the greenhouses (treated soils) and outside the greenhouses (no treatment). The results obtained revealed a diversity of species of nematophagous fungi belonging to 8 genera, Arthrobotrys, Dactylaria, Dactylella, Myzocytium, Harposporium, Rhopalomyces, Stylopage and Triposporina. The most frequent species is Arthorobotrys musiformis with a rate of 77.5% in untreated Bordj-el-kiffan soils and 57.5% in treated soils, Staouali has a percentage of 55% and 57.5% in treated and untreated soils respectively. This study give new insights regarding the availability of endemic nematophagous fungi vegetables fields. Parasitism assessment indicated that 8 nematophagous fungi were efficient to suppress M. incognita and M. javanica by 70% and 50%, respectively. This indicate their potential as biocontrol agents against plant parasitic nematodes.

Long-Term Potato Virus X (PVX)-Based Transient Expression of Recombinant GFP Protein in Nicotiana benthamiana Culture In Vitro.

Simple SummaryNowadays, the global recombinant protein market is valued at USD 125 billion. While the main producers of recombinant proteins are bacterial and mammalian cell cultures, plants have been intensively explored as an alternative platform for obtaining recombinant proteins (biopharming). Plants are safer systems, as they are free of human pathogens, oncogenic sequences, or bacterial endotoxins. Here, we proposed a new system for the production of recombinant proteins through transient expression technology in Nicotiana benthamiana plants grown in aseptic conditions (in vitro). Closed in vitro systems (cell tissue cultures) are well controlled; thus, they are preferable for recombinant protein production, as they can be more easily standardized for the pharmaceutical market purposes, and transient expression allows high levels of the recombinant proteins to be produced. We used an agrobacteria-delivered vector containing phytopathogenic virus (potato virus X) sequences to create plant tissue culture with prolongated transient expression of recombinant reporter green fluorescent protein (GFP). The mean of GFP was 18% of the total soluble cell proteins (TSP) (0.52 mg/g of fresh leaf weight (FW), and the best result reached 47% TSP (2 mg/g FW). The system can be a new technique for biopharming, combining the advantages of transient expression and cell tissue cultures.Plant molecular farming has a great potential to produce valuable proteins. Transient expression technology provides high yields of recombinant proteins in greenhouse-grown plants, but every plant must be artificially agroinfiltrated, and open greenhouse systems are less controlled. Here, we propose to propagate agrobacteria-free plants with high-efficient long-term self-replicated transient gene expression in a well-controlled closed in vitro system. Nicotiana benthamiana plant tissue culture in vitro, with transient expression of recombinant GFP, was obtained through shoot induction from leaf explants infected by a PVX-based vector. The transient expression occurs in new tissues and regenerants due to the natural systemic distribution of viral RNA carrying the target gene. Gene silencing was delayed in plants grown in vitro, and GFP was detected in plants for five to six months. Agrobacteria-free, GFP-expressing plants can be micropropagated in vitro (avoiding an agroinfiltration step), “rejuvenated” through regeneration (maintaining culture for years), or transferred in soil. The mean GFP in the regenerants was 18% of the total soluble proteins (TSP) (0.52 mg/g of fresh leaf weight (FW). The highest value reached 47% TSP (2 mg/g FW). This study proposes a new method for recombinant protein production combining the advantages of transient expression technology and closed cultural systems.

Evaluation of ultrasonic parameters as a non-invasive, rapid and in-field indicator of water stress in Citrus plants

Non-Contact Resonant Ultrasound Spectroscopy (NC-RUS) has emerged as a powerful tool to determine plant water status in a non-destructive, non-invasive and rapid way. In this study, ultrasonic parameters directly obtained from experimental measurements in the field using NC-RUS - such as resonant frequency (fres), velocity (v) and Q-factor - were evaluated as potential water stress indicators in Citrus plants. The experiments were carried out in two-year-old mandarin trees (Citrus clementina Hort. ex Tan. ‘Clemenules’) grown in pots in an open greenhouse where two different groups of plants were tested: a Control group (full irrigation) and a Drought Stress group (DS) whose irrigation was withdrawn during 7 days, followed by a 16 days recovery period. Soil water content, leaf water potential (Ψleaf) and the considered ultrasonic parameters were measured in the same leaves. fres detected changes between control and DS at day 7 without irrigation. Conversely, v showed differences after day 3, which were statistically significant at day 7, enabling discrimination between C and DS groups. Hence, Q-factor was the ultrasonic parameter that showed statistically significant differences between C and DS groups at days 3 and 7. Consequently, Signal Intensity in Q during the drought treatment showed a similar evolution to Ψleaf, although with slightly lower performance. However, Q-factor sensitivity excels Ψleaf at each day studied. Finally, a linear correlation (R2=0.57) between Ψleaf and Q-factor of all experimental data measured in DS group plants along the drought treatment was found. In conclusion, the ultrasonic parameters obtained using NC-RUS and in particular the Q-factor, demonstrated to be potential new water stress indicators in Citrus trees, with the novelty of being non-destructive, non-invasive and rapid. Future work should explore its suitability for its use in irrigation scheduling for Citrus trees.