An automated system for controlling drought stress and irrigation in potted plants

Efficient, automated irrigation systems, which can irrigate the substrate of potted plants to a desired level and supply those plants with just the amount of water required for normal plant growth are currently not available. These systems, if developed, could reduce wastage of irrigation water due to excess application. This subsequently could reduce leaching and run-off, and aid growers to cope with increasing regulations of water-use by state governments in the US. Here we describe an irrigation controller that irrigates a substrate to a set-point (volumetric water content, θ) and maintains θ close to that set-point for several weeks. The controller uses calibrated, dielectric moisture sensors, interfaced with a datalogger and solenoid valves, to measure the θ of the substrate every 20 min. When the θ of the substrate drops below the set-point, the controller opens a solenoid valve, which results in irrigation. The θ of the substrate is maintained near a constant level as the datalogger is programmed to increase θ by only 2–3% during each irrigation. Using this controller with bedding plants, we were able to maintain four distinct levels of θ for a prolonged period (40 days), regardless of changes in plant size and environmental conditions. The daily average θ maintained was slightly higher (within 2–3% on any particular day) than the set-point. When the θ measured and maintained by the dielectric moisture sensors was tested using measurements with another probe placed in the same container, the θ measured by both probes was found to be similar, indicating that the controller can indeed maintain θ near the target level. This controller may also have applications in stress physiology, since it allows control over the rate at which drought stress is imposed on plants.     

A whole-plant, open, gas-exchange system for measuring net photosynthesis of potted woody plants

Chambers were constructed to measure gas exchange of entire potted grapevines (Vitis vinifera L.). The plant enclosures were constructed from Mylar film, which is nearly transparent to photosynthetically active radiation. Maintaining a slight, positive, internal pressure allowed the Mylar chambers to inflate like balloons and required no other means of support. The whole-plant, gas-exchange chamber design and construction were simple and inexpensive. They were assembled easily, equilibrated quickly, and did not require cooling. They allowed for the measurement of any plants in a relatively short period. This system would enable the researcher to make replicated comparisons of treatment influences on whole-plant CO2 assimilation throughout the growing season. While CO2 measurement was the focus of this project, it would be possible to measure whole-plant transpiration with this system.     

Response of gladiolus (Gladiolus spp) plants after exposure corms to chitosan and hot water treatments

The state of Morelos, Mexico has gradually become an important producer of gladiolus. Some preconditioning treatments of corms are empirically done causing uneven emergence and low quality of flowers. In this investigation, before planting, gladiolus corms var. ‘Blanca Borrego’ were dipped in chitosan (chitosan reagent and commercial chitosan Biorend^®), in hot water at various temperatures and in treatments combined with Biorend^® at 1.5% and hot water. Results indicated that the most influenced variables were corm germination, number of flowers per spike, number of cormlets and vase life. Overall, the commercial product Biorend^® at 1.5% accelerated corm emergence in approximately 4 days, the number of flowers increased by 2–7 and the vase life extended for 3 days. The number of cormlets was also duplicated. Corms dipped in the commercial chitosan Biorend^® at 1.5% at different intervals of time were not greatly affected except for the emergence and number of cormlets. However, for this experiment there were significant effects on the number of leaves and flowers because of the interactions between chitosan and the immersion time. The temperature of 55 °C affected plant development because emergence was delayed by 6 days; and there were less number of leaves, flowers and cormlets. On the other hand, the incidence of Fusarium oxysporum in naturally infected corms was 0% at temperatures of 55 °C and 50 °C. Immersion times (0, 10, 15 and 20 min) in hot water at 50 °C did not show significant effects on plant development and vase life. Corms dipped in Biorend^® at 1.5% and hot water at 50 °C accelerated their emergence for about 1–7 days, the number of flowers increased by two, extended the storage life for 1–3 days and increased the number of cormlets. The integration of these two treatments -Biorend^® and hot water- might be a good option for increasing the gladiolus plant quality and vase life.     

A sterile hydroponic system for characterising root exudates from specific root types and whole-root systems of large crop plants

Background

Plant roots release a variety of organic compounds into the soil which alter the physical, chemical and biological properties of the rhizosphere. Root exudates are technically challenging to measure in soil because roots are difficult to access and exudates can be bound by minerals or consumed by microorganisms. Exudates are easier to measure with hydroponically-grown plants but, even here, simple compounds such as sugars and organic acids can be rapidly assimilated by microorganisms. Sterile hydroponic systems avoid this shortcoming but it is very difficult to maintain sterility for long periods especially for larger crop species. As a consequence, studies often use small model species such as Arabidopsis to measure exudates or use seedlings of crop plants which only have immature roots systems.

Results

We developed a simple hydroponic system for cultivating large crop plants in sterile conditions for more than 30 days. Using this system wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) plants were grown in sterile conditions for 30 days by which time they had reached the six-leaf stage and developed mature root systems with seminal, nodal and lateral roots. To demonstrate the utility of this system we characterized the aluminium-activated exudation of malate from the major types of wheat roots for the first time. We found that all root types measured released malate but the amounts were two-fold greater from the seminal and nodal axile roots compared with the lateral roots. Additionally, we showed that this sterile growth system could be used to collect exudates from intact whole root systems of barley.

Conclusions

We developed a simple hydroponic system that enables cereal plants to be grown in sterile conditions for longer periods than previously recorded. Using this system we measured, for the first time, the aluminium-activated efflux of malate from the major types of wheat roots. We showed the system can also be used for collecting exudates from intact root systems of 30-day-old barley plants. This hydroponic system can be modified for various purposes. Importantly it enables the study of exudates from crop species with mature root systems.

     

Light-emitting diodes as a radiation source for plants

Development of a more effective radiation source for use in plant-growing facilities would be of significant benefit for both research and commercial crop production applications. An array of light-emitting diodes (LEDs) that produce red radiation, supplemented with a photosynthetic photon flux (PPF) of 30 micromoles s-1 m-2 in the 400- to 500-nm spectral range from blue fluorescent lamps, was used effectively as a radiation source for growing plants. Growth of lettuce (Lactuca sativa L. Grand Rapids') plants maintained under the LED irradiation system at a total PPF of 325 micromoles s-1 m-2 for 21 days was equivalent to that reported in the literature for plants grown for the same time under cool-white fluorescent and incandescent radiation sources. Characteristics of the plants, such as leaf shape, color, and texture, were not different from those found with plants grown under cool-white fluorescent lamps. Estimations of the electrical energy conversion efficiency of a LED system for plant irradiation suggest that it may be as much as twice that published for fluorescent systems.     

A regulation-oriented approach for allergenicity categorization of plants

Plant species have different degrees of allergenicity. Existing systems categorizing plants according their allergenicity were reviewed to find a method that could serve as the basis for the regulation of green areas. The categorization of plants by their allergenicity serves different purposes: informing allergic patients, warning consumers in horticultural stands, or evaluating urban green areas. The regulation of allergenic plants in trade and their use in urban greening is a new, emerging application of allergenic categorization. Our review showed that the existing systems cannot be used for this purpose, because they cannot fulfill the main requirements of regulation: the methods were often not described, and this affected reproducibility and there was a lack of evidence on allergenicity. To overcome these issues, a new, evidence-based categorization (CARE-S) was developed using genetically determined factors of plants: immunogenicity, morphology, and pollen production. 529 plant taxa were categorized, mostly those common in urban areas in the Pannonian Biogeographical Region. The new system can be applied in other biogeographic areas and on new plant varieties by an online calculator tool. An adaptation strategy of CARE-S in regulations is also proposed. Additional benefits of CARE-S: 1: promoting the development of low-allergenic cultivars, 2: identifying overlooked allergens, recommending their use in clinical tests, 3: calling attention to plant taxa which need more research in allergology or botany; 4: providing a legal tool to prevent the introduction and dispersal of (new) allergenic plants. As a further step the authors suggest developing another tool, epidemiological allergenicity, derivated from CARE-S, aiming to characterize the geographically-determined effects of plants on human populations.     

An integrated method for irrigation scheduling of potted plants

Hourly meteorological and soil water potential data collected during the summer season on a container crop of 2-year-old plants of Hypericum hidcote were used to develop a methodology that integrates climate-based (AET = ETo × K_c) and soil-based methods (soil water potential measurements by tensiometers) for the automatic control of the irrigation of plants growing in pots. Hourly ETo values were calculated by the CIMIS equation, derived from the Penman formula. Tensiometric data, by a soil-specific tensiometric curve, were transformed into pot water weight and used to estimate actual hourly evapotranspiration (AETt).     

An efficient immunodetection method for histone modifications in plants

Background

Epigenetic mechanisms can be highly dynamic, but the cross-talk among them and with the genome is still poorly understood. Many of these mechanisms work at different places in the cell and at different times of organism development. Covalent histone modifications are one of the most complex and studied epigenetic mechanisms involved in cellular reprogramming and development in plants. Therefore, the knowledge of the spatial distribution of histone methylation in different tissues is important to understand their behavior on specific cells.

Results

Based on the importance of epigenetic marks for biology, we present a simplified, inexpensive and efficient protocol for in situ immunolocalization on different tissues such as flowers, buds, callus, somatic embryo and meristematic tissue from several plants of agronomical and biological importance. Here, we fully describe all the steps to perform the localization of histone modifications. Using this method, we were able to visualize the distribution of H3K4me3 and H3K9me2 without loss of histological integrity of tissues from several plants, including Agave tequilana, Capsicum chinense, Coffea canephora and Cedrela odorata, as well as Arabidopsis thaliana.

Conclusions

There are many protocols to study chromatin modifications; however, most of them are expensive, difficult and require sophisticated equipment. Here, we provide an efficient protocol for in situ localization of histone methylation that dispenses with the use of expensive and sensitive enzymes. The present method can be used to investigate the cellular distribution and localization of a wide array of proteins, which could help to clarify the biological role that they play at specific times and places in different tissues of various plant species.

     

An evaluation of pre-emergent herbicides for container-grown ornamental plants

Two applications of 5 herbicides were evaluated during spring and summer for weed control and phytotoxicity on 25 species of trees, shrubs and herbaceous perennials. Weed control was considered to be effective if herbicide-treated pots contained at most 20% of the weeds in untreated pots. Oxyfluorfen applied at 1.25, 2.5 and 5.0 kg ha^?1 provided effective control of grass and broad-leaved weeds for 8 weeks after the first application, and the 2 higher rates effectively controlled all weeds for 12 weeks after the second application. Oxadiazon at 2.0, 4.0 and 8.0 kg ha^?1 effectively controlled all weeds for 8 weeks after the first application, but only the highest rate was effective 12 weeks after the second application. Napropamide at 5.0, 10.0 and 20.0 kg ha^?1 effectively controlled grasses for up to 12 weeks, but only effectively controlled broad-leaved weeds at the 2 higher rates for 8 weeks after the first application and failed to control them after the second application. Alachlor at 4.0, 8.0 and 16.0 kg ha^?1 and oryzalin + trifluralin at 0.5, 1.0 and 2.0 kg ha^?1 provided effective control of grasses for 8 weeks after the first application. These herbicides at the highest rate also controlled broad-leaved weeds for 8 weeks after the first application. However alachlor and oryzalin + trifluralin failed to provide effective control of any weeds after the second application.Competition from weeds reduced the shoot dry weight (SDW) of unweeded control pots by 20% compared with hand-weeded control pots. None of the herbicides produced visible clamage in any plants. The SDW of 8 species treated with some of the herbicides was significantly lower than the corresponding hand-weeded control plants, and for 6 of these species some herbicide treatments were identified as being possibly phytotoxic. Oxyfluorfen appeared to inhibit the growth of Photinia and Coleonema, and alachlor inhibited the growth of Photinia, Eriostemon, Azalea ‘Splendens’, Lavendula and Coleonema. Oryzalin + trifluralin appeared to inhibit the growth of Bauhinia, and napropamide and oxadiazon inhibited the growth of Coleonema.     

A novel fluorescent pH probe for expression in plants

Background  

The pH is an important parameter controlling many metabolic and signalling pathways in living cells. Recombinant fluorescent pH indicators (pHluorins) have come into vogue for monitoring cellular pH. They are derived from the most popular Aequorea victoria GFP (Av-GFP). Here, we present a novel fluorescent pH reporter protein from the orange seapen Ptilosarcus gurneyi (Pt-GFP) and compare its properties with pHluorins for expression and use in plants.     

A faster inoculation assay for Armillaria using herbaceous plants

Armillaria (honey fungus) is a virulent necrotrophic pathogen that causes Armillaria root disease. Conventional Armillaria inoculation assays use young saplings as hosts and consequently are cumbersome, frequently conducted outdoors, and take many years from establishment to analysis of infection. We have developed and evaluated a faster inoculation assay for Armillaria that uses herbaceous plants as hosts, is carried out in controlled conditions, and reduces experimental durations to 3 months. Plant species of known susceptibility to Armillaria and comparisons between virulent A. mellea and opportunistic A. gallica were used to validate the assay. Mortality and diagnostic symptoms of Armillaria root disease such as epiphytic rhizomorphs and mycelial fans were used to assess levels of infection. We also attempted to reduce assay preparation time by substituting woody inocula with agar inocula, but typical symptoms of Armillaria root disease were only observed on plants infected with woody inocula. Through our assay, we identified five new potential herbaceous hosts of Armillaria: Kniphofia hirsuta, Hordeum vulgare, Lobelia cardinalis, Nicotiana tabacum and Helenium hoopesii – further expanding the extensive list of plants with susceptibility to Armillaria and suggesting infection of herbaceous species may be more widespread than currently acknowledged.     

A high-throughput seed germination assay for root parasitic plants

Background

Some root-parasitic plants belonging to the Orobanche, Phelipanche or Striga genus represent one of the most destructive and intractable weed problems to agricultural production in both developed and developing countries. Compared with most of the other weeds, parasitic weeds are difficult to control by conventional methods because of their life style. The main difficulties that currently limit the development of successful control methods are the ability of the parasite to produce a tremendous number of tiny seeds that may remain viable in the soil for more than 15 years. Seed germination requires induction by stimulants present in root exudates of host plants. Researches performed on these minute seeds are until now tedious and time-consuming because germination rate is usually evaluated in Petri-dish by counting germinated seeds under a binocular microscope.

Results

We developed an easy and fast method for germination rate determination based on a standardized 96-well plate test coupled with spectrophotometric reading of tetrazolium salt (MTT) reduction. We adapted the Mosmann’s protocol for cell cultures to germinating seeds and determined the conditions of seed stimulation and germination, MTT staining and formazan salt solubilization required to obtain a linear relationship between absorbance and germination rate. Dose–response analyses were presented as applications of interest for assessing half maximal effective or inhibitory concentrations of germination stimulants (strigolactones) or inhibitors (ABA), respectively, using four parameter logistic curves.

Conclusion

The developed MTT system is simple and accurate. It yields reproducible results for germination bioassays of parasitic plant seeds. This method is adapted to high-throughput screenings of allelochemicals (stimulants, inhibitors) or biological extracts on parasitic plant seed germination, and strengthens the investigations of distinctive features of parasitic plant germination.

     

离子注入对百合基因转化受体系统建立的影响

以兰州百合为研究对象,通过鳞片离体培养、抗生素筛选以及离子束处理等,建立了稳定高效的基因转化受体系统。结果表明:MS 6-BA1.0mg/L NAA0.5mg/L是不定芽诱导的适宜培养基,1/2MS NAA0.2mg/L 0.1%活性炭是较为适宜的生根壮苗培养基。抗生素敏感性试验表明,卡那霉素和头孢霉素选择压分别以125mg/L和300mg/L较为适宜。运用能量为30keV的低能氮离子束注入百合鳞片,发现8×10~(14)N /cm~2的剂量对不定芽的诱导具有明显的刺激和促进作用。     

Protective effects and mechanism of heat shock response on cardiovascular system in rats after heat exposure

AIM:To study protective effects and mechanism of heat shock response (HSR) on cardiovascular system in rats after heat exposure.METHODS:The study was divided into 2 experiments:①Protective effects of HSR on cardiovascular system in rats after heat exposure.SD rats randomly allocated into 2 groups:heat shock group (HS group), sham control group(SC group).HS group were treated with heat shock, but SC group weren't.After re-covering for 20 h at room temperature, two groups exposed to death in thermal environment, and blood pressure and elec-trocardiogram were measured continuously.Through Chart software mean arterial pressure(MAP), existent time etc were acquired.②SD male rats randomly allocated into 3 groups:HS group, SC group and normal temperature control group(NC group).NC group weren't treated.The treatment in HS and SC group was identical with in the first experiment, but it would be terminated at 73 min after heat exposure, meanwhile content of MDA of myocardium were measured.RESULTS:① Existent time in HS group was longer than that in SC group and shock arrived later; ② During earlier period after heat exposure MAP had no significant changes between HS and SC group, but after 60 mins MAP in HS group were higher than that in SC group; ③ Compared with NC group, content of MDA in myocardium in SC group was higher significantly at 73 min after heat exposure. Howerer, content of MDA in HS group was lower than in SC group, and had no significant changes with NC group.CONCLUSION:Through decreasing production of MDA in myocardium, HSR has a protective effect on cardiovascular system in rats after heat exposure.     

空气凤梨对气体污染物的监测和修复

空气凤梨是一类生长在空气中、不需要土壤的特殊植物。其生长所需的水分和营养可以全部来自空气,因此也能够同时吸附或吸收大气降尘中的污染物(包括有机污染物及重金属污染物),从而成为有效的监测环境变化的指示生物和去除环境污染的修复植物。文章综述了空气凤梨的生物学特征,以及对环境污染的响应机制。     

我国园艺作物核心种质研究进展

综述了我国园艺植物核心种质研究进展,针对目前园艺作物核心种质研究现状与问题,提出了今后园艺作物核心种质研究方向,即要加强对取样策略、分组原则等问题的研究,加速收集园艺作物种质资源的基础数据、特征数据、评价鉴定数据及分子检测数据,尽快建立一批我国原产的、重要的园艺作物的核心种质,以提高园艺作物种质资源利用效率,提升种质创新能力,从而推动我国园艺产业快速发展。     

UV-B radiation and photosynthetic irradiance acclimate eggplant for outdoor exposure

Treatment of greenhouse-grown eggplant (Solanum melongena L. var. esculentum Nees. 'Burpee's Black Beauty') seedlings with supplemental photosynthetically active radiation from cool-white fluorescent lamps increased growth of plants subsequently transferred outdoors relative to growth of plants that received no supplemental radiation or were shaded to 45% of solar irradiation in the greenhouse before transfer outdoors. Eggplant seedlings transferred outdoors were placed under plastic tarps either to provide relative protection from solar ultraviolet-B (UV-B) radiation (280-315 nm) using Mylar film or to allow exposure to UV-B using cellulose acetate. Protection of seedlings from UV-B radiation resulted in greater leaf expansion than for UV-B-exposed seedlings, but no change in leaf or shoot dry weight occurred after 9 days of treatment. Specific leaf weight increased in response to UV-B exposure outdoors. Exposure of eggplant to UV-B radiation from fluorescent sunlamps in the greenhouse also decreased leaf expansion and leaf and shoot dry weight gain after 5 days of treatment. However, there were no differences in leaf or shoot dry weight relative to control plants after 12 days of UV-B treatment, indicating that UV-B treated plants had acclimated to the treatment and actually had caught up with non-UV-B-irradiated plants in terms of growth.     

A modified Gateway cloning strategy for overexpressing tagged proteins in plants

Background  

Recent developments, including the sequencing of a number of plant genomes, have greatly increased the amount of data available to scientists and has enabled high throughput investigations where many genes are investigated simultaneously. To perform these studies, recombinational cloning methods such as the Gateway system have been adapted to plant transformation vectors to facilitate the creation of overexpression, tagging and silencing vectors on a large scale.