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Satureja hortensis L. (summer savory) is among the most important medicinal plants, grown in different parts of the world including Iran. The objective was to enhance the morphological properties of different genotypes of summer savory in temperature (warm, mild and cold) stress by fertilization and plant growth regulators (PGRs), as it has not been previously investigated, to our knowledge. The effects of fertilization (F1) (MI, 2 g L−1), and PGRs (sprayed four times during the season) including amino acid (F2) (A, 2 g L−1), gibberellic acid (F3) (GA, 2 mM), and control (F4) (using water) were examined on plant growth. The summer savory genotypes (Khuzestani, Mutika and Bakhtiari) were planted on the 8th of April (13.0 °C), May (20.8 °C), and June (26.0 °C), and a wide range of plant growth parameters were determined. Genotype Mutika was the most responsive one with significantly higher growth under all temperature conditions. Even under the cold stress Mutika root fresh weight was significantly higher than that of the other genotypes. However, fertilization and PGRs significantly increased the fresh weight of aerial part in all genotypes. All treatments significantly increased the flower number in cold stress. MI, compared with the PGRs, significantly increased side stem height, in different temperatures. The highest effects of treatments were observed on root volume, aerial part and total fresh weights, stem height and flower number. It is possible to plant and improve S. hortenesis morphological properties in different climatic conditions using the tested treatments and the appropriate genotype affecting plant physiological metabolisms. [Display omitted] • S. hortensis growth affected by genotype, cold, fertilization and plant growth regulators. • Root fresh weight of stressed Mutika was significantly higher than the other genotypes. • Biochemicals significantly increased aerial fresh weight in all genotypes. • Genotype Mutika was the most responsive one with significantly higher growth. • The use of proper genotype treated with biochemicals is recommendable under stress. [ABSTRACT FROM AUTHOR]

During plant–pathogen interactions, the plant cell wall forms part of active defence against invaders. In recent years, cell wall-editing enzymes, associated with growth and development, have been related to plant susceptibility or resistance. Our previous work identified a role for several tomato and Arabidopsis endo-1,4-β-glucanases (EGs) in plant–pathogen interactions. Here we studied the response of the Arabidopsis thaliana T-DNA insertion mutant lacking EG Korrigan1 (KOR1) infected with Pseudomonas syringae . KOR1 is predicted to be an EG which is thought to participate in cellulose biosynthesis. We found that kor1-1 plants were more susceptible to P. syringae , and displayed severe disease symptoms and enhanced bacterial growth if compared to Wassilewskija (Ws) wild-type plants. Hormonal and gene expression analyses revealed that the jasmonic acid (JA) pathway was activated more in kor1-1 plants with an increase in the JA-biosynthesis gene LOX3 and a greater accumulation of JA. Upon infection the accumulation of JA and JA-isoleucine (JA-Ile) was higher than in wild-type plants and increased the induction of LOX3 and the JA-responsive PDF1.2 gene. In addition, the increase of salicylic acid (SA) in healthy and infected kor1-1 may reflect the complex interaction between JA and SA, which results in the more susceptible phenotype displayed by the infected mutant plants. Callose deposition was enhanced in infected kor1-1 and an increase in pathogen-induced hydrogen peroxide took place. The susceptible phenotype displayed by KOR1-deficient plants was coronatine-independent. No significant changes were detected in the hormonal profile of the kor1-1 plants infected by coronatine-deficient P. syringae cmaA , which supports that absence of EG KOR1 alters per se the plant response to infection. We previously reported increased resistance of kor1-1 to B. cinerea , hence, the lack of this EG alters cell wall properties and plant responses in such a way that benefits P. syringae colonisation but restricts B. cinerea invasion. [ABSTRACT FROM AUTHOR]

Precision agriculture (PA) technologies allow us to assess field variability and support site-specific (SSP) application of inputs. The joint application of PA and organic farming practices might be synergetic. The objective of this 3-year study was to propose a multivariate statistical and geostatistical approach, to evaluate the effects of SSP nitrogen (N) fertilization on durum wheat in transition to organic farming. Soil parameters were measured to assess soil fertility level before the SSP fertilization on wheat, which was carried out by management zones in the third year. Radiometric measurements were performed with a hyperspectral spectroradiometer and N-uptake at anthesis and grain yield were determined. The expected values and 95 % confidence intervals of the soil parameters, N-uptake and yield data were estimated with polygon kriging for each management zone. Reflectance data were reduced through principal component analysis and the retained principal components were submitted to factorial co-kriging analysis to estimate orthogonal scale-dependent factors. Comparisons between N-uptake and yield and between the retained regionalized factors (F1) and yield were performed. The spatial pattern of F1 at shorter scales was mostly reproduced in the N-uptake map, suggesting the predictive capacity of hyperspectral data for crop N-status. Within-cluster variance for yield was reduced, quite probably as a combined effect of meteorological pattern and management. The preliminary results seem to be promising in the perspective of PA. Moreover, an inverse relationship between grain yield and crop N-status was observed. [ABSTRACT FROM AUTHOR]

Changes in stem sugar concentrations due to drought stress at the early reproductive stage were studied in seven sorghum (Sorghum bicolor (L.) Moench) genotypes that differ in their stem sugar storage ability. Total sap sugar concentration increased in most genotypes. ANOVA showed a significant contribution of genotype and treatment to the variation in sugar levels. Two genotypes showed little variation in total sugar levels at the fifth internode from the peduncle and five genotypes showed significant increases in total sugar levels under drought; these groups were used to compare sugar metabolism. Drought led to a decrease in catabolic sucrose synthase activity in both groups. Invertase activities increased significantly in two genotypes and correlated with the increase in reducing sugar concentrations under drought. Stem sugar hydrolysis probably had a role in osmotic adjustment under drought and correlated with retention of sap volume. However, the activities of sugar-metabolising enzymes did not correlate with their gene expression levels. After resuming irrigation, grain yields, stalk yields and juice volume at physiological maturity were lower in plants recovering from drought stress compared with the controls. In some genotypes, there were similar losses in grain yields and stem sugars due to drought, indicating photoassimilate source limitation; in other genotypes, grain yield losses were less than stem sugar losses in drought-exposed plants compared with the controls, suggesting mobilisation of sugars from the storage internodes to the developing panicle. Accumulation of stem sugars appears to be an adaptive strategy against drought stress in some sorghum genotypes. [ABSTRACT FROM AUTHOR]

Anthropogenic disturbances in wetland ecosystems can alter the composition and structure of plant assemblages and affect system functions. Extensive oil and gas extraction has occurred in wetland habitats along the northern Gulf of Mexico coast since the early 1900s. Activities involved with three-dimensional (3D) seismic exploration for these resources cause various disturbances to vegetation and soils. We documented the impact of a 3D seismic survey in coastal marshes in Louisiana, USA, along transects established before exploration began. Two semi-impounded marshes dominated by Spartina patens were in the area surveyed. Vegetation, soil, and water physicochemical data were collected before the survey, about 6 weeks following its completion, and every 3 months thereafter for 2 years. Soil cores for seed bank emergence experiments were also collected. Maximum vegetation height at impact sites was reduced in both marshes 6 weeks following the survey. In one marsh, total vegetation cover was also reduced, and dead vegetation cover increased, at impact sites 6 weeks after the survey. These effects, however, did not persist 3 months later. No effects on soil or water properties were identified. The total number of seeds that germinated during greenhouse studies increased at impact sites 5 months following the survey in both marshes. Although some seed bank effects persisted 1 year, these effects were not reflected in standing vegetation. The marshes studied were therefore resilient to the impacts resulting from 3D seismic exploration because vegetation responses were short term in that they could not be identified a few months following survey completion. [ABSTRACT FROM AUTHOR]

The impact of heterogeneous soil compaction in combination with nutrient availability on root system architecture and root growth dynamics has scarcely been investigated. We quantified changes of barley (Hordeum vulgare L.) root and shoot growth during the first 3 weeks of growth in a controlled-environment chamber. Vertically divided split-root rhizotrons were filled either uniformly with loose or compacted peat, or heterogeneously with loose peat in one compartment and compacted peat in the other. We investigated the following questions. (a) Can growth processes affected by soil compaction be mimicked in our system? (b) Do plants show compensatory growth effects when exposed to heterogeneous soil compaction? (c) Does localised fertiliser application affect root systems' responses to compaction? We observed compensatory effects regarding root system architecture and root growth dynamics due to vertically heterogeneous soil compaction. Roots grew deeper and lateral roots emerged earlier in the loose compartment of the split-root treatment compared with uniform treatments. When fertiliser was applied only via the compacted compartment in the split-root treatment, more lateral roots were initiated in the compacted compartment and lateral root formation started a few days earlier than in the uniform treatments. Consequently, the first days after exposure to heterogeneous soil conditions are critical for the analysis of underlying physiological responses. The effects of localised soil compaction plus nutrient availability on root system architecture (RSA) and root growth dynamics have scarcely been investigated. We investigated the impact of heterogeneous soil conditions on barley RSA, and root and shoot growth using split-root rhizotrons, and observed dynamic compensatory alterations, particularly in lateral root initiation. In loose compartments formation of lateral roots started earlier than in uniform treatments and was significantly increased in compacted compartments when only these compartments were fertilised. [ABSTRACT FROM AUTHOR]

The responses of two closely related members of Arabidopsis 13-lipoxygenases (13- LOXs), LOX3 and LOX4, to infection by the sedentary nematodes root-knot nematode ( Meloidogyne javanica) and cyst nematode ( Heterodera schachtii) were analysed in transgenic Arabidopsis seedlings. The tissue localization of LOX3 and LOX4 gene expression using β-glucuronidase ( GUS) reporter gene constructs showed local induction of LOX3 expression when second-stage juveniles reached the vascular bundle and during the early stages of plant-nematode interaction through gall and syncytia formation. Thin sections of nematode-infested knots indicated LOX3 expression in mature giant cells, and high expression in neighbouring cells and those surrounding the female body. LOX4 promoter was also activated by nematode infection, although the GUS signal weakened as infection and disease progressed. Homozygous insertion mutants lacking LOX3 were less susceptible than wild-type plants to root-knot nematode infection, as reflected by a decrease in female counts. Conversely, deficiency in LOX4 function led to a marked increase in females and egg mass number and in the female to male ratio of M. javanica and H. schachtii, respectively. The susceptibility of lox4 mutants was accompanied by increased expression of allene oxide synthase, allene oxide cyclase and ethylene-responsive transcription factor 4, and the accumulation of jasmonic acid, measured in the roots of lox4 mutants. This response was not found in lox3 mutants. Taken together, our results reveal that LOX4 and LOX3 interfere differentially with distinct metabolic and signalling pathways, and that LOX4 plays a major role in controlling plant defence against nematode infection. [ABSTRACT FROM AUTHOR]

In tomato, the stolbur disease caused by ' Candidatus Phytoplasma solani' alters developmental processes resulting in malformations of both vegetative and reproductive organs, two stolbur phytoplasma strains PO and C induce mutually distinct symptoms. The aim of the present study was to determine the effect of stolbur phytoplasma-infection on the Salicylic (SA) and Jasmonic (JA) acids hormone signalling pathways and to assess whether pre-activation of these defence pathways could protect tomato against the stolbur disease development. Expression of SA- and JA-dependent marker genes was studied in tomato by qRT-PCR. Results indicated that the SA-mediated defence response was activated by the stolbur phytoplasma strains PO and C in contrast to the JA-dependent defence pathway which was repressed by strain PO but activated by strain C. The two stolbur strains, PO and C, generated different responses, suggesting that the two strains might have distinct virulence factors, in agreement with the fact that they induce distinctive symptoms. In stolbur PO-infected tomato, pre-activation of the JA-dependent defence pathway by methyl jasmonate (MeJA) before infection had no effect on the disease development whereas pre-activation of the SA-dependent defence pathway by treatment with benzothiadiazole (BTH) prior to graft-inoculation of the phytoplasma resulted in a minor delay in phytoplasma multiplication and symptom production. As grafting implicates a high inoculum as compared to insect inoculation, it would be of interest to test BTH treatment in natural conditions. [ABSTRACT FROM AUTHOR]

Highlights: [•] We review current understanding of plant responses to climate extremes. [•] Various mechanisms underlying plant responses to climate extremes are summarized. [•] We propose future research effort in extreme event research. [Copyright &y& Elsevier]

Flash drought is an extreme phenomenon, characterized by unusually rapid intensification of drought severity, with strong impacts on plant growth especially for crops. However, it's unclear how hydrometeorological changes contribute to flash drought and how vegetation physiology, greenness, and productivity respond to flash drought. In this study, we developed an multivariate integrated framework for flash drought identification using a regression model based on principal-components analysis (PCA): the PCA regression flash drought (PRFD) model. Three criteria are specified to emphasize the rapid intensification of drought and its impacts on vegetation growth and water resources. We applied our new model in two geographical units with different climates and hydrology: one is dominated by agriculture and subject to natural drought (the Loess Plateau) and the other, a natural region with infrequent drought (the Qinling Mountains). We found that high frequency of flash droughts is most likely to occur in the eastern and central Loess Plateau and part of the Qinling Mountains. However, in relatively humid areas, flash drought shows strong intensity such as the Qinling Mountains and western and eastern edges of the Loess Plateau. Trend analysis indicates that PRFD has increased frequency, longer duration, and stronger intensity since the 1990s in both regions. From an ecological perspective, PRFD also showed a spatial pattern consistent with values of vegetation-related proxies that were below the long-term average, demonstrating vegetation transpiration, normalized-difference vegetation index (NDVI), gross primary productivity have obvious feedback on flash drought events. The Loess Plateau's NDVI responded immediately to flash drought, versus a 1-month lag in the Qinling Mountains. Because our proposed framework integrates multiple aspects of drought information, it can be applied in areas outside the study region according to regional hydrometeorological conditions. This has significant implications for improving agricultural management and forecasting future severe impacts of flash drought on plant growth. • A new integrated framework is proposed to identify flash drought (FD) events. • FD with greater frequency, longer pentads, and stronger intensity since 1990s. • Vegetation structure and physiological function respond rapidly to FD. • The response time of plant activity to FD is different in diverse climate-water regions. [ABSTRACT FROM AUTHOR]

Resource sharing through rhizomes of clonal plants supplements locally available nutrients to enhance recruitment and growth in resource-limited environments. We investigated whether Arundo donax, an invasive clonal plant, can benefit from clonal integration. Sharing resources between ramets can facilitate resprouting from mowing, fire and herbicide treatments, but it is unknown whether clonal integration contributes to A. donax invasion success. Our first objective was to determine whether A. donax rhizomes transported water between ramets. Hydrogen isotopic-enriched water was applied on three 1 m diameter areas, and rhizome and soil samples were collected beyond the watering zone after 5, 24 and 48 h of the last watering. Logistic modelling indicated that water was able to move laterally at least 3.5 m. The second objective was to determine whether clonal integration enhanced growth and survival of A. donax ramets. We compared growth-related responses in paired 1 m2 plots with severed and intact rhizomes. In the first 19 days, rhizome severing nearly doubled ramet density, while by 77 days, the intact rhizomes produced 67% taller stems with 49% greater diameter and showed higher survival rate after flooding. This study provides initial evidence that physiological integration could be an important mechanism in A. donax, which can enhance its competitive abilities, accelerate rates of encroachment and strengthen its capability to recolonise disturbed areas. Our results highlight an important consideration of clonal invasive species in weed management. [ABSTRACT FROM AUTHOR]

Introduction. The Chinese jujube tree always presents some unfavorable performances because its vegetative growth is very vigorous. Our study was conducted to apply root pruning to test whether it can effectively inhibit the vigorous vegetative growth by regulating the competitive ability of the root system for water and nutrients. Materials and methods. For our experiment, roots were cut at three different distances from the trunk (light, moderate and severe root pruning) on both inter-row sides of jujube trees to the depth of 20 cm. Roots of control jujube trees were not pruned. Then we determined for three years the competitive indicators of Chinese jujube trees including the length, number and thickness of primary branches; photosynthetic characteristics and nutrient concentrations of leaves; hormone contents in the jujube head, flower number and fruiting percentage, yield, and fruit quality. Results and discussion. In the early stage after root treatment, root pruning decreased lots of indicators such as concentrations of nitrogen, phosphorus, and potassium in leaves, photosynthesis, transpiration, stomatal conductance, and intercellular CO2 concentration of leaves, relative to the same indicators as the control group. With the gradual emergence of new roots, these indexes appeared to have adverse patterns with respect to those in the early stage after root pruning. Compared with the control, root pruning significantly decreased the length and number of primary branches and flower number, but thickened primary branches, enhanced fruiting percentage and increased the amount of ethylene release of the jujube head in the whole experiment. Fruit quality was improved with root pruning, as indicated by increases in vitamin C and total sugar and a decrease in titrable acidity. No effects of root pruning were noticed on yield. From our results, we conclude that the removal of the root system at a distance of three times the trunk diameter (severe pruning) from the trunk is the most effective in regulating the competitive ability of the Chinese jujube tree. [ABSTRACT FROM AUTHOR]

Abiotic stresses such as extremes of temperature and pH, high salinity and drought, comprise some of the major factors causing extensive losses to crop production worldwide. Understanding how plants respond and adapt at cellular and molecular levels to continuous environmental changes is a pre-requisite for the generation of resistant or tolerant plants to abiotic stresses. In this review we aimed to present the recent advances on mechanisms of downstream plant responses to abiotic stresses and the use of stress-related genes in the development of genetically engineered crops. [ABSTRACT FROM AUTHOR]

The possible consequences of global warming on plant communities and ecosystems have wide-ranging ramifications. We examined how environmental change affects plant growth as a function of the variations in the microclimate along an urban-suburban climate gradient for two allergy-inducing, invasive plants, Humulus japonicus and Ambrosia artemisiifolia var. elatior. The environmental factors and plant growth responses were measured at two urban sites (Gangbuk and Seongbuk) and two suburban sites (Goyang and Incheon) around Seoul, South Korea. The mean temperatures and CO concentrations differed significantly between the urban (14.8 °C and 439 ppm CO) and suburban (13.0 °C and 427 ppm CO) sites. The soil moisture and nitrogen contents of the suburban sites were higher than those at the urban sites, especially for the Goyang site. The two invasive plants showed significantly higher biomasses and nitrogen contents at the two urban sites. We conducted experiments in a greenhouse to confirm the responses of the plants to increased temperatures, and we found consistently higher growth rates under conditions of higher temperatures. Because we controlled the other factors, the better performance of the two invasive plants appears to be primarily attributable to their responses to temperature. Our study demonstrates that even small temperature changes in the environment can confer significant competitive advantages to invasive species. As habitats become urbanized and warmer, these invasive plants should be able to displace native species, which will adversely affect people living in these areas. [ABSTRACT FROM AUTHOR]

Abstract: Derelict contaminated sites are often colonized spontaneously by plant species leading to a vegetal cover thought to limit particle dispersal and polluted water infiltration. Those plants must cope with soil pollutants through tolerance mechanisms that are not yet fully understood. Here, we focused our attention on a particular Asteraceae plant, Solidago canadensis, considered as invasive in Europe. S. canadensis spontaneously growing on either polluted (NM soil) or control soils dumped on experimental plots were studied for their physiological status, oxidative stress and 2D-DIGE of leaf extracts. S. canadensis tolerance to soil pollutants was demonstrated since growth rates, allocation to reproduction ratios and Fv/Fm ratios were similar in plants from control and NM soil. At the cell level, the catalase activity level was increased in plants collected on NM soil while lipoperoxidation was unaffected. Also, the leaf proteomic study revealed thirty down-regulated and sixty-six up-regulated proteins. Abundances of proteins related to oxidative stress, carbohydrate metabolism, ion transport were mainly up-regulated while those of proteins involved in cell cycle and transcription/translation were mostly down-regulated. Proteins associated to protein metabolism were either down- or up-regulated. Considered altogether, we highlighted that S. canadensis exhibited a complex proteome response when experiencing a multicontaminated soil. [Copyright &y& Elsevier]

Tobacco plants (Criollo 98) were sprayed with different concentrations (0, 0.1, 0.5, 1, 2.5 g.L-1) of chitosan polymer 30 days after planting (dap). 14 days after treatment, variations caused by chitosan on plant growth were measured, using the following variables: number of leaves, stem and roots length and dry mass. Polymer treatments caused stimulation and inhibition of the variables measured depending on the chitosan concentration tested. Changes in the protein and reducing carbohydrate contents were, also, obtain in tobacco leaves sprayed with chitosan, mainly increments above control at 37 dap, depending on the polymer concentration tested. Nitrato reductase activity was just induced above control at 37 dap with the highest concentration (2.5 g.L-1) tested. Also, defense markers evaluated were just induced, above control, at 33 dap, again depending on polymer concentration. β 1-3 glucanase activated at 1.0 g.L-1, while PAL activated with the three highest concentration (0.5-2.5 g.L-1) employed. According to results, there is no relation between the increasing of defense responses and changes on protein and reducing carbohydrates content; however, due to the complexity of the induced resistance response, it is necessary to look deeple in to this study by including other markers and different way of chitosan application. [ABSTRACT FROM AUTHOR]

Crenate broomrape (Orobanche crenata) is considered to be the major constraint for legume crops in Mediterranean countries. Strategies of control have been developed, but only marginal successes have been achieved. For the efficient control of the parasite, a better understanding of its interaction and associated resistance mechanisms at the molecular level is required. The pea response to this parasitic plant and the molecular basis of the resistance was studied using a proteomic approach based on 2D DIGE and MALDI-MSMS analysis. For this purpose, two genotypes showing different levels of resistance to O. crenata, as well as three time points (21, 25, and 30 d after inoculation) have been compared. Multivariate statistical analysis identified 43 differential protein spots under the experimental conditions (genotypes/treatments), 22 of which were identified using a combination of peptide mass fingerprinting (PMF) and MSMS fragmentation. Most of the proteins identified were metabolic and stress-related proteins and a high percentage of them (86%) matched with specific proteins of legume species. The behaviour pattern of the identified proteins suggests the existence of defence mechanisms operating during the early stages of infection that differed in both genotypes. Among these, several proteins were identified with protease activity which could play an important role in preventing the penetration and connection to the vascular system of the parasite. Our data are discussed and compared with those previously obtained in pea and Medicago truncatula. [ABSTRACT FROM PUBLISHER]

Abstract: Arbuscular mycorrhizal (AM) fungi convey well documented benefits to plant growth in domesticated species. We investigated AM in Solanum centrale, a desert shrub of central Australia and traditional food for Indigenous Australians. AM were observed in roots of S. centrale from wild and cultivated stands of different ages and management regimes. Greenhouse seedlings grown in sterilised sand were provided with no or minor additions of phosphorus, with or without AM fungi. Inoculated seedlings not fertilised with phosphorus exhibited moderate AM formation. Added phosphorus resulted in an absence of AM. Inoculation did not significantly affect dry weight, root length and plant height of seedlings fertilised with phosphorus but significantly increased the size of unfertilised seedlings. Inoculation significantly increased root phosphorus content, decreased root to shoot ratio and decreased root biomass at all phosphorus additions, despite the absence of observable AM. Thus it appears AM fungi in the root zone influenced certain plant characteristics, regardless of phosphorus nutrition. Overall, S. centrale benefited from the presence of AM through increased phosphorus uptake, but only when the seedlings were growing in soil with extremely low available phosphorus. The response was immediate in our experimental system and is likely to be important in the wild. [Copyright &y& Elsevier]

Plant compensatory growth is a phenomenon of exaggerated vegetative growth that occurs in plants as a result of mechanical damage (e.g., cutting or browsing). Because shoots, leaves, and other plant parts grow larger on plants undergoing compensation, they typically fall outside of the normal ranges given in plant identification keys and confuse students who are attempting to classify them. Here, we describe the conundrum faced by students collecting compensatory materials and offer suggestions on how to help students identify their 'plant-in-hand' and how to seize a teaching moment to examine and explain the underlying processes that lead to this fascinating plant response. [ABSTRACT FROM AUTHOR]

In order to maximize food intake per harvesting effort and minimize energy expenditures required to move between feeding patches in nature, herbivores such as moose (Alces alces L.) generally select large plant shoots when browsing in winter. To determine moose preferences for shoots of different morphologies, an experiment was conducted in northern British Columbia in which shoots from birches cut at different times of the growing season were fed in 2 consecutive years to eight human-habituated moose in cafeteria-style feeding trials. The results indicate that moose preferred smaller winter shoots of birches regardless of when the parent plant was cut and also appeared to reject larger shoots containing sylleptic branches. It is argued that the preferences for smaller shoots by moose detected in these trials should be observable under natural conditions, but are generally only supported by literature from some parts of Scandinavia. The findings underscore the importance that factors such as mouth filling per harvesting effort, snow depth and consistency, predators and browse patch distribution must have on foraging decisions made by moose while browsing in the wild. Implications of the findings include the significance of cutting time on the size of shoots produced by birch after cutting, how this affects moose browsing birch and, subsequently, how managers can theoretically use cutting time as a tool in forest cleaning operations to direct the foraging efforts of moose towards or away from forest plantations. [ABSTRACT FROM AUTHOR]

Nitrogen is a vital nutrient for sugarcane growth and development, which increases cane and sugar yields when it is rationally used. In this regard, an investigation was carried out for 27 years, with the objective of defining yield behavior with different doses of N applied to a sugarcane agroecosystem where burning is used to harvest. A long-term N level trial was conducted under unirrigated conditions, with four planting cycles and 24 harvests. An eutric typical Red Ferralitic soil was employed. Plant cane did not respond to N fertilization; the response was not systematic in the first ratoon, but it became more stable in the second one and there was always a response from the third ratoon on, whereas the required N doses were different per each cycle, it decreasing from the fourth ratoon on with regard to the previous cycles. In general, N needs diminished with rainfall increment. [ABSTRACT FROM AUTHOR]

The present study was carried out at Liliana Dimitrova Horticultural Research Institute, with the objective of evaluating the effect of nutrient solutions with different nitrogen/potassium fertigation ratios for protected tomato (HA-3019 hybrid) crop on biomass accumulation and macronutrient uptake within two planting times. Four N/K ratios (1:1.5; 1:2.0, 1:2.5 or production check, and 1:3.0) were studied in spring-summer season (March/July) and winter (September/January). Biomass accumulation (g.m-2) and N, P, K, Ca and Mg consumption were determined per plant organ and total biomass (g.m-2) for each treatment. In winter, dry weight and N, K and Ca uptake were significantly higher than in spring-summer season, whereas the top growing and nutrient consumption period corresponded to full production phase. The lowest leaf, stem and total biomass production corresponded to N/K ratio 1:1.5 in spring-summer; meanwhile dry fruit weight was significantly higher for N/K ratios 1:2.0 and 1:2.5. In winter season, significant fruit and total biomass values were recorded for N/K ratio 1:2.5 (production check); however, leave growth was similar in treatments 2, 3 and 4 (1:2.0, 1:2.5 and 1:3.0). Macronutrient extraction showed a similar behaviour to that obtained for biomass accumulation. [ABSTRACT FROM AUTHOR]

The review presents the current knowledge on the development and implementation of nanotechnology in crop production, giving particular attention to potential opportunities and challenges of the use of nano-sensors, nano-pesticides, and nano-fertilizers. Due to the size-dependent properties, e.g. high reactivity, targeted and controlled delivery of active ingredients, engineered nanomaterials (ENMs) are expected to be more efficient agrochemicals than conventional agents. Growing production and usage of ENMs result in the spread of ENMs in the environment. Because plants constitute an important component of the agri-ecosystem, they are subjected to the ENMs activity. A number of studies have confirmed the uptake and translocation of ENMs by plants as well as their positive/negative effects on plants. Here, these endpoints are briefly summarized to show the diversity of plant responses to ENMs. The review includes a detailed molecular analysis of ENMs-plant interactions. The transcriptomics, proteomics and metabolomics tools have been very recently employed to explore ENMs-induced effects in planta. The omics approach allows a comprehensive understanding of the specific machinery of ENMs occurring at the molecular level. The summary of data will be valuable in defining future studies on the ENMs-plant system, which is crucial for developing a suitable strategy for the ENMs usage. [Display omitted] • Review presents current achievements of nano-enabled chemicals for crop production. • Fate of pristine and transformed ENMs in plants is followed upon distinct conditions. • ENMs-induced effects on plant transcriptome, proteome, metabolome are discussed. • Future trends for ENMs-plant interactions are recommended for further omics studies. [ABSTRACT FROM AUTHOR]

Aphids are economically important insect pests of agriculture and forest crops. They feed on phloem sap by extremely efficient mouthparts modified into long and flexible stylets. Adaptation to phytophagy is completed by an extremely ductile reproduction system that can alternate biparental and parthenogenetic generations. In order to reach plant phloem, aphids must overcome plant defences, either physically and/or chemically. However, plants respond to aphid attack by activating defence genes that lead to the production of physical barriers and/or chemical toxic compounds (direct resistance). In addition, attacked plants can attract the natural enemies of aphids by releasing specific volatile compounds (indirect resistance). We can take advantage of these different types of resistance in order to enhance the sustainable control of these phytophagous insects. In this review we summarize the main aspects of plant-aphid interactions, focusing on those issues that can have an economic application. [ABSTRACT FROM AUTHOR]

Among the ecological alternatives reducing water stress effects, the arbuscular mycorrhizal fungal inoculation has been put into practice. Deepening into this subject, the work was aimed to test the stability of G. mosseae efficiency on tomato behaviour, growing out of its optimal period under water deficit conditions. Thus, two experiments were carried out under semi-controlled conditions, within half-late and late periods for tomato crop, inoculated and non-inoculated plants being subjected to water stress. Some variables related to mycorrhizal activity, plant growth and its water status were determined. The following indicators were evaluated: root colonization per arbuscular mycorrhizal fungi (% Col), visual density (DV), total dry weight as well as of leaves, stems and roots (g), foliar area (Sf) and water potential (ψ). Results proved strain efficiency per each indicator evaluated, which were higher in inoculated plants compared to non-inoculated ones, even though they were cultivated out of the optimal period. This experience suggests certain strain-crop specificity and particularly the best tomato development in symbiosis with G. mosseae under the studied conditions. [ABSTRACT FROM AUTHOR]

The present study was conducted under controlled conditions of temperature, humidity and light, with the aim of determining N+, K+ and total soluble sugar contents in rice (Oryza sativa L.) plants from LP-7 variety exposed to different NaCl levels. Plants developed in a hydroponic growth chamber. Evaluations were recorded at the beginning of the experiment, seven and 14 days after applying treatments and seven days after its recovery in a nutrient solution without NaCl. Evaluations consisted of determining Na+, K+ and total soluble sugar contents. The analysis of those variables showed differences concerning ion accumulation in all plant organs, and the tested variety behaved as a Na+ including one in its root system, which makes it sensitive to high NaCl concentrations. [ABSTRACT FROM AUTHOR]

Summary: Oomycetes from the genus Phytophthora are fungus-like plant pathogens that are devastating for agriculture and natural ecosystems. Due to their particular physiological characteristics, no efficient treatments against diseases caused by these microorganisms are presently available. To develop such treatments, it appears essential to dissect the molecular mechanisms that determine the interaction between Phytophthora species and host plants. Available data are scarce, and genomic approaches were mainly developed for the two species, Phytophthora infestans and Phytophthora sojae. However, these two species are exceptions from, rather than representative species for, the genus. P. infestans is a foliar pathogen, and P. sojae infects a narrow range of host plants, while the majority of Phytophthora species are quite unselective, root-infecting pathogens. To represent this majority, Phytophthora parasitica emerges as a model for the genus, and genomic resources for analyzing its interaction with plants are developing. The aim of this review is to assemble current knowledge on cytological and molecular processes that are underlying plant–pathogen interactions involving Phytophthora species and in particular P. parasitica, and to place them into the context of a hypothetical scheme of co-evolution between the pathogen and the host. [Copyright &y& Elsevier]

Regression estimates for determining browse shoot biomass from bite diameters and shoot basal diameters are commonly used to estimate biomass consumption and the impacts that herbivores have on range resources. Such estimates tend to be based on equations built from data taken across the continuum of shoot morphometries present on plants within a given study area. How these morphometric relationships differ between the shoots of undamaged and damaged (e.g., following browsing, shoot breakage, or brush-cutting) plants is unclear. To assess the effects of plant compensation and the importance of site on shoot morphometrics for Scouler's Willow (Salix scouleriana), we clipped and measured current annual shoots at 5 sites in central British Columbia. Each site had been previously brush-cut and current annual shoots were collected from both brush-cut and control willows. For each treatment and site, we developed separate regressions to predict shoot weight from length, weight from basal diameter, and length from basal diameter. Comparisons of individual regressions indicated that different regressions, or even different forms of regressions (i.e., power function versus linear), are needed to accurately predict shoot weight and length depending on whether or not plants are producing compensatory or non-compensatory shoots. For some willows in the same treatment category (brush-cut versus uncut), the appropriate regressions differed among some sites. These results suggest that the effects of plant compensation following mechanical damage have important implications to the extrapolation and interpretation of shoot morphometric relationships, and thus, biomass estimates across different study areas. [ABSTRACT FROM AUTHOR]

Abstract: We describe a system designed to experimentally elevate or depress water temperature in outdoor aquatic plant culture tanks while maintaining diurnal temperature fluctuations and other annual changes experienced by plants under field conditions. This system was developed to investigate the responses of potentially invasive aquatic plants to modified climatic conditions without the risk of experimental release. Water temperature is controlled by means of submerged electrical heating elements for warmed tanks, and by submerged refrigeration coils for cooled tanks. Vertical temperature gradients were removed by drawing water over the elements with a small pump and recirculating it to the top of the tank. Temperature records show that the system is capable of maintaining the set temperature differentials while replicating diurnal and seasonal temperature fluctuations. [Copyright &y& Elsevier]

Abstract: Glucosinolate accumulation and expression of glucosinolate biosynthetic genes were studied in response to four herbivores in Arabidopsis thaliana (L.) wild-type (Columbia) and mutant lines affected in defense signaling. Herbivory on wild-type plants led to increased aliphatic glucosinolate content for three of four herbivores tested, the aphid generalist Myzus persicae (Sulzer), the aphid specialist Brevicoryne brassicae (L.), and the lepidopteran generalist Spodoptera exigua Hübner. The lepidopteran specialist Pieris rapae L. did not alter aliphatic glucosinolate content in the wild-type, but indole glucosinolates increased slightly. Gene expression associated with aliphatic glucosinolate biosynthesis increased after feeding by all species, indicating that glucosinolate accumulation is not always regulated at the level of these gene transcripts. A. thaliana lines with mutations in jasmonate (coi1), salicylate (npr1), and ethylene signaling (etr1) diverged in gene expression, glucosinolate content, and insect performance compared to wild-type suggesting the involvement of all three modes of signaling in responses to herbivores. The coi1 mutant had much lower constitutive levels of aliphatic glucosinolates than wild-type but content increased in response to herbivory. In contrast, npr1 had higher constitutive levels of aliphatic glucosinolates and levels did not increase after feeding. Glucosinolate content of the etr1 mutant was comparable to wild-type and did not change with herbivory, except for P. rapae feeding which elicited elevated indolyl glucosinolate levels. Unlike the wild-type response, gene transcripts of aliphatic glucosinolate biosynthesis did not generally increase in the mutants. Both glucosinolate content and gene expression data indicate that salicylate and ethylene signaling repress some jasmonate-mediated responses to herbivory. [Copyright &y& Elsevier]

This work was carried out with the objective of determining the answer to plant growth and water relations of two rice varieties (Oryza sativa L.) when being exposed to different NaCl levels. Plants were developed in a growth chamber under hydroponic conditions. Evaluations were carried out at the beginning of the experiment, at seven and 14 days of having applied treatments and after seven days of recovery. Evaluations consisted of the biomass expressed as fresh and dry matter from roots and the air part, stomatal conductance, transpiration as well as leaf, osmotic, pressure and osmotic potentials at full turgor. The analysis of plant behavior indicated that they modified growth as much as water relations when exposed to saline conditions. It was also appreciated that under these conditions, plants developed the osmotic adjustment mechanism. [ABSTRACT FROM AUTHOR]

During two seasons (2003-2004 and 2004-2005), from the end of October to March, the effect of applying liquid humus (HL) was evaluated on the biological, productive yields and fruit quality of tomato Amalia variety. With this aim, two experiments were carried out, totally randomized under a small farmer's production conditions from Havana province, consisting of an Eutric compacted Red Ferralitic soil, where studies of some of its physico-chemical properties were made, that offered the information of being a soil with adequate properties for a good crop development. The biological indicators evaluated are stem length and diameter, number of leaves and inflorescences, productive indicators (number and fruit weight per plant), indicators of external fruit quality (polar and equatorial diameters) and internal quality (acidity, SST, ºBrix, vitamin C, dry weight), agricultural yield (t.ha-1) and the economic analysis per each treatment. For 2004-2005 season, the infestation index as well as the social impact were evaluated based on fruit quality. Results show the sensitivity of this tomato variety before the biostimulating action of liquid humus, applied to leaves in two doses at intervals of 15 days and concentrations of 1 mL HL/30 mL and 1 mL HL/40 mL water, seven days after transplanting (ddt), increasing the biological, productive yields, quality and social impact, with productive stage reduction, under a small farmer's production conditions, they being economically feasible, mainly HL at 1/30 concentration. [ABSTRACT FROM AUTHOR]

Many investigators consider that the dominance of a species on another in a natural ecosystem, is not only owed to competition, but also to the allelopathic effect among plants. Allelopathic effects damage partially or totally plant germination and growth; also they can be positive or negative, direct and indirect, according to the concentration of substances. Damages seem to depend on the influence of different factors like species and variety, residues and affected plants, quantity, place and climate influencing soil nutritional stages, their microbial activity and other characteristics. The presence of a dead covering on the soil, for many consecutive years, affects the development of certain agricultural crops; this is a fundamental element to a successful direct seeding, as a result of removing undesirable plants. The present work pretends to approach some topics on the phenomenon of allelopathy, to deepen on its agroecological and evolutionary meaning, its damages or benefits as well as its application and use in agriculture and its effects on weed crops. [ABSTRACT FROM AUTHOR]

Banana production in East Africa is threatened by declining yields partly caused by plant-parasitic nematodes. Attempts to ameliorate this damage are hampered by a lack of information on the characteristics of the root systems of healthy and nematode infested roots of commonly grown banana cultivars. An experiment in hydroponic culture, where healthy root systems were established, demonstrated that there were differences in number, size and distribution of primary, secondary and tertiary roots among the cultivars Nabusa, Pisang Awak and Sukali Ndizi. Field experiments carried out at three sites in Uganda showed that nematode damage on the same cultivars increased the number of primary roots and root bases, either increased or decreased root length depending on the cultivar or nematode species involved, but always decreased root length density. Root number and size are probably critical factors in determining plant tolerance to nematodes. Our findings should help plant breeding programmes, which must establish those selection criteria that are most likely to reduce the debilitating effects of nematode damage. [ABSTRACT FROM AUTHOR]

Abstract: Simulated herbivory has often been used as a substitute for actual herbivory when assessing the effects of herbivores on plants. However, mechanical damage does not always produce the same response as herbivore feeding. Similarity of plant response should be determined before mechanical damage is used as a surrogate for actual herbivory. This study compared two types of mechanical leaf tissue removal with actual herbivory on alligator weed [Alternanthera philoxeroides (Martius) Grisebach (Amaranthaceae)], a significant wetland weed in Australia. We contrasted the effects of simulated herbivory with those of actual herbivory by the alligator weed flea beetle, Agasicles hygrophila Selman and Vogt (Chrysomelidae: Alticinae), on plant growth and reproduction. There was no significant difference in the response of plant biomass to the three herbivory treatments. However, stem length and the number of stem nodes were reduced more by beetle damage than by the two simulated treatments. This was likely caused by preferential feeding on young leaf tissue and/or feeding damage to stem tissue as leaf tissue quality decreased at greater defoliation levels. To more closely mimic alligator weed response to A. hygrophila adult feeding for variables other than biomass, simulated damage methods should consider damage to new growth and stem tissue. [Copyright &y& Elsevier]

There is growing concern that air pollution may have adverse impacts on crops in developing countries, yet this has been little studied. This paper addresses this issue, for a major leguminous crop of the Indian sub continent, examining the effect of air pollution in and around an Indian city. A field study was conducted using a gradient approach to elucidate the impact of air pollutants on selected production characteristics of Vigna radiata L. cv. Malviya Jyoti (mung bean) plants grown from germination to maturity at locations with differing concentrations of air pollutants around peri-urban and rural areas of Varanasi. The 6 -h daily mean SO2, NO2 and O3 concentrations varied from 8.05 to 32.2 ppb, 11.7 to 80.1 ppb and 9.7 to 58.5 ppb, respectively, between the sites. Microclimatic conditions did not vary significantly between the sites. Changes in plant performance at different sites were evaluated with reference to ambient air quality status. Reductions in biomass accumulation and seed yields were highest at the site experiencing highest concentrations of all three gaseous pollutants. The magnitude of response indicated that at peri-urban sites SO2, NO2 and O3 were all contributing to these effects, whereas at rural sites NO2 and O3 combinations appeared to have more influence. The quality of seed was also found to be negatively influenced by the ambient levels of pollutants. It is concluded that the air pollution regime of Varanasi City causes a major threat to mung bean plants, both in terms of yield and crop quality, with serious implications for the nutrition of the urban poor. [ABSTRACT FROM AUTHOR]

Abstract: The influence of arsenic and Cucumber mosaic virus (CMV), applied separately and simultaneously on young tomato plants was studied. The plants were cultivated in containers under glasshouse conditions. Four main variants were arranged. The first one was without additional As pollution of soil, named as a control, and the other three variants, with As added at 25, 50 and 100mgkg−1 to dry soil respectively. Half of the plants in each experimental container were inoculated with CMV and the rest uninoculated. A clear response in plant behavior under the conditions of biotic and abiotic stress was estimated. Both arsenic and virus infection had a negative effect on tomato plants by limiting the growth of their roots and above growth parts. The changes in roots were more significant than of stems. Virus infection was a stronger stress factor than arsenic applied at levels of 25 and 50mgkg−1. The effect of each stress factor applied separately was enhanced in cases of their simultaneous application. The strongest negative effect was manifested in the infected plants, treated with excess arsenic of 100mgkg−1. It was established that the infection, caused by CMV in tomatoes, was affected by the presence of arsenic in the soil and concentration of the latter. Doses of 25 and 50mgkg−1 were favorable for infection development, while the dose of 100mgkg−1 was an inhibitor. Virus infection induced stronger specific peroxidase activity (SPOA) than As treatment. The combination of both stress factors reduced the positive peroxidase response caused by virus infection. Arsenic at rate 50 and 100mgkg−1, virus infection and the combination of both stress factors at 25mgkg−1 reduced chlorophyll a, chlorophyll b and carotenoid content The virus infection in cases of the higher arsenic doses reduced the As effect. There was an interaction between the two effects of biotic and abiotic stress. When arsenic and virus infection were applied simultaneously, they caused modification of the effect of each stress on the plants, when applied separately. [Copyright &y& Elsevier]

The response of plants to temperature has gained renewed interest as researchers speculate on the biotic response to climate change. It is of particular interest in the Arctic, due to recent warming trends and anticipated continued warming for the region. This long-term, multispecies study confirms that changes in temperature affect the functioning of plants in their natural environment. It also demonstrates that the influence of temperature should be considered in the context of natural variability within a given location. The study examined natural temperature gradients, interannual climate variation, and experimental warming at sites near Barrow (71°18' N, 156°40' W) and Atqasuk (70°29' N, 157°25' W) in northern Alaska, USA. At each of the four sites, 24 plots were experimentally warmed for 5-7 years with small, open-top chambers, and plant growth and phenology were monitored; an equal number of unmanipulated control plots were monitored. The response of seven traits from 32 plant species occurring in at least one site is reported when there were at least three years of recordings. Plants responded to temperature in 49% of the measured traits of a species in a site. The most common response to warming was earlier phenological development and increased growth and reproductive effort. However, the total response of a species, for all traits examined, was individualistic and varied among sites. In 14% of the documented responses, the plant trait was correlated with thawing degree-day totals from snowmelt (TDDsm), and temperature was considered the dominant factor. In 35% of the documented responses, the plant trait responded to warming, but the interannual variation in the trait was not correlated with TDDsm and temperature was considered subordinate to other factors. The abundance of temperature responses that were considered subordinate to other factors suggests that prediction of plant response to temperature that does not account for natural variability may overestimate the importance of temperature and lead to unrealistic projections of the rate of vegetation change due to climate warming. [ABSTRACT FROM AUTHOR]

The potential for metabolic fingerprinting via Fourier-transform infrared (FT-IR) spectroscopy to provide a novel approach for the detection of plant biochemical responses to N deposition is examined. An example of spectral analysis using shoot samples taken from an open top chamber (OTC) experiment simulating wet ammonium deposition is given. Sample preparation involved oven drying and homogenisation via mill grinding. Slurries of a consistent dilution were then prepared prior to FT-IR analysis. Spectra from control, 8 and 16 kg N ha-1 yr-1 treatments were then subjected to cross-validated discriminant function analysis. Ordination diagrams showed clear separation between the three N treatments examined. The potential for usingCalluna vulgaris(L.) Hull as a bioindicator of N deposition is further evident from these results. The results also clearly demonstrate the power of FT-IR in discriminating between subtle phenotypic alterations in overall plant biochemistry as affected by ammonium pollution. [ABSTRACT FROM AUTHOR]

Treatment of Jaborosa magellanica with artificial UV-B radiation caused changes in plant growth, plant chemistry and increase DNA polymorphisms. Spectrophotometric analysis showed that UV-B radiation decreases the chlorophylls content, and increases the amount of UV-B absorbing compounds (e.g., phenylpropanoids). Other UV-induced alterations include reduction in leaf area, alterations in plant architecture, and DNA damage. Using random primers and PCR amplification procedure, a high degree of polymorphism was detected when treated plants were compared to non-irradiated plants. These biochemical changes may be interpreted as plant response to UV-B radiation stress and as an indicator of DNA damage. [Copyright &y& Elsevier]