Changes in free amino acids and sugars in potatoes due to sulfate fertilization and the effect on acrylamide formation

To examine how sulfur deprivation may affect acrylamide formation in cooked potatoes, three varieties of potato were grown under conditions of either severe sulfur deprivation or an adequate supply of sulfur. In all three varieties sulfur deprivation led to a decrease in acrylamide formation, even though the levels of sugars, which are acrylamide precursors, were higher in tubers of the sulfur-deprived plants. In one variety the concentration of free asparagine, the other precursor for acrylamide, was also higher. There was a very close correlation between the concentration of asparagine in the tubers expressed as a proportion of the total free amino acid pool and the formation of acrylamide upon cooking, whereas sugars were poorly correlated with acrylamide. In potatoes, where concentrations of sugars are usually limiting, competition between asparagine and other amino acids participating in the Maillard reaction may be a key determinant of the amount of acrylamide that is formed during processing.

The role of seeds and airborne inoculum in the initiation of leaf blotch (Rhynchosporium secalis) epidemics in winter barley

Both airborne spores of Rhynchosporium secalis and seed infection have been implied as major sources of primary inoculum for barley leaf blotch (scald) epidemics in fields without previous history of barley cropping. However, little is known about their relative importance in the onset of disease. Results from both quantitative real-time PCR and visual assessments indicated that seed infection was the main source of inoculum in the field trial conducted in this study. Glasshouse studies established that the pathogen can be transmitted from infected seeds into roots, shoots and leaves without causing symptoms. Plants in the field trial remained symptomless for approximately four months before symptoms were observed in the crop. Covering the crop during part of the growing season was shown to prevent pathogen growth, despite the use of infected seed, indicating that changes in the physiological condition of the plant and/or environmental conditions may trigger disease development. However, once the disease appeared in the field it quickly became uniform throughout the cropping area. Only small amounts of R. secalis DNA were measured in 24 h spore-trap tape samples using PCR. Inoculum levels equivalent to spore concentrations between 30 and 60 spores per m3 of air were only detected on three occasions during the growing season. The temporal pattern and level of detection of R. secalis DNA in spore tape samples indicated that airborne inoculum was limited and most likely represented rain-splashed conidia rather than putative ascospores.

The influence of ultraviolet radiation on growth, photosynthesis and phenolic levels of green and red lettuce: potential for exploiting effects of ultraviolet radiation in a production system

Studies have shown that natural ultraviolet (UV) radiation increases secondary products such as phenolics but can significantly inhibit biomass accumulation in lettuce plants. In the work presented here, the effect of UV radiation on phenolic concentration and biomass accumulation was assessed in relation to photosynthetic performance in red and green lettuce types. Lettuce plants in polythene clad tunnels were exposed to either ambient (UV transparent film) or UV-free conditions (UV blocking film). The study tested whether growth reduction in lettuce plants exposed to natural UV radiation is because of inhibition of photosynthesis by direct damage to the photosynthetic apparatus or by internal shading by anthocyanins. Ambient levels of UV radiation did not limit the efficiency of photosynthesis suggesting that phenolic compounds may effectively protect the photosynthetic apparatus. Growth inhibition does, however, occur in red lettuce and could be explained by the high metabolic cost of phenolic compounds for UV protection. From a commercial perspective, UV transparent and UV blocking films offer opportunities because, in combination, they could increase plant quality as well as productivity. Growing plants continuously under a UV blocking film, and then 6 days before the final harvest transferring them to a UV transparent film, showed that high yields and high phytochemical content can be achieved complementarily.

Sub-irrigation of Petunia: benefits in dry summers

With the increasing frequency and magnitude of warmer days during the summer in the UK, bedding plants which were a traditional part of the urban green landscape are perceived as unsustainable and water-demanding. During recent summers when bans on irrigation have been imposed, use and sales of bedding plants have dropped dramatically having a negative financial impact on the nursery industry. Retaining bedding species as a feature in public and even private spaces in future may be conditional on them being managed in a manner that minimises their water use. Using Petunia x hybrida ‘Hurrah White’ we aimed to discover which irrigation approach was the most efficient for maintaining plants’ ornamental quality (flower numbers, size and longevity), shoot and root growth under water deficit and periods of complete water withdrawal. Plants were grown from plugs for 51 days in wooden rhizotrons (0.35 m (h) x 0.1 m (w) x 0.065 m (d)); the rhizotrons’ front comprised clear Perspex which enabled us to monitor root growth closely. Irrigation treatments were: 1. watering with the amount which constitutes 50% of container capacity by conventional surface drip-irrigation (‘50% TOP’); 2. 50% as sub-irrigation at 10 cm depth (‘50% SUB’); 3. ‘split’ irrigation: 25% as surface drip- and 25% as sub-irrigation at 15 cm depth (‘25/25 SPLIT’); 4. 25% as conventional surface drip-irrigation (‘25% TOP’). Plants were irrigated daily at 18:00 apart from days 34-36 (inclusive) when water was withdrawn for all the treatments. Plants in ‘50% SUB’ had the most flowers and their size was comparable to that of ‘50% TOP’. Differences between treatments in other ‘quality’ parameters (height, shoot number) were biologically small. There was less root growth at deeper soil surface levels for ‘50% TOP’ which indicated that irrigation methods like ‘50% SUB’ and ‘25/25 SPLIT’ and stronger water deficits encouraged deeper root growth. It is suggested that sub-irrigation at 10 cm depth with water amounts of 50% container capacity would result in the most root growth with the maximum flowering for Petunia. Leaf stomatal conductance appeared to be most sensitive to the changes in substrate moisture content in the deepest part of the soil profile, where most roots were situated.

Divergent evolutionary pattern of starch biosynthetic pathway genes in grasses and dicots

Starch is the most widespread and abundant storage carbohydrate in crops and its production is critical to both crop yield and quality. As regards the starch content in the seeds of crop plants, there are distinct difference between grasses (Poaceae) and dicots. However, few studies have described the evolutionary pattern of genes in the starch biosynthetic pathway in these two groups of plants. In this study, therefore, an attempt was made to compare the evolutionary rate, gene duplication and selective pattern of the key genes involved in this pathway between the two groups, using five grasses and five dicots as materials. The results showed (i) distinct differences in patterns of gene duplication and loss between grasses and dicots; duplication in grasses mainly occurred prior to the divergence of grasses, whereas duplication mostly occurred in individual species within the dicots; there is less gene loss in grasses than in dicots; (ii) a considerably higher evolutionary rate in grasses than in dicots in most gene families analyzed; (iii) evidence of a different selective pattern between grasses and dicots; positive selection may have occurred asymmetrically in grasses in some gene families, e.g. AGPase small subunit. Therefore, we deduced that gene duplication contributes to, and a higher evolutionary rate is associated with, the higher starch content in grasses. In addition, two novel aspects of the evolution of the starch biosynthetic pathway were observed.

The effectiveness of botanic garden collections in supporting plant conservation: a European case study

Europe has the greatest concentration of botanic gardens in the world, they cultivate extensive collections of plants that include samples of European threatened plant species. This study looks at the effectiveness of these collections in supporting species conservation. A three part study is presented: (1) the results of a survey and assessment of threatened plants in botanic gardens, as defined by the Bern Convention; (2) case studies illustrating current issues in the ex situ management of European threatened plant species; and (3) presentation of policy recommendations on further improving botanic garden contributions to European plant conservation. The survey indicated that of 119 European botanic gardens in 29 European countries, 105 are cultivating 308 of the 573 threatened plant species listed by the Bern Convention. The survey identified 25 botanic gardens in 14 countries undertaking 51 conservation projects focused on 27 Bern listed species. In particular this survey has established that the majority of taxa are held in a small number of collections, dominated by non-wild origin accessions, and are not adequately documented. The majority of specimens in botanic gardens are cultivated out of the range country and not contributing to a specific conservation project. We review the genetic representation and documentation of origin in collections. Existing plant collections contain representatives of populations, now lost in the wild and maintain samples of at least nine European plant taxa identified as 'Extinct in the Wild'. However, inadequate standards of record keeping has compromised the conservation value of many collections. We highlight the dangers of hybridisation and disease in ex situ collections. The results suggest that botanic garden collections are skewed towards horticulturally robust and ornamental species and do not fully reflect priorities as defined by the Bern Convention. Recognising the limitations of traditional botanic garden collections we propose that botanic gardens more effectively utilise their two core competencies, namely scientific horticulture and public display and interpretation. The unique horticultural skills resident in European botanic gardens could be more effectively utilised through the application of horticulture to the management of wild populations.

Influence of earthworm Eisenia fetida on removal efficiency of N and P in vertical flow constructed wetland.

This study investigates biomass, density, photosynthetic activity, and accumulation of nitrogen (N) and phosphorus (P) in three wetland plants (Canna indica, Typha augustifolia, and Phragmites austrail) in response to the introduction of the earthworm Eisenia fetida into a constructed wetland. The removal efficiency of N and P in constructed wetlands were also investigated. Results showed that the photosynthetic rate (P n), transpiration rate (T r), and stomatal conductance (S cond) of C. indica and P. austrail were (p < 0.05) significantly higher when earthworms were present. The addition of E. fetida increased the N uptake value by above-ground of C. indica, T. augustifolia, and P. australis by 185, 216, and 108 %, respectively; and its P uptake value increased by 300, 355, and 211 %, respectively. Earthworms could enhance photosynthetic activity, density, and biomass of wetland plants in constructed wetland, resulting in the higher N and P uptake. The addition of E. fetida into constructed wetland increased the removal efficiency of TN and TP by 10 and 7 %, respectively. The addition of earthworms into vertical flow constructed wetland increased the removal efficiency of TN and TP, which was related to higher photosynthetic activity and N and P uptake. The addition of earthworms into vertical flow constructed wetland and plant harvests could be the significantly sustainable N and P removal strategy

Comparison of pollinators and natural enemies: a meta-analysis of landscape and local effects on abundance and richness in crops

To manage agroecosystems for multiple ecosystem services, we need to know whether the management of one service has positive, negative, or no effects on other services. We do not yet have data on the interactions between pollination and pest-control services. However, we do have data on the distributions of pollinators and natural enemies in agroecosystems. Therefore, we compared these two groups of ecosystem service providers, to see if the management of farms and agricultural landscapes might have similar effects on the abundance and richness of both. In a meta-analysis, we compared 46 studies that sampled bees, predatory beetles, parasitic wasps, and spiders in fields, orchards, or vineyards of food crops. These studies used the proximity or proportion of non-crop or natural habitats in the landscapes surrounding these crops (a measure of landscape complexity), or the proximity or diversity of non-crop plants in the margins of these crops (a measure of local complexity), to explain the abundance or richness of these beneficial arthropods. Compositional complexity at both landscape and local scales had positive effects on both pollinators and natural enemies, but different effects on different taxa. Effects on bees and spiders were significantly positive, but effects on parasitoids and predatory beetles (mostly Carabidae and Staphylinidae) were inconclusive. Landscape complexity had significantly stronger effects on bees than it did on predatory beetles and significantly stronger effects in non-woody rather than in woody crops. Effects on richness were significantly stronger than effects on abundance, but possibly only for spiders. This abundance-richness difference might be caused by differences between generalists and specialists, or between arthropods that depend on non-crop habitats (ecotone species and dispersers) and those that do not (cultural species). We call this the ‘specialist-generalist’ or ‘cultural difference’ mechanism. If complexity has stronger effects on richness than abundance, it might have stronger effects on the stability than the magnitude of these arthropod-mediated ecosystem services. We conclude that some pollinators and natural enemies seem to have compatible responses to complexity, and it might be possible to manage agroecosystems for the benefit of both. However, too few studies have compared the two, and so we cannot yet conclude that there are no negative interactions between pollinators and natural enemies, and no trade-offs between pollination and pest-control services. Therefore, we suggest a framework for future research to bridge these gaps in our knowledge.

Squirmish at the Oasis: an evening of performance and rant hosted by Agency of Noise at the Kinsgate Workshsops Trust in affiliation with Camden Arts Centre

Squirmish at the Oasis takes its name from Luigi Russolo's fourth noise network 'Skirmish at the Oasis' performed in Milan in 1913. 100 years on the Agency of Noise contemplate changes in technology and the culture industry that provoke new questions around the deliberate use of noise within music and art. Through live acts of enquiry and experimentation five artists unravel paradoxes associated with the use of noise in art, music and the gallery space. The works challenge tensions, contradictions and possible oxymorons that emerge through the use and acceptance of noise within an artistic framework. Featuring: DAISY DIXON / GRAHAM DUNNING / POLLYFIBRE / DANE SUTHERLAND / MARNIE WATTS

Relationships between plant traits and climate in the Mediterranean region: an analysis based on pollen data

Question: What are the correlations between the degree of drought stress and temperature, and the adoption of specific adaptive strategies by plants in the Mediterranean region? Location: 602 sites across the Mediterranean region. Method: We considered 12 plant morphological and phenological traits, and measured their abundance at the sites as trait scores obtained from pollen percentages. We conducted stepwise regression analyses of trait scores as a function of plant available moisture (α) and winter temperature (MTCO). Results: Patterns in the abundance for the plant traits we considered are clearly determined by α, MTCO or a combination of both. In addition, trends in leaf size, texture, thickness, pubescence and aromatic leaves and other plant level traits such as thorniness and aphylly, vary according to the life form (tree, shrub, forb), the leaf type (broad, needle) and phenology (evergreen, summer-green). Conclusions: Despite conducting this study based on pollen data we have identified ecologically plausible trends in the abundance of traits along climatic gradients. Plant traits other than the usual life form, leaf type and leaf phenology carry strong climatic signals. Generally, combinations of plant traits are more climatically diagnostic than individual traits. The qualitative and quantitative relationships between plant traits and climate parameters established here will help to provide an improved basis for modelling the impact of climate changes on vegetation and form a starting point for a global analysis of pollen-climate relationships

The regulation of seasonal flowering in the Rosaceae

Molecular mechanisms regulating the flowering process have been extensively studied in model annual plants; in perennials, however, understanding of the molecular mechanisms controlling flowering has just started to emerge. Here we review the current state of flowering research in perennial plants of the rose family (Rosaceae), which is one of the most economically important families of horticultural plants. Strawberry (Fragaria spp.), raspberry (Rubus spp.), rose (Rosa spp.), and apple (Malus spp.) are used to illustrate how photoperiod and temperature control seasonal flowering in rosaceous crops. We highlight recent molecular studies which have revealed homologues of TERMINAL FLOWER1 (TFL1) to be major regulators of both the juvenile to adult, and the vegetative to reproductive transitions in various rosaceous species. Additionally, recent advances in understanding of the regulation of TFL1 are discussed.

Soil phosphorus supply affects nodulation and N:P ratio in 11 perennial legume seedlings

Developing new perennial pasture legumes for low-P soils is a priority for Australian Mediterranean agro-ecosystems, where soil P availability is naturally low. As legumes tend to require higher P inputs than non-legumes, the ability of these plants to fix N2 under varying soil P levels must be determined. Therefore, the objective of this study was to investigate the influence of soil P supply on plant N status and nodule formation in 11 perennial legumes, including some novel pasture species. We investigated the effect of applying soil P, ranging from 0 to 384 μg P/g dry soil, on plant N status and nodulation in a glasshouse. Without exogenous P supply, shoot N concentration and N : P ratio were higher than at 6 μg P/g soil. Shoot N concentration and N : P ratio then changed little with further increase in P supply. There was a close positive correlation between the number of nodules and shoot P concentration in 7 of the 11 species. Total nodule dry weight and the percentage of plant dry weight that consisted of nodules increased when P supply increased from 6 to 48 μg P/g. Without exogenous P addition, N : P ratios partitioned into a two-group distribution, with species having a N : P ratio of either >70 or <50 g/g. We suggest that plants with a high N : P ratio may take up N from the soil constitutively, while those with a low N : P ratio may regulate their N uptake in relation to internal P concentration. The flexibility of the novel pasture legumes in this study to adjust their leaf N concentrations under different levels of soil P supplements other published evidence of good growth and high P uptake and P-use efficiency under low soil P supply and suggests their potential as pasture plants in low-P soils in Australian Mediterranean agro-ecosystems warrants further attention.

Are ericoid mycorrhizas a factor in the success of Calluna vulgaris Heathland Restoration?

Methods used in the restoration of lowland heath vary depending on edaphic factors at a site and need for introduction of ericaceous propagules. This study investigates the effect of some methods on growth of an important ericaceous species, Heather (Calluna vulgaris). It also explores whether success of growth of C. vulgaris in restoration schemes is affected by its degree of colonization by ericoid mycorrhizal fungi (ERM). The success of Heather growth was compared at three sites, a control area of natural heathland and two restoration sites. These were a quarry where soil had been translocated but not chemically manipulated and a site on agricultural land where the top soil had been improved but then either stripped away or acidified prior to attempting heathland restoration. Propagules of C. vulgaris were applied either as turves or as clippings. Results show that clippings produced as dense a cover of C. vulgaris as turves over a period of 13 years and that plants in such swards can exhibit a degree of ERM colonization comparable to that found in mature plants growing in natural heathland. Young (<2 years of age) plants of C. vulgaris had less extensive mycorrhizal colonization of their roots, particularly when growing on restored agricultural soils. A relationship was found between lower levels of mycorrhizal colonization and smaller aboveground plant growth. Success of heathland restoration may be improved by finding means to enhance the rate and extent of mycorrhizal colonization of young C. vulgaris growing in a restoration environment.