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Yield Losses (yield + loss)
Selected AbstractsAssessment of potential approaches to improve Eucalyptus globulus kraft pulping yieldJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2007A. S. Santiago Abstract The main goal of this work is to study the potential approaches to improve polysaccharides retention during Eucalyptus globulus kraft pulping. The addition of anthraquinone to kraft pulping leads to the highest pulp yield while the addition of urea promotes lower depolymerization of polysaccharides (higher pulp viscosity), but does not have a significant effect on yield. The early interruption of kraft cooking followed by oxygen delignification is a reliable approach to increase pulp yield, particularly when pulping is interrupted at the end of the faster and more selective kinetic regime (bulk phase). Yield loss during oxygen delignification is considerably lower than that incurred in the last phase of kraft pulping. Pulping with OH,/HS, charge profiling, carried out with liquor injection in three different phases leads to a yield increase. However, this increase results from a lower total alkali charge applied when profiling pulping is compared to standard pulping conditions, rather than to alkali profiling. Standard kraft pulping with different active alkali (AA) charges demonstrated that this operational variable is determinant for pulp yield and viscosity. Pulping experiences with lower AA (14%) resulted in a higher and almost constant pulp viscosity and in a higher pulp yield, assigned to improved retention of both cellulose and xylan. During the last stage of pulping, cellulose content decreases, this being mainly responsible for the decrease of pulp yield, while xylan content is almost constant, a feature attributed to the peculiar structure of this E. globulus's hemicellulose. Copyright © 2007 Society of Chemical Industry [source] Field trial of serially passaged isolates of BYDV-PAV overcoming resistance derived from Thinopyrum intermedium in wheatPLANT BREEDING, Issue 3 2006F. Chain Abstract Barley yellow dwarf disease (BYDD) is one of the main viral diseases of small grain cereals. This disease, reported on numerous plant species of the Poaceae family, is caused by a complex of viral species including the species Barley yellow dwarf virus -PAV (BYDV-PAV, family Luteoviridae, genus Luteovirus), frequently found in western Europe. Resistance sources towards BYDD are scarce. Indeed, breeding-resistant genotypes is a long and expensive process. Thus, estimating the durability of the resistance genes before the achievement of selection would be an asset for breeders. One isolate of BYDV-PAV has been serially passaged on two hosts, ,Zhong ZH' and ,TC14', carrying a gene for partial resistance. The resulting viral population showed an increase of the speed of development of the infection in controlled conditions. In this study, these viral populations were evaluated in a 3-year field trial, including a susceptible host, ,Rendezvous', and a host carrying the resistance gene of ,TC14' in a ,Rendezvous' background, to assess the effect of serial passages in field conditions. Results indicate that isolates issued from serial passages on hosts carrying a gene for partial resistance induced increased damage in field conditions when compared with the initial isolate. Yield losses are mainly due to a decrease of the number of kernels per square metre. The interest on using partial resistance gene to control BYDD is discussed. [source] Effects of stem canker (Leptosphaeria maculans) and light leaf spot (Pyrenopeziza brassicae) on yield of winter oilseed rape (Brassica napus) in southern EnglandPLANT PATHOLOGY, Issue 4 2000Y. Zhou The relationships between yield loss and incidence or severity of stem canker and light leaf spot in winter oilseed rape were analysed by correlation and regression analyses, using data from experiments at Rothamsted, England in 1992/93, 1994/95 and 1995/96. Growth stages (GS) 6,3/6,4 and 4,0/4,5 were identified as the critical points for relating percentage yield loss to stem canker and light leaf spot (on stems), respectively. Critical point (CP) and area under disease progress curve (AUDPC) models relating percentage yield loss to combined incidence or severity of stem canker and light leaf spot (stems) in each experiment were constructed by linear regression. There were no differences in the CP models for incidence between 1992/93, 1994/95 and 1995/96 experiments, or in the AUDPC models for incidence between 1992/93 and 1994/95 experiments. Therefore, a general CP model relating percentage yield loss (,Y) to combined incidence of stem canker (Si) at GS 6,3/6,4 and light leaf spot (stems) (Li) at GS 4,0/4,5 was constructed using data from the three experiments: ,Y = 0·85 + 0·079Si + 0·065Li (R2 = 43·7%, P < 0·001, 92 df). A general AUDPC model relating ,Y to the AUDPC of combined incidence of stem canker (Sia) from GS 5·7 to GS 6·5 and light leaf spot (stems) (Lia) from GS 4·0 to GS 6·3 was constructed using data from the 1992/93 and 1994/95 experiments: ,Y = 0·07 + 0·00096Sia + 0·0026Lia (R2 = 43·6%, P < 0·001, 68 df). These two general yield-loss models were tested with data from Rothamsted in 1993/94 and Boxworth in 1992/93. The predictive accuracy of the CP model based on combined incidence of stem canker and light leaf spot (stems) was better than that of the AUDPC model. Yield losses predicted by summing the estimates from individual models for incidence of stem canker alone (GS 6,3/6,4) and light leaf spot alone (on leaves at GS 3,3) were greater than observed yield losses in experiments at Rothamsted in 1992/93, 1993/94, 1994/95 and 1995/96 and at Boxworth in 1992/93. [source] Using plant analysis to predict yield losses caused by sulphur deficiencyANNALS OF APPLIED BIOLOGY, Issue 1 2001MECHTELD M A BLAKE-KALFF Summary Yield losses in agricultural crops as a result of sulphur deficiency are increasing in the UK, because of the decrease in sulphur dioxide emissions and changes in fertiliser practices. Therefore, there is a need for a reliable and practical diagnostic indicator to predict early in the growing season whether it is necessary to apply S fertiliser, but also to avoid the application of fertiliser when not necessary. A successful diagnostic indicator should be reliable and stable throughout plant development, but also easily measured with great accuracy and as little effort as possible. In this paper the difficulties and problems with currently used diagnostic tests for S deficiency, such as total S, sulphate or the N:S ratio, will be discussed. A more reliable and practical indicator of S deficiency is the malate: sulphate peak area ratio which is at present being developed for use by commercial laboratories and their customers. [source] Effects of diseases on the growth and yield of spring linseed (Linum usitatissimum), 1988,1998ANNALS OF APPLIED BIOLOGY, Issue 3 2000S A M PERRYMAN Summary In spring linseed field experiments with fungicides at Rothamsted from 1988 to 1998, substantial yield losses assoeiated with diseases occurred in three years and slight losses could be associated with diseases in other years. These yield losses were related to decreases in yield components (thousand grain weights and number of capsules). Leaf browning was observed each year and percentage leaf area with browning was the disease factor most consistently related to yield losses (in five years). Yield loss relationships for these five years suggested that for each 10% increase in percentage leaf area with browning there was a yield loss of 0.10 to 0.18 t ha,1. Stem browning, lesions on capsules and powdery mildew were associated with yield losses in two years, three years and one year, respectively. Yield losses were greatest in years when the period of flowering and early capsule development in June and July was wetter than average; the predominant disease was grey mould (Botrytis cinerea) in wet years up to 1996, whereas pasmo (Mycosphaerella linicola) was most important in 1997 and 1998. Observed yield losses were small in hot, dry years when powdery mildew (Sphaerotheca lini) and verticillium (Verticillium dahliae) were the predominant diseases. [source] Impact of Water Stress on Maize Grown Off-Season in a Subtropical EnvironmentJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2007C. M. T. Soler Abstract During the last decade, the production of off-season maize has increased in several regions of Brazil. Growing maize during this season, with sowing from January through April, imposes several climatic risks that can impact crop yield. This is mainly caused by the high variability of precipitation and the probability of frost during the reproduction phases. High production risks are also partially due to the use of cultivars that are not adapted to the local environmental conditions. The goal of this study was to evaluate crop growth and development and associated yield, yield components and water use efficiency (WUE) for maize hybrids with different maturity ratings grown off-season in a subtropical environment under both rainfed and irrigated conditions. Three experiments were conducted in 2001 and 2002 in Piracicaba, state of São Paulo, Brazil with four hybrids of different maturity duration, AG9010 (very short season), DAS CO32 and Exceler (short season) and DKB 333B (normal season). Leaf area index (LAI), plant height and dry matter were measured approximately every 18 days. Under rainfed conditions, the soil water content in the deeper layers was reduced, suggesting that the extension of the roots into these layers was a response to soil water limitations. On average, WUE varied from 1.45 kg m,3 under rainfed conditions to 1.69 kg m,3 under irrigated conditions during 2001. The average yield varied from 4209 kg ha,1 for the hybrids grown under rainfed conditions to 5594 kg ha,1 under irrigated conditions during 2001. Yield reductions under rainfed conditions were affected by the genotype. For the hybrid DKB 333B with a normal maturity, yield was reduced by 25.6 % while the short maturity hybrid Exceler was the least impacted by soil water limitations with a yield reduction of only 8.4 %. To decrease the risk of yield loss, the application of supplemental irrigation should be considered by local farmers, provided that this practice is not restricted by either economic considerations or the availability of sufficient water resources. [source] Constructing life-tables for the invasive maize pest Diabrotica virgifera virgifera (Col.; Chrysomelidae) in EuropeJOURNAL OF APPLIED ENTOMOLOGY, Issue 4 2006S. Toepfer Abstract:, The western corn rootworm (Diabrotica virgifera virgifera LeConte, Col.; Chrysomelidae) is an alien invasive species in Europe. It is a univoltine species with eggs that overwinter in the soil and larvae that hatch in spring. Three larval instars feed on maize roots, which can cause plant lodging and yield loss of economic importance. Adults emerge between mid-June and early August and can reduce yields through intensive silk feeding. In order to provide a thorough understanding of the population dynamics of this invasive pest species in the invaded European region, complete age specific life-tables were constructed in two maize fields in southern Hungary assessing the significance of natural mortality factors acting on D. v. virgifera populations. This information provides a rational basis for devising sustainable integrated pest management programmes, in particular, by enabling the identification of vulnerable pest age intervals for the timely application of various management tools. The life-table for D. v. virgifera in Europe resulted in a total mortality of about 99% from the egg stage in the autumn to the emergence of adult females in the following year (KTotal = 2.48), which is comparable with North America. The highest reduction of D. v. virgifera numbers resulted from the mortality in first instar larvae (94% marginal death rate) and from the unrealized fecundity (80%). However, only the variation in mortality between years can change the generational mortality and thus influence population growth. High variation in the marginal death rate between fields and years was found in the second and third instar larval stages, and in the overwintering egg stage. These mortality factors therefore have the potential to cause changes in the total generational mortality. Furthermore, the life-table suggested that a high fecundity could compensate for a high generational mortality and would lead to population increase. [source] Biology and control of Dicladispa gestroi Chapuis (Col., Chrysomelidae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 9-10 2001V. Delucchi The beetle Dicladispa gestroi is known only from Madagascar, where it is considered to be a pest of rice. Research were carried out from 1885 to 1994 in the Alaotra lake region, the main rice-producing area of the country, characterized by a warm rainy season from October to April and a cool dry season from April to October. The adult beetles invade the rice nurseries and the first direct-seeded fields at the beginning of the rainy season; they have a gregarious behaviour and their feeding activity, together with the mines bored by the larvae, determines a change of colour from green to pale yellow in the damage areas, which resemble outbreak areas of rice leafhoppers. Oviposition takes place only on young rice plants in the tillering stage. Females emerging after the end of February enter a reproductive diapause and leave the rice fields to ,hibernate'. Temperature summations for the egg, larval, and pupal development, as well as for the preoviposition period have been calculated. There is no yield loss up to a larval density of 0.6 per leaf and this economic injury level is seldom exceeded in the Alaotra lake region. Life tables carried out under field conditions show that chalcid parasitoids are the main mortality factor and are responsible for the collapse of entire outbreak areas. Since the discovery of the rice yellow mottle virus in 1989 in the Alaotra lake region and the disease transmission by chrysomelids, the pest status of D. gestroi has changed and control measures have to be applied. However, to avoid interference with the action of the parasitoids, chemical applications should be limited to rice nurseries. [source] Study of the Biosynthesis of 1-Octen-3-ol Using a Crude Homogenate of Agaricus bisporus in a BioreactorJOURNAL OF FOOD SCIENCE, Issue 3 2008R.O. Morawicki ABSTRACT:, 1-Octen-3-ol and 10-oxo- trans -8-decenoic acid are metabolites of the breakdown of linoleic acid (LA) by mushroom enzymes. These compounds can be produced in a bioreactor using a crude mushroom homogenate and the exogenous addition of LA and oxygen. The factors' duration of blending, mushroom,buffer ratio, effect of a surfactant, whole against partially clarified reaction broths, purity of LA, and utilization of stumps instead of whole mushrooms were studied for their effect on reaction yield using a 1-L bioreactor. The results showed the feasibility of using the more inexpensive 60%-pure LA instead of the 99%-pure LA even when a yield loss was involved. Waste stumps could be used instead of whole mushrooms with a yield decline of 26%. [source] PCR-based Detection and Differentiation of Anthracnose Pathogens, Colletotrichum gloeosporioides and C. truncatum, from Vegetable Soybean in TaiwanJOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2006L. S. Chen Abstract Anthracnose of vegetable soybean sometimes occurs in summer and causes severe symptoms and yield loss in southern Taiwan. Despite previous reports that Glomerella glycines and Colletotrichum truncatum were causal agents of soybean anthracnose, C. truncatum and C. gloeosporioides (teleomorph G. cingulata), but not G. glycines, were identified as the major pathogens causing anthracnose on the pods and stems of vegetable soybeans from 2003 to 2005. Most strains of C. truncatum and C. gloeosporioides were derived from diseased pods. Morphological formation of fruiting bodies separates the Colletotrichum isolates into two groups. Colletotrichum truncatum forms acervuli only while C. gloeosporioides produces acervuli and/or perithecia. Based on the sequence variation in the ITS1 and ITS2 regions, C. truncatum isolates were highly similar (99,100% nucleotide identity) while C. gloeosporioides isolates diverged into two separate groups that were not associated with morphotype. For early detection of C. truncatum and C. gloeosporioides infection on vegetable soybean plants, two species-specific primer pairs Colg 1/Colg 2 (expected size of 443 bp) and Colg 1/CT 2 (375 bp) were designed that allowed differentiation of C. gloeosporioides and C. truncatum in multiplex polymerase chain reaction. [source] Costing yield loss from acidity, sodicity and dryland salinity to Australian agricultureLAND DEGRADATION AND DEVELOPMENT, Issue 5 2005S. Hajkowicz Abstract Salinity, sodicity and acidity are three major soil constraints that limit crop and pasture yields in Australia. In this paper estimates are made of the potential benefits arising from their treatment by measuring and mapping their impact on agricultural profit. This is achieved by estimating the increase in profit for Australia's main commodities that would occur if the three soil constraints were costlessly ameliorated. These estimates reveal the upper achievable limit on investment returns. They are also indicative of each soil constraint's economic significance to Australian agriculture. It was found that costless removal of salinity would increase annual profits by A$187 million, sodicity by A$1034·6 million and acidity by A$1584·5 million. This equates to 2·9,per,cent, 15·8,per,cent and 24·2,per,cent of total net economic return. It was also found that worsening salinity extent and severity over 2000,2020 has a present value of A$496,A$712 million. Although soil salinity is currently the focus of much public attention, this analysis suggests that from a production viewpoint the correction of sodic and acidic soils may create greater private economic benefit. Opportunities vary considerably among industries. In particular, there is considerable opportunity for the horticultural and viticultural sector to address acidity issues. Whether gross benefits translate into net benefits is a complex question requiring access to context and location-specific information. Copyright © 2005 John Wiley & Sons, Ltd. [source] Managing arable weeds for biodiversityPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 6 2007Jonathan Storkey Abstract As a result of the recent intensification of crop production, the abundance and diversity of UK arable weeds adapted to cultivated land have declined, with an associated reduction in farmland birds. A number of questions need to be addressed when considering how these declines can be reversed. Firstly, can the delivery of crop production and biodiversity be reconciled by spatially separating cropping from designated wildlife areas? A number of subsidised environmental schemes in the UK take this approach and are focused on establishing vegetation cover on uncropped land. However, because of the lack of regular disturbance in these habitats, they are dominated by perennials and they therefore have limited potential for promoting the recovery of annual weed populations. A number of farmland bird species also rely on the provision of resources in field centres, and it is therefore likely that the recovery of their populations will rely on weed management options targeted at the cropped areas of the field. This raises two further questions. Firstly, is it possible to identify beneficial weed species that are relatively poor competitors with the crop and also have biodiversity value? Secondly, are the tools available to manage these species at acceptable levels while controlling pernicious weeds? A number of approaches are being employed to answer these questions, including predicting yield loss from weed competition models and exploiting herbicide selectivity. The further development of these tools is crucial if farmer opposition to managing weeds in crops is to be overcome. Copyright © 2007 Society of Chemical Industry [source] Effects of prolonged restriction in water supply on photosynthesis, shoot development and storage root yield in sweet potatoPHYSIOLOGIA PLANTARUM, Issue 1 2008Philippus Daniel Riekert Van Heerden Besides the paucity of information on the effects of drought stress on photosynthesis and yield in sweet potato [Ipomoea batatas (L.) Lam.], available reports are also contradictory. The aim of this study was to shed light on the effects of long-term restricted water supply on shoot development, photosynthesis and storage root yield in field-grown sweet potato. Experiments were conducted under a rainout shelter where effects of restricted water supply were assessed in two varieties (Resisto and A15). Large decreases in stomatal conductance occurred in both varieties after 5 weeks of treatment. However, continued measurements revealed a large varietal difference in persistence of this response and effects on CO2 assimilation. Although restricted water supply decreased leaf relative water content similarly in both varieties, the negative effects on stomatal conductance disappeared with time in A15 (indicating high drought acclimation capacity) but not in Resisto, thus leading to inhibition of CO2 assimilation in Resisto. Chlorophyll a fluorescence measurements, and the relationship between stomatal conductance, intercellular CO2 concentration and CO2 assimilation rate, indicated that drought stress inhibited photosynthesis primarily through stomatal closure. Although yield loss was considerably larger in Resisto, it was also reduced by up to 60% in A15, even though photosynthesis, expressed on a leaf area basis, was not inhibited in this variety. In A15 yield loss appears to be closely associated with decreased aboveground biomass accumulation, whereas in Resisto, combined effects on biomass accumulation and photosynthesis per unit leaf area are indicated, suggesting that research aimed at improving drought tolerance in sweet potato should consider both these factors. [source] Association mapping of straighthead disorder induced by arsenic in Oryza sativaPLANT BREEDING, Issue 6 2009H. A. Agrama Abstract Straighthead is a physiological disorder in rice (Oryza sativa L.) resulting in sterile florets, poorly developed panicles and yield loss. Because of its sporadic nature and unidentified causes for the disorder, molecular marker assisted selection is essential for resistance improvement in breeding programmes. To take advantage of recent advances in gene-mapping technology, we executed a genome-wide association mapping to identify genetic regions associated with straighthead disorder using 547 accessions of germplasm from the USDA rice core collection. Straighthead was evaluated in arsenic treated soil and genotyping was conducted with 75 molecular markers covering the entire rice genome about every 25 cM. A mixed-linear model approach combining the principal component assignments with kinship estimates proved to be particularly promising for association mapping. The extent of linkage disequilibrium was described among the markers. Six markers were found to be significantly associated with straighthead, explaining 35% of the total phenotypic variation. However, only two SSR markers, RM413 and RM277 on chromosome 5 and 12, respectively, have a significant association with low rating indicating straighthead resistance. Confirmation of the marker-straighthead association using segregating populations is necessary before marker-assisted selection can be applied. [source] Pyramiding of genes conferring resistance to Tomato yellow leaf curl virus from different wild tomato speciesPLANT BREEDING, Issue 6 2008F. Vidavski Abstract Tomato (Solanum lycopersicum) production in tropical and subtropical regions of the world is limited by the endemic presence of Tomato yellow leaf curl virus (TYLCV). Breeding programmes aimed at producing TYLCV-resistant tomato cultivars have utilized resistance sources derived from wild tomato species. So far, all reported breeding programmes have introgressed TYLCV resistance from a single wild tomato source. Here, we tested the hypothesis that pyramiding resistances from different wild tomato species might improve the degree of resistance of the domesticated tomato to TYLCV. We have crossed TYLCV-resistant lines that originated from different wild tomato progenitors, Solanum chilense, Solanum peruvianum, Solanum pimpinellifolium, and Solanum habrochaites. The various parental resistant lines and the F1 hybrids were inoculated in the greenhouse using viruliferous whiteflies. Control, non-inoculated plants of the same lines and hybrids were exposed to non-viruliferous whiteflies. Following inoculation, the plants were scored for disease symptom severity, and transplanted to the field. Resistance was assayed by comparing yield of inoculated plants to those of the control non-inoculated plants of the same variety. Results showed that the F1 hybrids between the resistant lines and the susceptible line suffered major yield reduction because of infection, but all hybrids were more resistant than the susceptible parent. All F1 hybrids resulting from a cross between two resistant parents, showed a relatively high level of resistance, which in most cases was similar to that displayed by the more resistant parent. In some cases, the hybrids displayed better levels of resistance than both parents, but the differences were not statistically significant. The F1 hybrid between a line with resistance from S. habrochaites and a line with resistance from S. peruvianum (HAB and 72-PER), exhibited the lowest yield loss and the mildest level of symptoms. Although the resistance level of this F1 hybrid was not statistically different from the level of resistance displayed by the 72-PER parent itself, it was statistically better than the level of resistance displayed by the F1 hybrids between 72-PER and any other resistant or susceptible line. [source] Phylogenetic relationships and pathogenicity of Colletotrichum acutatum isolates from grape in subtropical AustraliaPLANT PATHOLOGY, Issue 3 2007M. A. Whitelaw-Weckert The identity of Colletotrichum acutatum as the causal pathogen of grape ripe-rot, which causes yield loss and a bitter taint that lowers wine quality in Australian subtropical wine-grape regions, was confirmed using species-specific primers. Cultural, morphological and molecular methods (RAPD-PCR and sequencing of parts of the 5·8S-ITS regions and the ,-tubulin-2 gene) were used to determine the phylogenetic relationships of Australian C. acutatum isolates from wine grapes and other horticultural crops. A combination of RAPD-PCR and ,-tubulin-2 gene data showed that all wine-grape ripe-rot isolates from northern regions of New South Wales (NSW) and Queensland belong to a proposed new C. acutatum group (A9), together with isolates from Australian strawberry, mango, blueberry and olive. The 5·8S-ITS sequences for these grape pathogens were identical to published sequences for an isolate from Cyclamen (the Netherlands) and differed by 1 bp from isolates from Capsicum (Taiwan) and orange (Costa Rica). The grape ripe-rot isolates from the Shoalhaven Valley (southern NSW) were clustered within two other C. acutatum groups: A2 and A5. In vitro infection studies showed that Australian C. acutatum isolates from almond, blueberry, chilli, grape, mango, olive, strawberry and tomato were able to infect grape and could also infect blueberry and strawberry, indicating a lack of host specificity. This lack of host specificity, the genetic similarity with non-grape isolates, and the fact that many of the non-grape hosts were isolated from wine-growing regions, suggest the potential for cross-infection between grape and other horticultural crops. [source] Effects of stem canker (Leptosphaeria maculans) and light leaf spot (Pyrenopeziza brassicae) on yield of winter oilseed rape (Brassica napus) in southern EnglandPLANT PATHOLOGY, Issue 4 2000Y. Zhou The relationships between yield loss and incidence or severity of stem canker and light leaf spot in winter oilseed rape were analysed by correlation and regression analyses, using data from experiments at Rothamsted, England in 1992/93, 1994/95 and 1995/96. Growth stages (GS) 6,3/6,4 and 4,0/4,5 were identified as the critical points for relating percentage yield loss to stem canker and light leaf spot (on stems), respectively. Critical point (CP) and area under disease progress curve (AUDPC) models relating percentage yield loss to combined incidence or severity of stem canker and light leaf spot (stems) in each experiment were constructed by linear regression. There were no differences in the CP models for incidence between 1992/93, 1994/95 and 1995/96 experiments, or in the AUDPC models for incidence between 1992/93 and 1994/95 experiments. Therefore, a general CP model relating percentage yield loss (,Y) to combined incidence of stem canker (Si) at GS 6,3/6,4 and light leaf spot (stems) (Li) at GS 4,0/4,5 was constructed using data from the three experiments: ,Y = 0·85 + 0·079Si + 0·065Li (R2 = 43·7%, P < 0·001, 92 df). A general AUDPC model relating ,Y to the AUDPC of combined incidence of stem canker (Sia) from GS 5·7 to GS 6·5 and light leaf spot (stems) (Lia) from GS 4·0 to GS 6·3 was constructed using data from the 1992/93 and 1994/95 experiments: ,Y = 0·07 + 0·00096Sia + 0·0026Lia (R2 = 43·6%, P < 0·001, 68 df). These two general yield-loss models were tested with data from Rothamsted in 1993/94 and Boxworth in 1992/93. The predictive accuracy of the CP model based on combined incidence of stem canker and light leaf spot (stems) was better than that of the AUDPC model. Yield losses predicted by summing the estimates from individual models for incidence of stem canker alone (GS 6,3/6,4) and light leaf spot alone (on leaves at GS 3,3) were greater than observed yield losses in experiments at Rothamsted in 1992/93, 1993/94, 1994/95 and 1995/96 and at Boxworth in 1992/93. [source] Inactivation of the CTD phosphatase-like gene OsCPL1 enhances the development of the abscission layer and seed shattering in riceTHE PLANT JOURNAL, Issue 1 2010Hyeonso Ji Summary Although susceptibility to seed shattering causes severe yield loss during cereal crop harvest, it is an adaptive trait for seed dispersal in wild plants. We previously identified a recessive shattering locus, sh-h, from the rice shattering mutant line Hsh that carries an enhanced abscission layer. Here, we further mapped sh-h to a 34-kb region on chromosome 7 by analyzing 240 F2 plants and five F3 lines from the cross between Hsh and Blue&Gundil. Hsh had a point mutation at the 3, splice site of the seventh intron within LOC_Os07g10690, causing a 15-bp deletion of its mRNA as a result of altered splicing. Two transferred DNA (T-DNA) insertion mutants and one point mutant exhibited the enhanced shattering phenotype, confirming that LOC_Os07g10690 is indeed the sh-h gene. RNA interference (RNAi) transgenic lines with suppressed expression of this gene exhibited greater shattering. This gene, which encodes a protein containing a conserved carboxy-terminal domain (CTD) phosphatase domain, was named Oryza sativa CTD phosphatase-like 1 (OsCPL1). Subcellular localization and biochemical analysis revealed that the OsCPL1 protein is a nuclear phosphatase, a common characteristic of metazoan CTD phosphatases involved in cell differentiation. These results demonstrate that OsCPL1 represses differentiation of the abscission layer during panicle development. [source] Crop traits and the tolerance of wheat and barley to foliar diseaseANNALS OF APPLIED BIOLOGY, Issue 2 2009I.J. Bingham Abstract The relationship between yield loss and disease severity can differ widely between crops. This has given rise to the concept of disease tolerance, with some crops exhibiting a smaller yield loss under a given severity of disease than others. Genetic improvement to minimise yield loss under disease is an attractive goal, as it exerts little or no selection pressure on pathogen populations, and could form a useful component of durable disease management programmes. However, progress towards this end requires a thorough understanding of the phenotypic traits that influence the response of yield to disease, their genetic control and the possible trade-offs involved with other desirable agronomic characteristics. This paper examines the candidate crop traits that may confer tolerance of foliar disease in wheat and barley and reviews evidence of genetic variation in their expression. In wheat grown under the relatively low light conditions of North-West Europe, post-anthesis source (assimilate supply) and grain sink capacity (capacity for dry matter accumulation) appear to be closely balanced. Traits associated with maintaining post-anthesis radiation interception and radiation use efficiency in spite of disease may confer tolerance. The most promising traits include a larger flag leaf and compensatory increases in photosynthetic rate in non-infected parts of leaves. In barley, yield is often more strongly sink limited, and early-season disease management is required to protect the formation of potential grain sites. A wider range of potential traits may influence tolerance including compensatory adjustments in leaf growth and morphology, and differences in the sensitivity of tiller and spikelet mortality to photoassimilate supply. Different methods for quantifying tolerance are suggested depending on the trait of interest. [source] Autumn sowing increases severity of pasmo (Mycosphaerella linicola) on linseed in the UKANNALS OF APPLIED BIOLOGY, Issue 1 2009S.A.M Perryman Abstract Surveys and field experiments showed pasmo to be the most serious disease affecting UK winter linseed in the 1997,98, 1998,99 and 1999,2000 growing seasons. Survey data indicated that pasmo was widespread in England and Scotland, causing extensive loss of leaves and stem and capsule symptoms, on both winter and spring linseed crops. In winter linseed experiments at ADAS Boxworth and Rothamsted, when severe epidemics occurred (1997,98 and 1999,2000), control of pasmo with one or two MBC fungicide sprays increased yield. In experiments when severe pasmo epidemics did not occur (1998,99), fungicide applications did not increase yield. In all three growing seasons, large numbers of air-borne Mycosphaerella linicola ascospores were collected in the summer months. At the time when the winter linseed crop was emerging and becoming established in October/November, there were more air-borne M. linicola ascospores in 1999 than in 1998. April/May rainfall was much greater in 1998 (135 mm) and 2000 (223 mm), when severe pasmo epidemics developed by July, than in 1999 (68 mm) when disease severity in July was less. Regression analyses suggested that yield decreased as percentage area affected by pasmo on leaves or stems in July increased. The formulae relating yield loss to pasmo severity, derived from these experiments, were combined with disease survey data to estimate, retrospectively, the UK national losses from pasmo. Estimated national losses from pasmo on winter linseed, although >50% of crops were sprayed with fungicide, were approximately £2.9M in 1998, £1.6M in 1999 and £0.37M in 2000 (when the area of winter linseed had decreased greatly). Estimated combined losses on winter and spring linseed were approximately £14.8M in 1998, £34.9M in 1999 and £11.0M in 2000. [source] A model of the effect of fungicides on disease-induced yield loss, for use in wheat disease management decision support systemsANNALS OF APPLIED BIOLOGY, Issue 1 2007A. Milne Abstract A model of the effect of foliar-applied fungicides on disease-induced yield loss is described, parameterised and tested. The effects of fungicides on epidemics of Septoria tritici (leaf blotch), Puccinia striiformis (yellow rust), Blumeria graminis f.sp. tritici (powdery mildew) and Puccinia triticina (brown rust) on winter wheat were simulated using dose,response curve parameters. Where two or more active substances were applied together, their joint action was estimated using an additive dose model where the active substances had the same mode of action or a multiplicative survival model where the modes of action differed. By coupling the model with models of wheat canopy growth and foliar disease published previously, it was possible to estimate disease-induced yield loss for a prescribed fungicide programme. The difference in green canopy area and, hence, interception of photosynthetically active radiation between simulated undiseased and diseased (but treated) crop canopies was used to estimate yield loss. The model was tested against data from field experiments across a range of sites, seasons and wheat cultivars and was shown to predict the observed disease-induced yield loss with sufficient accuracy to support fungicide treatment decisions. A simple method of accounting for uncertainty in the predictions of yield loss is described. Fungicide product, dose and spray timing combinations selected using the coupled models responded appropriately to disease pressure and cultivar disease resistance. [source] Effects of diseases on the growth and yield of spring linseed (Linum usitatissimum), 1988,1998ANNALS OF APPLIED BIOLOGY, Issue 3 2000S A M PERRYMAN Summary In spring linseed field experiments with fungicides at Rothamsted from 1988 to 1998, substantial yield losses assoeiated with diseases occurred in three years and slight losses could be associated with diseases in other years. These yield losses were related to decreases in yield components (thousand grain weights and number of capsules). Leaf browning was observed each year and percentage leaf area with browning was the disease factor most consistently related to yield losses (in five years). Yield loss relationships for these five years suggested that for each 10% increase in percentage leaf area with browning there was a yield loss of 0.10 to 0.18 t ha,1. Stem browning, lesions on capsules and powdery mildew were associated with yield losses in two years, three years and one year, respectively. Yield losses were greatest in years when the period of flowering and early capsule development in June and July was wetter than average; the predominant disease was grey mould (Botrytis cinerea) in wet years up to 1996, whereas pasmo (Mycosphaerella linicola) was most important in 1997 and 1998. Observed yield losses were small in hot, dry years when powdery mildew (Sphaerotheca lini) and verticillium (Verticillium dahliae) were the predominant diseases. [source] ORIGINAL ARTICLE: Propensity of marine reserves to reduce the evolutionary effects of fishing in a migratory speciesEVOLUTIONARY APPLICATIONS (ELECTRONIC), Issue 3 2009Erin S. Dunlop Abstract Evolutionary effects of fishing can have unwanted consequences diminishing a fishery's value and sustainability. Reserves, or no-take areas, have been proposed as a management tool for reducing fisheries-induced selection, but their effectiveness for migratory species has remained unexplored. Here we develop an eco-genetic model to predict the effects of marine reserves on fisheries-induced evolution under migration. To represent a stock that undergoes an annual migration between feeding and spawning grounds, we draw model parameters from Atlantic cod (Gadus morhua) in the northern part of its range. Our analysis leads to the following conclusions: (i) a reserve in a stock's feeding grounds, protecting immature and mature fish alike, reduces fisheries-induced evolution, even though protected and unprotected population components mix on the spawning grounds; (ii) in contrast, a reserve in a stock's spawning grounds, protecting only mature fish, has little mitigating effects on fisheries-induced evolution and can sometimes even exacerbate its magnitude; (iii) evolutionary changes that are already underway may be difficult to reverse with a reserve; (iv) directly after a reserve is created or enlarged, most reserve scenarios result in yield losses; and (v) timescale is very important: short-term yield losses immediately after a reserve's creation can give way to long-term gains. [source] Effects of elevated temperature and carbon dioxide on seed-set and yield of kidney bean (Phaseolus vulgaris L.)GLOBAL CHANGE BIOLOGY, Issue 8 2002P. V. Vara Prasad Abstract It is important to quantify and understand the consequences of elevated temperature and carbon dioxide (CO2) on reproductive processes and yield to develop suitable agronomic or genetic management for future climates. The objectives of this research work were (a) to quantify the effects of elevated temperature and CO2 on photosynthesis, pollen production, pollen viability, seed-set, seed number, seeds per pod, seed size, seed yield and dry matter production of kidney bean and (b) to determine if deleterious effects of high temperature on reproductive processes and yield could be compensated by enhanced photosynthesis at elevated CO2 levels. Red kidney bean cv. Montcalm was grown in controlled environments at day/night temperatures ranging from 28/18 to 40/30 °C under ambient (350 µmol mol,1) or elevated (700 µmol mol,1) CO2 levels. There were strong negative relations between temperature over a range of 28/18,40/30 °C and seed-set (slope, ,,6.5% °C,1) and seed number per pod (, 0.34 °C,1) under both ambient and elevated CO2 levels. Exposure to temperature >,28/18 °C also reduced photosynthesis (, 0.3 and ,,0.9 µmol m,2 s,1 °C,1), seed number (, 2.3 and ,,3.3 °C,1) and seed yield (, 1.1 and ,,1.5 g plant,1 °C,1), at both the CO2 levels (ambient and elevated, respectively). Reduced seed-set and seed number at high temperatures was primarily owing to decreased pollen production and pollen viability. Elevated CO2 did not affect seed size but temperature >,31/21 °C linearly reduced seed size by 0.07 g °C,1. Elevated CO2 increased photosynthesis and seed yield by approximately 50 and 24%, respectively. There was no beneficial interaction of CO2 and temperature, and CO2 enrichment did not offset the negative effects of high temperatures on reproductive processes and yield. In conclusion, even with beneficial effects of CO2 enrichment, yield losses owing to high temperature (> 34/24 °C) are likely to occur, particularly if high temperatures coincide with sensitive stages of reproductive development. [source] Water management tasks in the summer polders of the Nemunas lowland,IRRIGATION AND DRAINAGE, Issue 2 2006Antanas Lukianas plaine d'inondation; polders d'été; gestion des eaux Abstract Surplus water during floods as well as the low level of the soil surface determine the complicated ecological, economic and demographic conditions in the Nemunas delta. Subsequently, it leads to different types and intensity of use of farmland as well as different methods of water regime regulation: summer or winter type polders. The building of 17 summer polders in the 32,500,ha floodplain area was a compromise, seeking to improve farming conditions and maintain the stability of the flood regime and ecology in the delta. Field measurements and mathematical modelling were carried out. As study results have shown, grass yield losses due to flooding depend on the distribution of water levels and flood duration in the summer polders. Relative damage to agriculture is insignificant and makes up only 10,15% of the total amount of flood damage in the Nemunas lowland. The field measurements and hydraulic and mathematical modelling of flow and sediment regime as well as study of flooding and changed farming conditions also show that it is possible to reduce the height of floods and economic and ecological damage. Rearrangement of the system of protective dikes, regulation of the main river canal and water/sedimentation regime with the help of pumping stations, decrease of pollutant migration into the Curonian Lagoon and Baltic Sea, and recreation of natural meadows are important in that case. Copyright © 2006 John Wiley & Sons, Ltd. Des eaux excédentaires en période de crues et un faible niveau du sol déterminent les conditions écologiques, économiques et démographiques complexes du delta du fleuve Nemunas. En particulier, des types et intensités différentes dans l'utilisation des terres arables, ainsi que des méthodes différentes de régulation du régime des eaux: polders d'été ou d'hiver. La construction de 17 polders d'été sur 32 500,ha de plaine d'inondation a été une solution de compromis pour améliorer l'agriculture et maintenir la stabilité du régime des crues et de l'écologie du delta. Des mesures de terrain et des modèles mathématique ont été réalisés. D'après les résultats des études, les pertes de récolte d'herbe dûes aux crues dépendent de la distribution des niveaux d'eau et de la durée de la crue dans les polders d'été. L'impact négatif sur l'agriculture est négligeable et ne représente que 10 à 15% des dommages totaux dus aux crues dans le delta du fleuve Nemunas. Les mesures de terrain et la modélisation hydraulique et mathématique de l'écoulement et de la sédimentation, ainsi que l'analyse des crues et des modifications de production agricole, prouvent également qu'il est possible de réduire la hauteur des crues et de diminuer ainsi les dommages économiques et écologiques. Dans ce cas, il convient de réorganiser le système des digues de protection, de réguler le chenal principal du fleuve et le régime de sédimentation des eaux à l'aide de stations de pompage, de réduire les déversements polluants dans la lagune Curonian et la mer Baltique, et de régénérer des pâturages naturels. Copyright © 2006 John Wiley & Sons, Ltd. [source] Shade Effects on Phaseolus vulgaris L. Intercropped with Zea mays L. under Well-Watered ConditionsJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 3 2004M. Tsubo Abstract Field experiments were carried out under unstressed conditions of soil water during two summer crop growing seasons (1998,99 and 1999,2000 seasons) in a South African semi-arid region (Bloemfontein, Free State, South Africa). The aim of this study was to investigate shade effects on beans intercropped with maize in terms of plant mass and radiation use. The experimental treatments were two cropping systems (no shading/sole cropping and shading/intercropping) and two row orientations (north,south and east,west). At the top of bean canopies shaded by maize, incident radiation was reduced by up to 90 %. Shading reduced total dry matter of beans by 67 % at the end of the growing season, resulting in yield losses. The dry matter partitioning into leaf and stem (the ratios of leaf and stem to total biomass) was about 50 % higher in intercropping than sole cropping. In contrast, intercropped beans had 40 % lower dry matter partitioning into pod (the ratio of pod to total biomass). Fraction of radiation intercepted by sole-cropped beans steeply increased until canopy closure (0.9) and then slowly decreased, while fraction of radiation intercepted by intercropped beans remained constant between 0.0 and 0.2 throughout the growing seasons. However, intercropped beans had 77 % higher radiation use efficiency (RUE) than sole-cropped beans. In contrast, for maize, no effect of intercropping (shading) was found on growth, partitioning, yield, radiation interception or RUE. Consequently, lower bean yield losses can be attained in association with late shading rather than early shading. This can be controlled by growing crops with different temporal and spatial treatments. As regards row treatment, no effect of row direction was found on growth, partitioning, yield, radiation interception or RUE. [source] Forecasting migration of cereal aphids (Hemiptera: Aphididae) in autumn and springJOURNAL OF APPLIED ENTOMOLOGY, Issue 5 2009A. M. Klueken Abstract The migration of cereal aphids and the time of their arrival on winter cereal crops in autumn and spring are of particular importance for plant disease (e.g. barley yellow dwarf virus infection) and related yield losses. In order to identify days with migration potentials in autumn and spring, suction trap data from 29 and 45 case studies (locations and years), respectively, were set-off against meteorological parameters, focusing on the early immigration periods in autumn (22 September to 1 November) and spring (1 May to 9 June). The number of cereal aphids caught in a suction trap increased with increasing temperature, global radiation and duration of sunshine and decreased with increasing precipitation, relative humidity and wind speed. According to linear regression analyses, the temperature, global radiation and wind speed were most frequently and significantly associated with migration, suggesting that they have a major impact on flight activity. For subsequent model development, suction trap catches from different case studies were pooled and binarily classified as days with or without migration as defined by a certain number of migrating cereal aphids. Linear discriminant analyses of several predictor variables (assessed during light hours of a given day) were then performed based on the binary response variables. Three models were used to predict days with suction trap catches ,1, ,4 or ,10 migrating cereal aphids in autumn. Due to the predominance of Rhopalosiphum padi individuals (99.3% of total cereal aphid catch), no distinction between species (R. padi and Sitobion avenae) was made in autumn. As the suction trap catches were lower and species dominance changed in spring, three further models were developed for analysis of all cereal aphid species, R. padi only, and Metopolophium dirhodum and S. avenae combined in spring. The empirical, cross-classification and receiver operating characteristic analyses performed for model validation showed different levels of prediction accuracy. Additional datasets selected at random before model construction and parameterization showed that predictions by the six migration models were 33,81% correct. The models are useful for determining when to start field evaluations. Furthermore, they provide information on the size of the migrating aphid population and, thus, on the importance of immigration for early aphid population development in cereal crops in a given season. [source] Modelling the spatial configuration of refuges for a sustainable control of pests: a case study of Bt cottonJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2003C. Vacher Abstract The ,high-dose-refuge' (HDR) strategy is widely recommended by the biotechnology industry and regulatory authorities to delay pest adaptation to transgenic crops that produce Bacillus thuringiensis (Bt) toxins. This involves cultivating nontoxic plants (refuges) in close proximity to crops producing a high dose of Bt toxin. The principal cost associated with this strategy is due to yield losses suffered by farmers growing unprotected, refuge plants. Using a population genetic model of selection in a spatially heterogeneous environment, we show the existence of an optimal spatial configuration of refuges that could prevent the evolution of resistance whilst reducing the use of costly refuges. In particular, the sustainable control of pests is achievable with the use of more aggregated distributions of nontransgenic plants and transgenic plants producing lower doses of toxin. The HDR strategy is thus suboptimal within the context of sustainable agricultural development. [source] The Ozone Component of Global Change: Potential Effects on Agricultural and Horticultural Plant Yield, Product Quality and Interactions with Invasive SpeciesJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 4 2009Fitzgerald Booker The productivity, product quality and competitive ability of important agricultural and horticultural plants in many regions of the world may be adversely affected by current and anticipated concentrations of ground-level ozone (O3). Exposure to elevated O3 typically results in suppressed photosynthesis, accelerated senescence, decreased growth and lower yields. Various approaches used to evaluate O3 effects generally concur that current yield losses range from 5% to 15% among sensitive plants. There is, however, considerable genetic variability in plant responses to O3. To illustrate this, we show that ambient O3 concentrations in the eastern United States cause substantially different levels of damage to otherwise similar snap bean cultivars. Largely undesirable effects of O3 can also occur in seed and fruit chemistry as well as in forage nutritive value, with consequences for animal production. Ozone may alter herbicide efficacy and foster establishment of some invasive species. We conclude that current and projected levels of O3 in many regions worldwide are toxic to sensitive plants of agricultural and horticultural significance. Plant breeding that incorporates O3 sensitivity into selection strategies will be increasingly necessary to achieve sustainable production with changing atmospheric composition, while reductions in O3 precursor emissions will likely benefit world food production and reduce atmospheric concentrations of an important greenhouse gas. [source] Virus Resistance in Cereals: Sources of Resistance, Genetics and BreedingJOURNAL OF PHYTOPATHOLOGY, Issue 9 2009Frank Ordon Abstract In cereals, soil-borne viruses transmitted by the plasmodiophorid Polymyxa graminis (e.g., Barley mild mosaic virus, Barley yellow mosaic virus or Soil-borne cereal mosaic virus), have increased in importance due to the increase of the acreage infested and because yield losses cannot be prevented by chemical measures. Due to global warming, it is also expected that insect transmitted viruses vectored by aphids (e.g., Barley yellow dwarf virus, Cereal yellow dwarf virus), leafhoppers (Wheat dwarf virus) or mites (e.g., Wheat streak mosaic virus), will become much more important even in cooler regions. The environmentally most sound and also most cost effective approach to prevent high yield losses caused by these viruses is breeding for resistance. Therefore, in contrast to other reviews on cereal viruses, this study briefly reviews present knowledge on cereal-infecting viruses and emphasizes especially the sources of resistance or tolerance to these viruses and their use in molecular breeding schemes. [source] | |||||||||||||||||||