bluuebunny/crossref_metadata_2025_split huggingface dataset:
Allelopathic potential in rice (Oryza sativa L.) germplasm
Authors: Olofsdotter Maria , Navarez Domingo , Moody Keith 
Published: February 2008

SummaryAllelopathy is the direct influence of a chemical released from one living plant on the development and growth of another plant. The use of allelopathy to control weeds of food crops could contribute towards increasing yields in sustainable agricultural systems. Various research teams have identified several hundred rice accessions which show indications of allelopathic potential, 60 of them showing promising allelopathic activity against one or more weeds. These accessions have different origin and stage of improvement. This, combined with the involvement of several allelochemicals and the ability to release these chemicals, indicates that allelopathic potential is a polygenic characteristic weakly correlated with yield or other important agronomic features. Successful allelopathy research, however, must be focused both on the discovery and subsequent validation of allelopathic potential. Experimental factors such as choice of test plants, collection of allelochemicals, concentration, osmotic pressure and bioassay methodology need considerable attention together with validation through assays with known chemicals of known concentrations. Without validation using known chemicals, the contribution of allelopathic research remains obscure. Several putative allelochemicals are found in extracts of rice leaf and straw, decomposing straw, and in rice soil. Evidence that these chemicals are being released from living plants is still lacking, but as it is a prerequisite for allelopathic activity in nature, it must be proved. Methods of collecting test solutions from living plants need further description. Allelopathic activity is believed to be a joint action of several secondary metabolites, and this must be confirmed for rice. Dilution assays with mixtures of putative rice allelochemicals need to be conducted to evaluate possible synergistic effects. In validation, these mixture‐dose response curves must be compared with assays using collected test solutions. A joint, coordinated and focused research effort on rice allelopathy is necessary before the full potential of allelopathic cultivars can be realised.
Comparison of resistance to potyviruses within Solanaceae: infection of potatoes with tobacco etch potyvirus and peppers with potato A and Y potyviruses
Authors: VALKONEN J P T , KYLE M M , SLACK S A 
Published: February 2008

Summary.The reaction of several cultivated potato varieties (Solarium tuberosum L.) to three strains of tobacco etch potyvirus (TEV‐F, TEV‐Mex21 and TEV‐ATCC) and the reaction of several pepper lines (Capsicum annuum L. and C. chinense L.) to two strains of potato Y potyvirus (PVYO and PVYN) and one strain of potato A potyvirus (PVA‐M) was tested. The potato varieties included in this study carried resistance genes against PVY, PVA and potato V potyvirus, but all were susceptible to TEV and developed mottle and mosaic symptoms. TEV was readily transmitted by mechanical inoculation from tobacco and potato to potato, whereas transmission from pepper to potato occurred infrequently. TEV was transmitted through potato tubers, and from pepper to potato plants by aphids. Lack of detectable systemic infection following graft‐inoculation indicated extreme resistance to PVYO and PVA in several pepper lines. No pepper line was systemically infected with PVYN following mechanical inoculation (graft‐inoculation was not carried out with PVYN). The development of necrotic lesions following mechanical and graft‐inoculation indicated hypersensitive response to PVYO in several pepper lines which resembled the resistance responses to these potyvirus strains in potato. Results of this study together with previous work indicate that C. annuum cv. Avelar is resistant to four potyviruses [PVY, PVA, pepper mottle potyvirus (PepMoV) and some isolates of TEV]; C. annuum cv. Criollo de Morelos and C. chinense PI 152225 and PI 159236 are resistant to three potyviruses (PVY, PepMoV and PVA; and PVY, PepMoV and TEV, respectively); C. annuum 9093–1 and 92016–1 are resistant to PVY and PepMoV; and C. annuum cv. Jupiter and C. annuum cv. RNaky are resistant to PVYN and PVA.
Significance of secondary infections with lily symptomless carlavirus to cut‐flower production of Lilium
Authors: BLAKE M R , WILSON C R 
Published: February 2008

Summary.The commercial significance of secondary infections of lily symptomless carlavirus (LSV) to commercial Lilium cut‐flower producers was assessed by comparing growth of plants and quality of blooms produced from bulbs of eight Asiatic and two Oriental hybrid cultivars both infected and free from infection with LSV. In comparison to LSV‐free plants, LSV‐infected plants grown under Tasmanian commercial cut‐flower production conditions had decreased stem length (mean of 8.5% and 10.4% decrease across cultivars in each of two experiments; P= 0.007 and < 0.001) and fresh weight (18.8% and 23.4%; P= 0.008 and 0.004). Bud size was significantly decreased in one experiment (12.3%; P= 0.001), while bud number and vase life were not affected (P= 0.05). LSV‐infected plants grown in a temperature controlled glasshouse had decreased stem length (15.8%; P < 0.001) and petal length (8.7%; P= 0.001) but petal width and bud number were no different to LSV‐free plants (P= 0.05). The characters considered to be of greatest economic importance to cut flower producers (viz the number of inflorescences per stem, flower quality and vase life) were not or were only mildly affected by LSV‐infection in any cultivar and unlikely to be of major commercial concern.
A damaging outbreak of arabis mosaic nepovirus in blackcurrant, the occurrence of other nepoviruses in Ribes species, and the demonstration that alfalfa mosaic virus is the cause of interveinal white mosaic in blackcurrant
Authors: JONES A T , McGAVIN W J 
Published: February 2008

Summary.In a crop of blackcurrant (Ribes nigrum), cv. Baldwin in Eire, chlorotic mottling and ringspot symptoms in leaves on plants and severe crop loss was associated with infection with arabis mosaic nepovirus (ArMV) and the presence in the soil of its nematode vector, Xiphinema diversicaudatum. This is only the second report of ArMV damaging a crop of blackcurrant. Tomato black ring (TBRV) and raspberry ringspot nepoviruses were detected in single plants of redcurrant (R. rubrum) in England and flowering currant (R. sanguineum) in Scotland respectively; each of these infected plants showed foliar chlorotic line‐pattern symptoms. This is the first record of TBRV in redcurrant. A single blackcurrant plant in New Zealand showing symptoms typical of those described for interveinal white mosaic disease, contained alfalfa mosaic virus (AMV). When AMV particles were purified and concentrated from herbaceous test plants and mechanically inoculated to young blackcurrant plants, several became infected with AMV and most infected plants developed systemic symptoms typical of the original disease. This provides the strongest evidence to date that AMV is the causal agent of interveinal white mosaic disease.
Effect of the seed coat on water uptake and electrolyt leakage of sorghum (Sorghum bicolor (L.) Moench) seeds
Authors: SHEPHARD HELEN L , NAYLOR ROBERT E L 
Published: February 2008

Summary.Four seed lots of sorghum cultivar IS 34213 were obtained which had been harvested early or at full maturity and then dried either swiftly in the sun or slowly in the shade. The earlier harvested seeds were lighter, smaller and of lower density. Earlier harvested seeds had pericarps which permitted faster water uptake and greater leakage of electrolytes. Water uptake and electrolyte leakage were positively correlated. The method of seed drying had no effect on water uptake or leakage. Greater leakage was associated with lower final germination. The results are interpreted in relation to germination testing.
Water deficit, root demography, and the causes of internal blackening in field‐grown tomatoes:(Lycopersicon esculentum Mill.)
Authors: REID J B , WINFIELD DIANA , SORENSEN ISABELLE , KALE A J 
Published: February 2008

Summary.An internal blackening disorder may cause substantial losses in the value of tomatoes grown for processing. The disorder resembles an internal form of blossom‐end rot and appears to be more common in dry seasons. In an experiment to test whether the internal blackening is caused by water deficit and whether it is indeed blossom‐end rot, plots of cv. Cannery Row were irrigated to keep the soil moisture deficit <50 mm and others were sheltered from rain and not irrigated from early flowering onwards. Shoot growth (total and fruit dry mass) was measured destructively at intervals, and root growth and death nondestructively using minirhizotrons. There was a greater incidence of internal blackening and blossom‐end rot, and lower Ca concentrations, in the fruit of non‐irrigated plants. Root growth and root death were accelerated in these plants around the time that internally‐blackened fruit were set. Although the internal blackening syndrome shared some features with blossom‐end rot some differences were apparent in this experiment. It is suggested that internal blackening could have resulted from increased root competition for photosynthate, leading to abnormal seed development. Root turnover was appreciable (30–40% of the roots survived 28 days). This suggests there may be substantial errors in contemporary models of dry matter partitioning in tomato crops.
The land planarianAustraloplana sanguineavar.albaat a horticultural site in New Zealand
Authors: MATHER JANICE G , CHRISTENSEN OLE M 
Published: February 2008

Summary.Morphometric data and general observations of habitat conditions, feeding behaviour and reproductive biology are presented for the land planarianAustraloplana sanguineavar.alba, based upon a population established at a garden centre in Alexandra, South Island, New Zealand.The flatworm species considered in this study appears to be identical to an alien flatworm initially referred to asGeoplana sanguinea(Moseley) var.alba(Dendy) which has successfully colonised areas of the British Isles over the past few decades.The study also highlights the importance of garden centres and nurseries as modified habitats that provide favourable conditions for terrestrial planarians, implying that exotic flatworm species have the potential to spread and exist in pockets world‐wide.
Effect of increased CO2 concentration and temperature on the phyllosphere mycoflora of winter wheat flag leaves during ripening
Authors: MAGAN NARESH , BAXTER ESTHER S 
Published: February 2008

Summary.The impact of elevated carbon dioxide (CO2, 600/700 μmol mol‐1) and temperature (+ 4°C) on phyllosphere fungi colonising flag leaves of mini crops of winter wheat cv. Mercia between anthesis and harvest was determined in a computer‐controlled environment facility in 1993 and 1994. In both years the total fungal populations (cm2 leaf) were found to have increased due to exposure to either elevated CO2 and elevated CO2+ temperature treatments. This was mainly due to significant increases in populations of Cladosporium spp. (C. cladosporioides and C. herbarum) on the flag leaves during ripening. Other phyllosphere component species such as white and pink yeasts were not markedly affected by treatments. The range of fungal species found in such controlled environment chambers was narrower than that commonly found on flag leaves of field grown crops. Common and important colonisers of leaves and ripening ears such as Aureobasidium pullulans, Epicoccum nigrum and Fusarium spp. were seldom isolated.
Resistance of Hibiscus esculentus L. and Vigna sinensis (L.) Endl. to Pseudocercospora and plant peroxidase activity in relation to infection
Authors: LEINA M J , TAN T K , WONG S M 
Published: February 2008

Summary.Five cultivars of Hibiscus esculentus L. and six cultivars of Vigna sinensis (L.) Endl. were tested for their relative resistance to Pseudocercospora spp. Differences in susceptibility to the leaf spot pathogen were observed in both host and non‐host interactions. The H. esculentus cv. South Sea and V. sinensis cv. Purple Mart were most susceptible to Pseudocercospora abelmoschi and P. cruenta, respectively. The H. esculentus cv. Pure Luck was most tolerant to P. abelmoschi while the V. sinensis cv. KY Bush was highly resistant to P. cruenta. A distinct host‐specific interaction was observed among the different species of Pseudocercospora. Cultivar specific interactions were most pronounced between V. sinensis and P. cruenta. A direct correlation was observed between the variation in peroxidase activity in the soluble fraction of inoculated leaves and resistance to infection in H. esculentus and V. sinensis cultivars. The soluble fraction of inoculated leaves had higher peroxidase activity than either mitochondrial or chloroplast extracts.
Effect of ascochyta blight (Mycosphaerella pinodes) on yield components of single pea (Pisum sativum) plants under field conditions
Authors: TIVOLI B. , BEASSE C. , LEMARCHAND E. , MASSON E. 
Published: February 2008

Summary.Field studies were made in 1992 and 1993 to examine the yield components of pea inoculated with Mycosphaerella pinodes and those of healthy pea (sprayed with a mixture of flutriafol + chlorothalonil), in a split‐plot design with the cv. Solara sown at different plant densities. Ascochyta blight was severe on leaves and on internodes of the basal part of the plants; pods had few lesions. The number and length of stems per plant were the same for diseased and healthy plants. The number of reproductive nodes and pods per stem were affected by disease only in 1993. In 1992 and 1993 respectively, disease caused reductions in the number of seeds per stem of 18% and 25%, and in seed size of 13.5% and 16.7%, compared with healthy plants. The harvest index and total biomass were lower in diseased than in healthy plants and seed yield was reduced by 40% in diseased plots. These results show a high relationship between the disease parameters (disease mean on stipules/nodes 8–18/ and on internodes/nodes 5–15/, percentages of stipules or internodes with a disease score 4, and percentage of stems encircled by lesions), plant density and yield reduction.
The effect of reduced phytoalexin production on the resistance of upland cotton (Gossypium hirsutum) to verticillium and fusarium wilts
Authors: ELDON S. , HILLOCKS R J 
Published: February 2008

Summary.The effect on disease development of inhibiting the production of the sesquiterpenoid phytoalexin hemigossypol (HG) in cotton resistant to both verticillium and fusarium wilts was investigated. Inhibition was achieved by treating the plants with the sodium salt of compactin, a competitive inhibitor of hydroxy‐methylglutaryl (HMG) CoA reductase. Compactin treatment (150 μg litre‐1) reduced HG production by a mean of 48%. The enzyme inhibitor did not mimic symptoms in uninfected plants or significantly reduce the ability of the conidia of either Fusarium oxysporum f.sp. vasinfectum or Verticillium dahliae to germinate. Treatment of infected plants with compactin resulted in a breakdown of resistance to verticillium wilt but not to fusarium wilt. These results support the view that HG production is the primary mechanism of resistance to verticillium wilt, but not to fusarium wilt.
Peanut yellow spot virus: A distinct tospovirus species based on serology and nucleic acid hybridisation
Authors: SATYANARAYANA T. , REDDY K LAKSHMINARAYANA , RATNA A S , DEOM C M , GOWDA S. , REDDY D V R 
Published: February 2008

Summary.Nucleocapsids of peanut yellow spot virus (PYSV), purified from peanut (= groundnut) plant tissue, contained a protein with a molecular mass of 29 kDa. In ELISA and immuno‐blot analysis the virus did not react with tomato spotted wilt virus (TSWV), Impatiens necrotic spot virus (INSV) and peanut bud necrosis virus (PBNV) antisera. PYSV contained three RNA species, a large (L) RNA (c.8900 nucleotides), a medium (M) RNA (c.4800 nucleotides) and a small (S) RNA (c.3000 nucleotides), similar to other tospoviruses. In addition, a fourth RNA species of approximately 1800 nucleotides was also present in purified preparations. Hybridisation analysis under high stringency conditions revealed no hybridisation between PYSV RNAs and cDNA probes representing the nucleocapsid (N) gene, the glycoprotein (GP) gene and the 3' half of the RNA polymerase gene of PBNV. PYSV genomic RNAs also failed to hybridise with cDNA probes from the GP genes of TSWV and INSV. In reciprocal tests, the cDNA clones of PYSV S and M RNAs did not hybridise with any of the PBNV RNAs. Based on the absence of serological relationships between PYSV and PBNV, TSWV and INSV and lack of nucleotide homology based on hybridisation studies between the PYSV RNAs and cDNA clones from PBNV, TSWV and INSV, PYSV should be considered as a distinct species of the genus Tospovirus under a new serogroup, putatively designated ‘V’.
Enhanced cold tolerance of the entomopathogenic nematode Steinernema feltiae through genetic selection
Authors: GREWAL PARWINDER S , GAUGLER RANDY , WANG YI 
Published: February 2008

Summary.Cold sensitivity of entomopathogenic nematodes severely restricts their biological control potential in some environments. We selected the SN strain of Steinernema feltiae together with its bacterial symbiont, Xenorhabdus bovenii, for improved cold tolerance by repeated passage through the wax moth Galleria mellonella larvae at 15°C. Nematode virulence (total insect mortality and speed of kill) and establishment (initiation of nematode development following penetration) were evaluated after six (= 12–24 generations) and 12 passages (= 24–36 generations). Cold selection enhanced nematode virulence at the cooler temperatures. Virulence measured as total insect‐mortality at 8°C improved by 5.3‐ and 6.6‐fold after six and 12 passages, respectively. Only small improvements (1.2–1.5‐fold) were observed in speed of kill. Nematode establishment improved at all temperatures after 12 passages; the highest increase of 9‐fold was observed at 8°C. Our results lend support to the hypotheses that functional traits along a continuously distributed environmental variable are genetically correlated and that the area under the fitness function is not always constant. Trade‐offs in percentage mortality and speed of kill by the selected nematodes were observed at the warmer extreme after six passages of selection only. The implications of rapid changes in thermal sensitivity for economic mass‐production of nematodes are discussed.
Identification of Heterodera cysts by SOD isozyme electrophoresis profiles
Authors: MOLINARI S. , EVANS K. , ROWE J. , RUSSELL M. 
Published: February 2008

Summary.Superoxide dismutase (SOD), the enzyme which converts superoxide anions into hydrogen peroxide, has been found to be highly expressed in the cyst stage of a number of Heterodera species likely to occur together in the field. By examining isoforms of this enzyme in polyacrylamide gel electrophoresis, we have been able to show different SOD profiles in six common species of Heterodera (H. avenae, H. cruciferae, H. glycines, H. goettingiana, H. schachtii and H. trifolii). The method is quick and therefore lends itself to routine use in a diagnostic laboratory.
The effect of plant age and infection with virus yellows on the survival ofMyzus persicaeon sugar beet
Authors: KIFT N B , DEWAR A M , WERKER A R , DIXON A F G 
Published: February 2008

Summary.Survival ofMyzus persicaeconfined in clip‐cages on mature leaves of sugar beet declined as the plants aged. Death of aphids was often preceded by the appearance of a black deposit in the aphids' stomachs, which may have been the cause of death. Both the rate of death and the proportion of aphids dying with black deposits was significantly less when plants were infected with beet yellows virus or beet mild yellowing virus, by comparison with healthy plants. The implication of these phenomena on the onset of mature plant resistance is discussed.
Development of two spotted spider mite (Acari: Tetranychidae) populations on strawberry and raspberry cultivars
Authors: SONNEVELD T. , WAINWRIGHT H. , LABUSCHAGNE L. 
Published: February 2008

Summary.Five strawberry (Fragaria sp.) and five raspberry (Rubus ideaus L.) cultivars were evaluated for resistance to two spotted spider mite (Tetranychus urticae Koch.). Two methods of assessing the development of two spotted mite populations using detached leaves were compared. The number of eggs laid and mites which developed were compared. The strawberry cvs Hapil and Pegasus had significantly greater development of two spotted mite populations than the cvs Rhapsody, Symphony and Elsanta. The raspberry cv. Joan Squires had higher populations of two spotted mite whilst the raspberry cv. Leo the least, when compared with cvs Glen Clova, Glen Moy and Glen Prosen. Differences were observed in oviposition sites and mite distribution when comparing raspberries with strawberries. The method of assessing the populations development of two spotted mite which involved maintaining the cut leaf stem in water may be of potential use for studying population dynamics of both two spotted mite and possible predators over extended periods of time.
Incidence of fungal species associated with leaf rot disease of coconut palms in relation to weather and the stage of lesion development
Authors: SRINIVASAN N. , GUNASEKARAN M. 
Published: February 2008

Summary.Leaf rot disease (LRD) of coconut occurs in Kerala State, India, and is generally severe during the monsoon, a time of high rainfall and r.h. and low maximum temperature. The pathogenic fungi Colletotrichum gloeosporioides, Exserohilum rostratum, Gliocladium vermoeseni, Fusarium solani, F. moniliforme var. intermedium, Thielaviopsis paradoxa and Rhizoctonia solani were among 14 species isolated from spindles of palms with LRD in multiple samplings of two experiments, each lasting 1 year. Co‐occurrence of fungi was observed in 70–76% of spindles although leaf pieces yielded mostly individual fungi irrespective of the stage of lesion development. C. gloeosporioides occurred most frequently on early lesions. The incidence of C. gloeosporioides was most strongly correlated with rainfall and r.h. and, negatively, with maximum temperature and hours of sunshine. It was the fungus isolated most commonly during the monsoon and occurred on early lesions more frequently than on advanced lesions (determined in one experiment). C. gloeosporioides is thus implicated as the principal pathogen involved in initiation of the disease during monsoons. Its relatively low incidence in the dry season suggests a quiescent phase between periods of parasitic activity. E. rostratum was isolated less frequently and its incidence was less strongly or consistently correlated with weather or with the stage of lesion development. Fusarium spp. and R. solani were associated with dryer weather and higher temperatures. The Fusarium spp. were the fungi isolated most commonly during part of the dry season (January‐March) and occurred more on early than on advanced lesions at one sample (January) when they may have been primary disease agents. R. solani was also more frequent on advanced lesions and may be principally a secondary coloniser of established lesions. The incidence of other fungi, which occurred less frequently and more sporadically, was not associated with weather or consistently with different stages of lesion development.