bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stay‐green compared with non‐stay‐green Lolium perenne in field swards with different cutting and nitrogen treatments
Authors: WILMAN D , IRIANNI RAM , HUMPHREYS M O 
Published: July 2006

SummaryThe purpose of this study was to investigate the effect of the stay‐green trait, originally introduced into perennial ryegrass (Lolium perenne) for amenity purposes, in field swards of stay‐green forage perennial ryegrass managed in different ways for agricultural use. The experimental treatments comprised all 18 combinations of two grass selections (stay‐green and non‐stay‐green), three intervals between cuts and three N treatments. The conclusions were that the introduction of the stay‐green trait (1) may not always confer greater greenness in the early life of a sward; (2) may confer greater greenness during leaf senescence more because carotenoids are unmasked to a lesser extent than because of a reduction in the length of leaf visibly senescing; (3) may reduce herbage yield, particularly when a long interval is allowed between defoliations; (4) may reduce the decline in the concentration of N in herbage during the latter part of a long period of regrowth; (5) may reduce the concentration of Na in herbage.
Aerated hydration treatment for improved germination and seedling growth in aubergine (Solarium melongena) and pepper (Capsicum annuum)
Authors: DEMIR I , OKCU G 
Published: July 2006

SummaryAerated hydration treatment of aubergine and pepper seeds at 25°C (42 h for aubergine, 48 h for pepper) followed by drying increased percent germination across a range of test temperatures (18°C, 25°C and 35°C). The increase in germination obtained by the treatment was retained in storage for up to 4 months. In a glasshouse experiment, aerated hydration decreased mean emergence time but increased seedling dry weight in both species and decreased the proportion of abnormal seedlings in pepper. This work suggests that aerated hydration treatment can improve establishment of these crops in a range of planting temperatures.
Drought effects on the dynamics of leaf production and senescence in field‐grown Medicago arborea and Medicago citrina
Authors: LEFI E , GULÍAS J , CIFRE J , BEN YOUNES M , MEDRANO H 
Published: July 2006

SummaryForage shrub production in the Mediterranean region is frequently limited by soil water availability. To study plant responses to water deficit under such conditions is important for improving crop management and for selecting better yielding forage shrub species. Pre‐dawn leaf water potential (Ψpd), plant leaf area (PLA), leaf area per stem (LAs), leaf appearance rate (LAR1;), leaf senescence rate (LSR), individual leaf area (LA) and maximal leaf elongation rate (LER) were studied throughout the year for Medicago arborea (MA) and Medicago citrina (MC) under irrigated (control) and low rainfall field conditions, at the experimental field site of the University of the Balearic Islands in Spain.With irrigation, the highest LA and LER were observed in autumn and spring and the lowest in winter and summer. LAR; was similar for both species in autumn and winter. Throughout the spring, LAR1 was higher for MC compared to MA. PLA was similar for both species during the autumn, winter and spring seasons; however, during the summer PLA of MA was significantly reduced by 53%. This decline was attributed to higher leaf senescence during seed maturity. As a consequence, MC maintained higher leaf area (∼ 5 m2 plant−1) than MA (3 m2 plant−1).Under natural field conditions, soil water deficit increased from February to late August. The main effect of water stress was a marked reduction in LAR1, LA and LER reflected in lower LAs and PLA. Leaf area was severely reduced for both species during the summer, but much more intensively in MA, which developed full leaf senescence. Thus, MC maintained higher PLA than MA (0.5 m2 compared to 0.0 m2). Throughout the year, but especially in the driest months, MC was superior to MA in leaf growth parameters and PLA.
Production of Phytophthora infestans oospores in planta and inoculum potential of in vitro produced oospores under temperate highlands and subtropical plains of India
Authors: SINGH B P , GUPTA JHILMIL , ROY S , RANA D K 
Published: July 2006

SummaryHigh moisture content of the host tissue ( 88%) and low ambient r.h. (50‐54%) favoured oospore formation under controlled environments. It took 14–16 days for oospores to develop; thereafter the number of oospores increased with time and decreased with moisture content of host tissue. High ambient r.h. (> 80%) did not favour oospore formation under field or controlled conditions. Oospore formation was detected in inoculated plants grown in the field when the ambient r.h. declined to 74% and moisture content of host tissue decreased to 83.7–85.6%. It took 8 days (cv. Kufri Chandramukhi) to 13 days (cv. Kufri Jyoti and Kufri Badshah) for oospores to develop. Cultivars also differed in their response to oospore production, cv. Kufri Chandramukhi being more responsive (4800 oospores g−1 f wt) than cv. Kufri Jyoti and Kufri Badshah (1320 and 390 oospores g−1 f wt respectively). Oospores produced in vitro remained viable when buried in soil in the temperate highlands of Himachal Pradesh and sub‐tropical plains of Uttar Pradesh, India for more than 150 days, i.e. beginning of the next crop season. The oospores germinated and initiated late blight infection at the base of the stems after 21–30 days of incubation of the potato plants raised in oospore‐infested soil. It took 2 days for newly formed oospores to germinate and this delay time increased to 75–77 days after 180‐days burial. It took 15 days for their germination (47%) in soil extract as compared to 50 days in sterilised distilled water.
A mechanical investigation of the retting process in dew‐retted hemp (Cannabis sativa)
Authors: BOOTH I , GOODMAN A M , GRISHANOV S A , HARWOOD R J 
Published: July 2006

SummaryHemp (Cannabis sativa) produces phloem fibres, which are formed in bundles towards the periphery of the stem. This study investigated one aspect of the retting process, the dissociation of these fibres from the core of the stem, which is influenced by the action of micro‐organisms.Peel tests were used to investigate the work required to remove a tissue peel, rich in fibres, from the core of the stem. Two separate experiments studied (1) the effects of tissue dehydration as stems were dried out in the oven; and (2) the progress of retting in stems that were dew‐retted in the field. A comparison between two different types of peel tests, where the stems were clamped either vertically or horizontally in the jaws of a tensile testing machine and the load applied vertically, showed that the work required to peel stems in the vertical position was over 20% greater than that for the horizontal position.Freshly harvested stems were dehydrated in an oven at 40°C over a period of 42 h and as the moisture content decreased there was a significant increase in the work to peel. In contrast, stems that had been dew‐retted in the field showed a significant decrease in work to peel. When the moisture content of stems dried in the oven decreased below 12%, the work to peel rapidly decreased.As the plant tissues dehydrated their fracture characteristics changed and this was reflected in the increase in the work to peel seen in the oven‐dried samples. This, however, was not evident in the field‐retted samples, in which there was a decrease in work to peel. The field‐retted samples were exposed to the activity of micro‐organisms for a prolonged period of time compared with the oven‐dried samples; this increased the potential degradation caused by microbial enzymes. Thus, the reduced work to peel in dew‐retted stems is thought to be due to the colonisation of the stem by micro‐organisms and the subsequent retting process. The dramatic decrease in work to peel at low moisture content in the oven‐dried stems is thought to result from mechanical changes leading to brittle fracture characteristics.This study indicates that peel tests can be used to objectively monitor the reduction in work to peel for dew‐retted stems and relate this reduction to the progress of retting. Thus, peel tests may be used to monitor the effects of different factors on the process of retting in hemp.
Soil fumigation and oxamyl drip applications for nematode and insect control in vegetable plasticulture
Authors: DESAEGER J , CSINOS A , TIMPER P , HAMMES G , SEEBOLD K 
Published: July 2006

SummaryA series of experiments were conducted to evaluate the effect of oxamyl in combination with the soil fumigants 1,3‐D, metam sodium and methyl bromide on nematode damage and fruit yield in vegetables. Experiments were conducted in Tifton, GA, USA over five seasons, between 2000 and 2002, using four different vegetables: squash (Cucurbita pepo), cucumber (Cucumis sativus), pepper (Capsicum annuum) and eggplant (Solanum melongend). In the eggplant experiment, insect populations were monitored. Soil fumigation alone, irrespective of application method or formulation, gave acceptable control of root‐knot nematode in all experiments, except in the spring 2001 pepper experiment. Oxamyl by itself did not provide control of root‐knot nematode (Meloidogyne incognita), but insect populations on eggplant were reduced. Out of three experiments that included oxamyl by itself, root galling caused by Meloidogyne spp. was reduced only on eggplant when nematode pressure was low (five nematodes per 150 cm3 soil). When oxamyl was applied in combination with pre‐plant soil fumigation, small but consistent reductions in root galling were observed. Greatest reductions in galling due to oxamyl were found when fumigation provided less than optimal nematode control. The timing of application of oxamyl did not have much impact on nematode infection, but applications early in the season, preferably starting at planting, appear to be beneficial. Stubby root nematode (Paratrichodorus spp.) populations were low and variable in most experiments, but neither fumigation nor post‐plant nematicide applications seemed to have any effect on soil populations at harvest. Crop yields were often significantly greater when oxamyl followed fumigation, as compared to fumigation only, which could be due to a reduction in root‐knot nematode damage (and in the case of eggplant also reduced foliar damage by insects), and/or to a carbamate growth stimulant response. These experiments indicate the potential of oxamyl to reduce root‐knot nematode infection and increase yields of vegetables when combined with soil fumigation by 1,3‐D and/or metam sodium. More research is required to understand the effect of crop type, pest pressure, preceding fumigant (1,3‐D or metam sodium) and injection timing of oxamyl.
Relationship between canopy reflectance and yield loss due to disease in barley
Authors: NEWTON A C , HACKETT C A , LOWE R , WALE S J 
Published: July 2006

SummaryReflectance from barley field trial plots was measured to determine whether it could be used as an accurate estimate of disease and yield response to fungicide, and whether this was consistent over a range of agronomic factors. Three trials were used to test the effects of cultivar, assessment date, fungicide and dose, different disease and fertiliser. Correlations with predominant disease and resulting yield loss were high, often better than visual disease or green leaf area measurements alone. Certain ratios of two reflectance wavelength measurements were more robust predictors than single wavelengths. Cultivar and development stage had a large influence on measurements and calibration for such morphology‐based characters would be essential for practical deployment. Whilst weather conditions and solar angle restrict opportunities for usage of reflectance tools such as the‘Cropscan Radiometer', it may prove useful in crop loss assessments as an additional objective tool.
The cassava mosaic geminiviruses occurring in Uganda following the 1990s epidemic of severe cassava mosaic disease
Authors: SSERUWAGI P , REY M E C , BROWN J K , LEGG J P 
Published: July 2006

SummaryThe cassava mosaic geminiviruses (CMGs) isolated from cassava plants expressing mild and severe symptoms of cassava mosaic disease (CMD) in 2002 in Uganda were investigated using the polymerase chain reaction and restriction fragment length polymorphism (PCR‐RFLP) molecular techniques and DNA sequencing. Two previously described cassava mosaic geminiviruses: African cassava mosaic virus (ACMV) said East African cassava mosaic virus ‐ Uganda variant (EACMV‐UG2) were detected in Uganda. The RFLP technique distinguished two polymorphic variants of ACMV (ACMV‐UG1 and ACMV‐UG2) and three of EACMV‐UG2 (EACMV‐UG2[1], EACMV‐UG2[2] and EACMV‐UG2[3]). ACMV‐UG1 produced the fragments predicted for the published sequences of ACMV‐[KE]/UGMld/ UGSvr, while ACMV‐UG2, which produced the RFLP fragments predicted for the West African ACMV isolates ACMV‐[NG], ACMV‐[CM], ACMV‐[CM/DO2] and ACMV‐[CI], was shown to be ACMV‐UGMld/UGSvr after DNA sequencing. EACMV‐UG2[1] produced the RFLP fragments predicted for the published sequences of EACMV‐UG2/UG2Mld/UG2Svr. However, both EACMV‐UG2[2] and EACMV‐UG2[3], which produced East African cassava mosaic vzras‐[Tanzania]‐like polymorphic fragments with RFLP analysis, were confirmed to be isolates of EACMV‐UG2 after DNA sequencing. Thus, this study emphasises the importance of DNA sequence analysis for the identification of CMG isolates. EACMV‐UG2 was the predominant virus and occurred in all the surveyed regions. It was detected in 73% of the severely and 53% of the mildly diseased plants, while ACMV was less widespread and occurred most frequently in the mildly diseased plants (in 27% of these plants). Mixed infections of ACMV and EACMV‐UG2 were detected in only 18% of the field samples. Unlike previously reported results the mixed infection occurred almost equally in plants exhibiting mild or severe disease symptoms (21% and 16%, respectively). The increasing frequency of mild forms of EACMV‐UG2 together with the continued occurrence of severe forms in the field warrants further studies of virus‐virus and virus‐host interactions.
Relationship between water‐soluble Ca and other elements and bitter pit occurrence in ‘Idared’ apples: a multivariate approach
Authors: PAVICIC NIKOLA , JEMRIC TOMISLAV , KURTANJEK ZELIMIR , COSIC TOMISLAV , PAVLOVIC IVO , BLASKOVIC DRAZEN 
Published: July 2006

SummaryThe mineral composition of sound fruits of Idared apple and those with symptoms of bitter pit was investigated at two sites on M9 rootstock (Sites 1 and 2) and two sites on MM 106 rootstock (Sites 3 and 4). Concentrations of N, P, K, Ca and Mg were measured. Mg and Ca concentration were determined in water soluble (WS) and water‐insoluble (WI) fractions. The sum of these fractions was regarded as the total concentration (T). At all four sites, Ca (WS) was significantly higher in sound fruit. Principal component analysis (PCA) of data from individual locations showed that the first PCA component accounted for a high proportion of total variance (85% and 70% for Sites 1 and 2 and 70% and 69% for Sites 3 and 4, respectively). Projections of the samples into the planes of the first two PCA components revealed exact classification of the bitter pit status for all samples. The projections revealed that the first PCA component was essential for classification of the status. Determination of the distribution of components of the first PCA indicated that deficiency of water soluble Ca was the most significant factor related to development of bitter pit in ‘Idared’ apples.
Analysing spatial patterns of spread of Lettuce necrotic yellows virus and lettuce big‐vein disease in lettuce field plantings
Authors: COUTTS B A , THOMAS‐CARROLL M L , JONES R A C 
Published: July 2006

SummarySpatial patterns of spread of lettuce big‐vein disease (LBVD) and Lettuce necrotic yellows virus (LNYV) were examined in two plantings each consisting of two blocks of lettuce. LBVD came from planting land infested with viruliferous Olpidium brassicae resting spores, while LNYV was introduced by aphid vectors from external sources consisting of LNYV‐infected sowthistle (Sonchus oleraceus) weeds. Clustering of LBVD was obvious in an area where the soil was heavily infested with only sporadic occurrence elsewhere. There was a steep decline in LNYV incidence over distance from a concentrated external weed source, with clustering of LNYV‐infected plants at the crop edge closest to it. There was no evidence of secondary spread with LBVD or LNYV.
Response of Acroptilon repens to simulated herbivory and soil disturbance
Authors: Kolören O. , Uygur S. , Uygur F.N. , Schaffner U. 
Published: July 2006

Abstract Acroptilon repens is an invasive weed in North America but also causes problems in disturbed habitats in its native range in Asia. In order to test the effect of simulated biological control and soil disturbance on established A. repens patches and the competing vegetation, two levels of shoot clipping as well as soil tillage were imposed on A. repens patches in an undisturbed meadow and at two fallowland sites in the native range of the weed. At the meadow site, 2 years of partial clipping of shoots and of soil tillage had no influence on A. repens performance, while soil tillage significantly reduced the above‐ground biomass of the competing vegetation. At the fallowland sites, which had been continuously cultivated for several years prior to the experiment, A. repens shoot density, biomass and number of seed heads were significantly higher in the undisturbed control than in the tillage plots. The total number of seed heads per unit area increased with shoot density up to 200 shoots m−2. These results indicate that A. repens has considerable regrowth capacities that allow established patches to tolerate substantial losses of above‐ground biomass and that the competitive ability of A. repens is favoured both when soil disturbance is imposed on previously undisturbed sites, as well as when repeated soil disturbance is abandoned. The only promising nonchemical herbicide‐based approach to reduce the competitive ability and seed output of A. repens appears to be a long‐term management that enhances the interspecific plant competition by reducing soil disturbance and selectively damaging A. repens.
Resistance to Tobacco mosaic virus and Botrytis cinerea in tobacco transformed with complementary DNA encoding an inhibitor of viral replication‐like protein
Authors: Akad A. , Teverovsky E. , Gidoni Elad D., Y. , Kirshner B. , Rav‐David D. , Czosnek H. , Loebenstein G. 
Published: July 2006

AbstractWe have previously cloned a 1016‐bp‐long complementary DNA (cDNA) clone (named NC330) encoding an inhibitor of virus replication (IVR)‐like protein from induced‐resistant leaves of Nicotiana tabacum cv. Samsun NN. In the present work, NC330 cDNA was cloned in an Agrobacterium binary vector and introduced into the genome of N. tabacum cv. Samsun nn that is susceptible to Tobacco mosaic virus (TMV). Eight R0 were highly resistant, with TMV titres less than 2% of the controls. The progeny of these primary transformants resulted in four TMV‐resistant and four susceptible lines. The progeny of the plant with highest resistance for TMV was selfed during four generations. In the R2 generation, out of 112 plants tested, 3 plants showed excellent resistance and 5 a lesser degree of resistance. NC330 transcripts were detected in these R2 plants as well as in their R1 and R0 parents. Two R2 plants were self‐pollinated to obtain the R3 generation. All the 25 R3 progeny plants of one line contained PCR‐amplifiable NC330, compared with only 6 of the 23 progeny plants from the other line. Following TMV inoculation, virus was undetectable in seven of the eight tested R3 progeny of the first line and five of the six R3 progeny plants of the second line. NC330 transcripts were detected in the TMV‐resistant transgenic plants but also in some susceptible plants. TMV resistance was suppressed when the plants were kept at higher temperatures (32–34°C), whereas returning the plants to lower temperatures (24–26°C) restored resistance. Transgenic plants resistant to TMV were also resistant to B. cinerea following inoculation of seedlings or of whole plants. The presence of the NC330 DNA was correlated with changes in the physiology of the transgenic plant. Seed germination was inhibited at high temperatures and in the dark. Rootlets of germinating seeds of the transgenic plants grew significantly faster than those of control seeds. These observations were correlated with a significantly higher concentration of abscisic acid in the seeds and seedlings of the transgenic plants. In silico analysis suggests that the NC330 protein translated from the NC330 cDNA is a tetratricopeptide repeats protein and that it may be involved in protein–protein interaction as part of the pathogen resistance mechanism.
Modelling the effect of soil moisture on germination and emergence of wheat and sugar beet with the minimum number of parameters
Authors: Rinaldi M. , Di Paolo E. , Richter G.M. , Payne R.W. 
Published: July 2006

AbstractSoil moisture and temperature, sowing depth and penetration resistance affect the time and percentage of seedling emergence, which are crucial for the simulation of drought‐limited crop production. The aim of this research was to measure the effect of soil water potential on germination and emergence, shoot and root elongation rates (SER and RER) of two different seed/crop types. Sugar beet and durum wheat seeds were sown into two soils (clay and loam), submitted to five matric potentials (−0.01, −0.1, −0.2, −0.4 and −0.8 MPa) and incubated at constant temperature (25°C) and humidity. Cumulative count analysis was used to estimate parameters of the distribution of germination or emergence times for each box of beet or wheat seeds and to derive estimates for base potentials (ψb), hydrothermal times (H) and numbers of viable units. In a second experiment, NaCl solution was used to mimic the soil matric potentials to estimate potential RER and SER. Germination of sugar beet was slightly more sensitive to matric potential than durum wheat (ψb of −1.13 and −1.23 MPa, respectively). H(g) was longer for sugar beet than for durum wheat (67 vs 47 MPa °Cd). For emergence ψb was similar for both seed types and soils but hydrothermal times (H(e)) were 40 MPa °Cd higher for sugar beet than for wheat. Emergence was about 20 MPa °Cd earlier in loam than in clay. SER measured in soils were similar for both crops and for durum wheat it agreed with those determined in NaCl solution. RER and SER fell with decreasing osmotic potential to approximately 20% of their maximum values (1.03 mm h−1 and 0.57 mm h−1, respectively). Seedling viability decreased with decreasing matric potential and more in clay than in loam soil and more for sugar beet than durum wheat. Seed and soil aggregate size are discussed with respect to the effects of water diffusion and soil–seed contact on germination and emergence modelling.