Comparative susceptibility of some potato cultivars to dry rot caused byFusarium sulphureum andF. solani var.coeruleum     

R. L. Wastie  Helen E. Stewart  J. Brown 《Potato Research》1989,32(1):49-55

Summary The susceptibility of 15 potato cultivars to dry rot caused byFusarium sulphureum andf. solani var.coeruleum was examined over 8 years. Tubers were wounded, inoculated, incubated at 10°C for 7–8 weeks and the size of the rot assessed.F. sulphureum was the more aggressive species. There was little correlation between the rank order of susceptibility of the cultivars to the two pathogens, but a higly significant correlation between years. Two years' tests are deemed sufficient to assess susceptibility to both species.  相似文献   

Cellulose and calcium lower the incidence of chemically-induced colon tumors in rats     

Ranhotra GS  Gelroth JA  Glaser BK  Schoening P  Brown SE 《Plant foods for human nutrition (Dordrecht, Netherlands)》1999,54(4):295-303

In a 30-week preliminary study and a follow-up 22-week study (2 × 2 factorial), dimethylhydrazine (DMH)injections effectively induced colon tumors in Fischer-344rats. How this incidence of colon tumors might be affected by cellulose (preliminary study) or by calcium and folic acid (follow-up study) was examined. Cellulose in the dietappeared to provide some protection against DMH-induced colon tumors, but the protective effect of calcium was moreevident; normal levels of calcium (500 mg per 100 g diet), but not of folic acid (0.1 mg per 100 g diet), provided protection against colon tumors. The effect due to calciumwas observed whether viewed in terms of total number of tumors (p lt 0.01) or number of tumors per tumor-bearing rat(p < 0.01).  相似文献   

Use of rescue pollination to make a complex interspecific cross in potato     

C. R. Brown  K. D. Adiwilaga 《American Journal of Potato Research》1991,68(12):813-820

A cross between cultivated tetraploid potato and 2n-pollen producing triploid hybrids containingSolomon stoloniferum genomes was not successful using standard crossing procedures. Berry formation did not occur. Berries were formed, however, when pollination by the triploid hybrids was followed by application of cultivated tetraploid pollen. Berries contained seeds, most of which were intraspecific hybrids of 4x-4x origin. About 4% of 1749 seedlings scored with an isozyme marker were identified as interspecific hybrids of 4x-3x origin. The use of this second pollination is called “rescue pollination.” It appears to promote normal fruit development which standard crossing technique failed to do.  相似文献   

Features and applications of a field imaging chlorophyll fluorometer to measure stress in agricultural plants     

Linn  Alexander I.  Zeller  Alexander K.  Pfündel  Erhard E.  Gerhards  Roland 《Precision Agriculture》2021,22(3):947-963

Most non-destructive methods for plant stress detection do not measure the primary stress response but reactions of processes downstream of primary events. For instance, the chlorophyll fluorescence ratio F_v/F_m, which indicates the maximum quantum yield of photosystem II, can be employed to monitor stress originating elsewhere in the plant cell. This article describes the properties of a sensor to quantify herbicide and pathogen stress in agricultural plants for field applications by the F_v/F_m parameter. This dedicated sensor is highly mobile and measures images of pulse amplitude modulated (PAM) chlorophyll fluorescence. Special physical properties of the sensor are reported, and the range of its field applications is defined. In addition, detection of herbicide resistant weeds by employing an F_v/F_m-based classifier is described. The PAM-imaging sensor introduced here can provide in-field estimation of herbicide sensitivity in crops and weeds after herbicide treatment before any damage becomes visible. Limitations of the system and the use of a classifier to differentiate between stressed and non-stressed plants based on sensor data are presented. It is concluded that stress detection by the F_v/F_m parameter is suitable as an expert tool for decision making in crop management.

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Applications and limitations of tea extract as a virucidal agent to assess the role of phage predation in soils   总被引：1，自引：0，他引：1  

Kaitlin R. Helsley  Theresa M. Brown  Kevin Furlong  Kurt E. Williamson 《Biology and Fertility of Soils》2014,50(2):263-274

In marine ecosystems, phage predation (phage-mediated cell lysis) is an important driver of bacterial mortality through host cell death and nutrient cycling through the release of cell contents. Both of these impacts increase marine microbial diversity by increasing interspecific competition. By contrast, very little is known about the role of phage predation in terrestrial ecosystems. A recent field study in Barrow, AK found phage predation to be a key factor controlling terrestrial bacterial population dynamics in Arctic soils. When phage abundance was artificially reduced using a tea extract, antiphage treatment, bacterial abundance, and respiration increased accordingly, suggesting top-down control by phages. The goal of this study was to examine the impact of phage predation in temperate soil ecosystems. Laboratory-scale experiments confirmed the potent antiphage properties of tea extracts. However, field experiments conducted at two discrete sites (upland and wetland) yielded little evidence that top-down control by phage predation was significant in temperate soils.  相似文献   

Variation of trace element accumulation by iron-manganese nodules from Dystric Cambisols with and without contamination     

Timofeeva  Yana O.  Karabtsov  Alexander  Ushkova  Maria  Burdukovskii  Maxim  Semal  Victoria 《Journal of Soils and Sediments》2021,21(2):1064-1078

Journal of Soils and Sediments - The aim of this study was to characterize the influence of soil contamination on the trace element accumulation in nodules, inter-element relationships inside the...  相似文献   

酶混合物添加剂对生长猪养分回肠和粪便消化率的影响     

Ji F Casper D P Brown P K Spangler D A Haydon K D Pettigrew J E 《饲料博览》2008,(9):39-39

试验旨在测定β-葡聚糖酶和蛋白酶的混合物（EBP）对生长猪粪消化率（FD）、表观回肠消化率（AID）、标准回肠消化率和后肠消化率的影响。12头安装回肠瘘管的生长阉公猪,体重为（38．2±0．5）kg,单独饲养在代谢箱中,按照先前的饲料摄入量编号到3个组中,每组4头。试验采用4×4拉丁方设计,试猪随机分配到每组（方）3个重复的4个处理中。处理分别为基础饲粮（基础）,基础＋0．05％EBP（0．05％EBP）,基础＋0．10％EBP（0．10％EBP）及水解酪蛋白,水解酪蛋白用以测定内源氨基酸。基础饲粮含玉米和豆粕,其营养水平计算值分别为代谢能3．36Meal·kg^-1,总赖氨酸1．1％。在第一阶段,拉丁方的每个重复的饲粮采食量是预试阶段4头试猪最小饲料采食量的85％,且每组相等。每个继发阶段饲养水平提高100g·d^-1。每个试验阶段14d,其中饲粮适应期4d,粪便收集期5d、过渡期3d和回肠收集期2d。每天间隔12h连续收集回肠流出物。与栗食基础饲粮的猪相比。采食EBP的猪干物质（DM）、有机物（OM）、能量、粗蛋白（CP）、非纤维性碳水化合物、总饲粮纤维、不溶饲粮纤维、酸水解脂肪、灰分、钙（Ca）和磷（P）的FD显著升高（P〈0．05）。饲粮中添加EBP0．05％或0．10％,试猪中性洗荆纤维（NDF）和半纤维素的AID显著升高（P〈0．05）,但是DM和能量的AID没有增加。与采食基础饲粮的试猪相比,采食EBP的试猪酸水解脂肪的AID趋向于升高（P〈O．051）。各处理间多数氨基酸的回肠消化率没有显著差异,但是EBP显著降低蛋氨酸、丙氨酸和丝氨酸的表观、标准消化率（P〈0．05））。与采食基础饲粮的试猪相比,采食EBP的试猪半纤维素的FD与AID的差异显著减小（P〈0．05）。结果显示,生长猪采食EBP能改善DM、OM、能量、CP、非纤维碳水化合物、总饲粮纤维?  相似文献   

Survival and growth of upland oak and co-occurring competitor seedlings following single and repeated prescribed fires     

Heather D. Alexander  Mary A. Arthur  David L. Loftis  Stephanie R. Green 《Forest Ecology and Management》2008

Studies within and outside the U.S. indicate recurring oak (Quercus spp.) regeneration problems. In deciduous forests of the eastern U.S., a prevailing explanation for this trend is fire suppression leading to high competitor abundance and low understory light. In response, prescribed fire is increasingly used as a management tool to remedy these conditions and encourage future oak establishment and growth. Within eastern Kentucky, we implemented single and repeated (3×) prescribed fires over a 6-yr period (2002–2007). Pre- and post-burn, we quantified canopy cover and oak seedling survival and growth compared to other woody seedlings deemed potential competitors, primarily red maple (Acer rubrum L.) and sassafras (Sassafras albidum (Nutt.) Nees.). Burning temporarily decreased canopy cover 3–10%, but cover rebounded the subsequent growing season. Repeated burning ultimately produced canopy cover about 6% lower than sites unburned and burned once, suggesting a cumulative effect on understory light. Red maple exhibited low survival (∼40%) following single and repeated burns, but growth remained similar to unburned seedlings. Burning had little impact on sassafras survival and led to total height and basal diameters 2× greater than unburned seedlings. A single burn had no impact on red oak (Erythrobalanus spp.) survival and increased height and basal diameters 25–30%, but this positive growth response was driven by seedlings on several plots which experienced high burn temperatures and consequently high overstory mortality. White oaks (Leucobalanus spp.), however, exhibited twice as high mortality compared to those unburned, with no change in growth parameters. Repeated burning negatively impacted survival and growth of both oak groups compared to unburned seedlings. With both burn regimes, oaks with smaller pre-burn basal diameters exhibited the lowest post-burn survival. Thus, despite the ability of prescribed burns to temporarily increase understory light and reduce red maple survival, neither single or repeated burns placed oaks in an improved competitive position. These findings result from a combination of highly variable yet interdependent factors including the (1) life history traits of oaks compared to their co-occurring competitors, (2) pre-burn stature of pre-existing oak seedlings, and (3) variability in fire temperature and effects on understory light.  相似文献   

SAGE transcript profiling of the juvenile cambial region of Eucalyptus grandis     

Gallo de Carvalho MC  Caldas DG  Carneiro RT  Moon DH  Salvatierra GR  Franceschini LM  de Andrade A  Celedon PA  Oda S  Labate CA 《Tree physiology》2008,28(6):905-919

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Comparison of <Emphasis Type="Italic">Pinus taeda</Emphasis> L. whole-tree wood property calibrations using diffuse reflectance near infrared spectra obtained using a variety of sampling options     

P. David Jones  Laurence R. Schimleck  Richard F. Daniels  Alexander Clark III  Robert C. Purnell 《Wood Science and Technology》2008,42(5):385-400

A necessary objective for tree-breeding programs, with a focus on wood quality, is the measurement of wood properties on a whole-tree basis, however, the time and cost involved limits the numbers of trees sampled. Near infrared (NIR) spectroscopy provides an alternative and recently, it has been demonstrated that calibrations based on milled increment cores and whole-tree data can provide good estimates of whole-tree properties. Several options exist for sampling standing trees and the aim of this study was to compare wood property calibrations based on NIR spectra collected from samples obtained using different sampling methods. Calibrations for whole-tree lignin and basic specific gravity based on NIR spectra from whole-tree chips (milled or intact) had the strongest statistics, calibrations based on NIR spectra from milled increment cores were similar. Other options for sampling the tree (drill shavings, etc.) gave errors that were too large for practical applications. If an increment core is going to be used to estimate whole-tree properties, it is recommended that it be dried and milled prior to analysis.  相似文献