Use of enzyme-linked immunosorbent assay to detect potato leafroll virus in field grown potato,cv. Russet Burbank

Use of enzyme-linked immunosorbent assay (ELISA) in detecting potato leafroll infections in field grown potato, cv. Russet Burbank, was studied from 1986 to 1988 at Rosemount, Minnesota. The objective was to determine relative reliability of current season foliage ELISA, tuber tissue ELISA, and tuber progeny foliage ELISA. Serological tests were most accurate when foliage of tuber progenies was tested. ELISA underestimated total leafroll infection when current season foliage from the inoculated plant was used, in those plants inoculated during late tuber bulking stage. Current season foliage ELISA tests using newly expanded terminal leaflets were more reliable than were tests using older leaflets. Leafroll infection was detected in the current season foliage and tuber progenies (tuber tissue as well as tuber progeny foliage) of some plants seven days after inoculation. Most current season foliage infections were detected by day 14–28 depending on year. Differences among years were most likely caused by variation in quality of virus source plants and numbers of vectors used in inoculation. ELISA tests on tuber tissue were almost as effective as ELISA tests on tuber progeny foliage in detecting potato leafroll 20 days after inoculation, but ELISA on tuber tissue substantially underestimated infection if plants were sampled earlier. Maximum percent tuber infection occurred 20 days or more after inoculation. Movement of the virus from the inoculated stem to other stems decreased with increased plant age at inoculation. Percent infected tubers declined with increased plant age at inoculation. Action thresholds developed for aphids in managing potato leafroll virus should take into account the temporal change in percent infected tubers.     

A rapid and simple method for determination of potato chloroplast DNA type

A procedure for restriction enzyme analysis of the potato chloroplast DNA (ctDNA) is described. The advantages of this method are: 1) rapid determination of ctDNA type, 2) no ultracentrifugation, and 3) low cost of analyses. This method makes it easy to distinguish the ctDNA types of wild and cultivated potato accessions.     

Pre and early post-emergence weed control with Paraquat in potatoes

Studies using Paraquat herbicide for early post-emergence control of broadleaved and grass weeds in Katahdin and Russet Burbank potatoes were conducted in Maine during four growing seasons. All rates and times of application of Paraquat gave good commercial control of grass and broadleaf weeds when compared to Premerge and Dowpon treatment as checks. Paraquat applied to Katahdins 2 weeks after ground crack reduced the yield of tubers but did not significantly affect specific gravity. Yield and specific gravity of Russet Burbank was reduced by Paraquat applied one and 2 weeks after ground crack. Paraquat can be used effectively for weed control in Katahdin up to one week after ground crack without crop damage. In Russet Burbank it appeared that application at ground crack was about as late as Paraquat could be applied without affecting yield or specific gravity of tubers.     

Mechanical and rheological properties of calcium carbonate-filled ethylene propylene diene elastomer reinforced by metallic acrylate salt

High performance ethylene propylene diene methylene elastomer (EPDM)/calcium carbonate (CaCO₃)/aluminum triacrylate (ALTA) hybrids have been prepared by a melt compounding process. The mechanical properties of the peroxide cured EPDM/CaCO₃/ALTA vulcanizates were investigated by tensile, hardness, resilience, abrasion and fatigue life tests. The results showed that the ALTA can greatly improve the modulus at 100 %, tensile strength, abrasion resistance and fatigue life of the EPDM/CaCO₃/ALTA vulcanizates, while retaining their high elongation at break. ALTA as a reactive filler had accelerating effect on the vulcanization reaction of and increased the crosslink density of the EPDM/CaCO₃ composites. This phenomenon is due to increasing the ionic bonds arise from both homo-polymerization of ALTA and graft co-polymerization of it onto the EPDM. Scanning electron microscopy (SEM) revealed the presence of ALTA causes to the roughness of the fracture surface of CaCO₃-filled EPDM compounds demonstrating high interaction between the fillers and EPDM improved by introduction of ALTA. Dynamic mechanical analysis revealed that the glass transition temperature (T _g ) and dissipation peak (tan δ) of EPDM composites decreases with increasing ALTA content. Decrease in tan δ value and inward shifting of T _g were related to improved interaction of filler and EPDM.     

Preparation and characterization of glass fiber-coir hybrid composites by a novel and facile Prepreg/Press process

The present study explored the preparation of glass fiber-coir reinforced unsaturated polyester resin hybrid (GCU) composites with a novel Prepreg/Press fabrication process. Flexural, impact and thermal-mechanical properties of GCU composites were investigated. Coir reinforced unsaturated polyester resin (CU) composites was also prepared with the same process to explore the enhancement effect of glass fabric on the mechanical properties of coir-based composites. The effect of fabrication pressure on the mechanical properties of CU and GCU composites was examined. Micromorphology and interfacial reaction of the composites were analyzed. It is shown that GCU composites fabricated with the Prepreg/Press process have excellent flexural strength (185.0 MPa), MOE (18.3 GPa), and impact strength (67.2 kJ/m²). The mechanical properties of GCU composites increased with the increase of applied pressure up to 0.8 MPa in the Prepreg/Press process. However, further increase of applied pressure led to the decrease in mechanical properties. The addition of glass fabrics to GCU composites showed 419 % improvement in flexural strength, 708 % improvement in MOE and 562 % improvement in impact strength over coir-based composites. The micromorphology study proved that the poor interfacial bonding between coir and matrix led to the low mechanical properties of coir-based composites.     

Somerset: A new chipping potato variety

The Somerset potato variety is a medium-maturing variety with attractive, round to oblong, white-skinned, white-fleshed tubers with shallow eyes. Its major use is expected to be as a chipping variety in areas where potatoes are stored for some length of time, since its sugar content is lower than most varieties during storage, and it can be chipped after six months in storage. Somerset does not show the net necrosis caused by potato leafroll virus, and is immune to race 0 of Phytophthora infestans (late blight). Somerset is also moderately resistant to infection by Alternaria solani (early blight), and is only moderately susceptible to Verticillium wilt. Somerset is more susceptible to both common and acid scab than Superior, but less susceptible than Kennebec and Katahdin. It also has shown susceptibility to skinning and shatter bruise, but does not have a strong blackspot bruise reaction.     

Bison,a new red-skinned potato variety

Bison, a new red potato, was introduced by North Dakota State University. This new red variety has smooth tuber type and bright red skin color. Bison yields somewhat less than Norland and Red Pontiac but the advantage of Bison over these two varieties is its uniformity and bright red color. Bison is about medium in total solids and makes chips comparable in color to Norchip but lighter in color than Kennebec. Bison is resistant to race 0 of the late blight organismPhytophthora infestans, but susceptible to race 1–4.     

Pre-harvest chemical applications for control of tuber infection byAlternaria solani

Pre-harvest chemical applications significantly reduced populations of viableAlternaria solani spores on the soil surface in the laboratory and field and the infection of potato tubers in the field. Only formaldehyde consistently reduced spore germination and tuber infection in the laboratory and the field but Difolatan 4F, Difolatan 4F + DMSO (dimethyl-sulfoxide), Manzate D, Manzate D + DMSO and sodium hypochlorite often reduced fungus populations significantly. More work is necessary before pre-harvest chemical applications can be recommended for control of early blight tuber decay due to the variable performance of many chemicals and the relatively high cost and corrosiveness of formaldehyde, the most effective chemical in the study.     

Preparation and thermal properties of polyphenylene sulfide/organic montmorillonite composites

Cetyl trimethyl ammonium bromide (CTAB) was used for the intercalation modification of nano-montmorillonite (MMT). The spectra of Fourier transform infrared spectrometer (FTIR) and X-ray diffraction (XRD) suggested that CTAB had intercalated into the layers of MMT. And the interlayer spacing of MMT increased from 1.198 to 3.616 nm. The thermogravimetric analysis (TGA) curves of organic montmorillonite (OMMT) showed three-step degradation. The scanning electron microscope (SEM) photographs showed that surface morphology of MMT remained unchanged. Then polyphenylene sulfide (PPS)/organic montmorillonite (OMMT) composites were prepared by melt blending. And composites were treated at 180 °C for 24 h. The results of SEM showed that OMMT had good dispersion behavior and adhesion with PPS. The results of differential scanning calorimetry (DSC) showed the addition of OMMT resulted in heterogeneous nucleation crystallization of PPS. The results of TGA showed there was a good improvement of the thermal stability of PPS. The FTIR and color measurement analysis showed the addition of OMMT could improve the thermal oxidation stability.     

Purification of potato virus A and its detection in potato by enzyme-linked immunosorbent assay (ELISA)

Potato virus A (PVA) was purified fromNicandra physaloides by a simple method that omitted organic solvent clarification and consisted of differential centrifugation followed by equilibrium centrifugation in CsCl. An antiserum was produced that specifically detected PVA in potato leaf sap using either the SDS-agar test or enzyme-linked immunosorbent assay (ELISA). No heterlogous reaction of the antiserum with potato virus Y was detected. Purified PVA was highly infectious; it had an A 258/280 nm absorbance ratio of 1.28. The particles had a normal intact appearance in the electron microscope. Detection of PVA in potato sprouts and foliage by ELISA was compared with the local lesion assay onPhysalis angulata L. plants. ELISA was superior over an indicator plant test when sprout tissue was used. PVA antiserum reacted similarly with mild and crinkle isolates.     

Objective methods for testing potato flake quality as influenced by free starch and surfactants

A method was developed which uses changes in rates of retrogradation measured by a Brabender Amylograph to assess the complexing ability of surfactants for free starch in potato flakes during cooling. The rate of retrogradation was linearly related to surfactant concentration. A Blue Value Index method, adapted from use with cereal flours for determination of starch damage, was used to monitor the amount of free starch created by the required particle size reduction for Amylograph analysis. The change in Blue Value Index was also used to monitor the ability of surfactants to complex free starch and thereby influence potato flake quality. Distilled monoglyceride appeared to be more effective than sodiumor calcium stearoyl–2-lactylate. However, the combination of 0.3% distilled monoglyceride with 0.2% sodium stearoyl–2-lactylate was nearly as effective as 0.5% distilled monoglyceride in terms of free starch complexing ability. Instron back extrusion tests for mealiness of reconstituted flakes were found to be influenced by the level of free starch; therefore, back extrusion data should be accompanied by Blue Value Index data.     

A rapid method for determining blackspot susceptibility of potato clones

Two methods of determining susceptibility of potato clones to blackspot were compared: (1) bruising by weight dropping and (2) bruising by abrasive peeling. A highly significant positive correlation was obtained between the intensity of enzymatic discoloration following abrasive peeling and the amount of blackspot that developed by weight dropping (r=0.93). Abrasive peeling was more rapid than the weight-dropping method. Tuber samples were abraded 30 sec and the amount of enzymatic discoloration evaluated after 24 hr. The need for individually bruising and hand peeling of tubers was eliminated with this method. Because of the rapidity of the abrasive peeling method, it can be used effectively in potato breeding programs to screen large numbers of clones for blackspot susceptibility. Results indicate that tuber maturity affects enzymatic discoloration and blackspot susceptibility. Immature tubers, dug while the vines are still green, are more resistant to blackspot than mature tubers. Tuber maturity therefore must be considered when screening clones for susceptibility to blackspot.     

Redsen: A new bright red-skinned potato cultivar

Redsen is a smooth, round, bright red-skinned potato cultivar with medium to high yield potential. It has resistance to race 0 of late blight (Phytophthora infestons) and is moderately resistant to some strains of silver scurf (Helminthosporium solanum) and common scab (Streptomyces scabies). The red color resists fading during storage and Redsen retains excellent marketability during storage.     

Effect of temperature on the sugar content of potato callus tissue

The effects of temperature, incubation time, callus age, and growth regulator on the reducing and nonreducing sugars of Lemhi Russet callus grown on Murashige - Skoog medium with 3% sucrose were determined. Callus grown at 25°C for approximately 4 weeks (0 time) were held at 25°C or transferred to 15°C and 5°C for 4-week periods. Callus grown at 5°C for 4 weeks was transferred back to 25°C for a 4-week period to simulate reconditioning of potatoes. The reducing sugar content decreased rapidly with time at 25°C and 15°C when either 2,4-D or picloram was used as a growth regulator. At 5°C the reducing sugar content increased or decreased slightly, depending on the original reducing sugar content of the callus. The initial reducing sugar content at 25°C and the relative effect of 5°C incubation was dependent on the age of the callus tissue. Reducing sugars in 5°C callus were rapidly lost after reconditioning at 25°C. The nonreducing sugars exhibited similar overall changes as the reducing sugars, but the nonreducing sugar concentrations were much lower. Thus, potato callus cultures are similar to whole tubers insofar as they accumulate or maintain high reducing sugars at low temperatures and lose these sugars during reconditioning.     

Manufacture and performance of O-carboxymethyl chitosan sodium salt/cellulose fibers in N-methylmorpholine-N-oxide system

A series of O-carboxymethyl chitosan sodium salt (NaCMCh) with different degree of substitution (DS) of -CH₂COONa agent were successfully prepared by altering the reaction temperature and time. Both fourier transform infrared spectroscopy (FTIR) and ¹³C-Nuclear Magnetic Resonance (¹³C-NMR) were used to study the structure of NaCMCh. And the impact of DS on the antibacterial activity of NaCMCh was investigated. Then, the NaCMCh with optimal antibacterial activity was selected to prepare NaCMCh/cellulose fibers in N-methylmorpholine-N-oxide (NMMO) system. The structure, crystallization behavior, thermal property and morphology of obtained fibers were carefully studied with FTIR, Wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermal gravimetric (TG) and scanning electron microscope (SEM), respectively. Meanwhile, the antibacterial activity as well as mechanical properties of resultant fibers was also investigated. The results demonstrated that the fibers had strong antibacterial activity against Escherichia coli (E. coli), acceptable mechanical properties and good water retention.     

Haploid induction in Mexican polyploid species and colchicine-doubled derivatives

Haploids (tetraploids and triploids) were obtained from crosses between colchicine-doubled octaploid and natural hexaploid Mexican potato species and the Gp. Phureja clone 1.22 as the pollinator, but none were obtained from crosses of natural 4x(2EBN) Mexican species with 2x(1EBN) pollinators. The manipulation of ploidy and Endosperm Balance Number (EBN) of tetraploid Mexican potato species was useful in explaining the occurrence of pseudogamous parthenogenetic haploid production. The pollinator effect, EBN, and maternal influence are important characters to consider in searching for haploid-inducing pollinators among 2x(2EBN) as well as 2x(1EBN) potato species.     

A study of surface morphology and structure of cotton fibres with soluble immobilized-cellulase treatment

Our previous studies have demonstrated that cotton fabrics treated with soluble immobilized-cellulase showed considerably lower degradation and higher retention of tensile strength than those treated with free cellulase. It is important to investigate the surface morphology and structure of cotton fibres for understanding the enzymatic degradation. In this study, the effects of the soluble immobilized-cellulase on the surface morphology and structure of cotton fibres were investigated. The ultrastructural changes in the fibre surfaces were inspected using Tapping-Mode Atomic Force Microscopy (TM-AFM) and scanning electron microscopy (SEM), and the results showed that the smooth surfaces could be obtained after the immobilized-cellulase treatment, and no obvious damage was observed on the fibre surfaces. The hydrogen bonds in the certain depth area beneath the fibre surface were investigated using Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR) after the cellulase treatments. Furthermore, the result of fibre accessibility indicated that the hydrolysis occurring in the interior of the cotton fibres was limited during the immobilized-cellulase treatment. Crystalline index (CI) of the cotton fibres treated with free cellulase was slightly higher than that of fibres treated with immobilized cellulase.     

Petiole nitrate content of Maine-grown Russet Burbank and Shepody potatoes in response to varying nitrogen rate

Russet Burbank and Shepody potatoes were grown with at-planting nitrogen fertilizer rates varying from 0 to 270 kg ha^?1 following small grains and red clover. Petiole samples were collected from the 4th and 5th leaflets at four to six dates each during the 1986 to 1989 growing seasons. The samples were dried and analyzed for NO ₃ ^? N content. Petiole NO ₃ ^? N levels were strongly related to nitrogen rate regardless of cultivar, growing season, and cropping system. Differences among treatments and NO ₃ ^? N content varied substantially as the growing season progressed with petiole NO ₃ ^? N levels declining rapidly in underfertilized plots as the plants aged. Petiole NO ₃ ^? N levels were higher at midseason following red clover than following small grains. Sampling 50 to 60 days after planting (DAP) is most appropriate as a tool for scheduling supplemental nitrogen applications. At 50 DAP, critical petiole NO ₃ ^? N levels were 1.6 and 1.7% for Russet Burbank and Shepody, respectively. Petiole NO ₃ ^? N levels above 2.2% at 50 DAP resulted in lower yields of Russet Burbank than when petiole NO ₃ ^? N levels were in the 1.6 to 2.2% range. Petiole NO ₃ ^? N testing should be particularly useful as a diagnostic tool in management strategies which make maximum use of previous crop residues, organic amendments, and soil reserves as nitrogen sources.