Factors influencing PVY development and disease expression in three potato cultivars

Studies were performed to investigate factors affecting symptom expression of potato virus Y infection in three potato cultivars, Russet Norkotah, Shepody, and Red LaSoda. Quantitative enzyme-linked immunosorbent assay (ELISA) results revealed few differences in the relative virus titer among cultivars tested. Potato virus Y (PVY) titers developed as rapidly in Russet Norkotah as in Shepody and Red LaSoda. Additional studies were performed to determine the effect of light intensity and infections of PVY and potato virus X (PVX), alone and in combination, on the expression of mosaic symptoms in these three cultivars. Low light intensity (270-330 uE/m²/sec) significantly increased plant heights and severity of mosaic disease among the cultivars compared to high light intensity (100-200 uE/m²/sec). PVX and PVY, as well as the combination of PVX and PVY in the same plant, decreased plant height compared to the uninoculated (healthy) controls. Low light intensity and dual infections of PVX and PVY significantly increased mosaic disease severity in Shepody and Red LaSoda, but not in Russet Norkotah. Results of these studies refute the suggestion that Russet Norkotah is resistant to PVY infection since virus titers in this cultivar are similar to the known susceptible cultivars Shepody and Red LaSoda. These results further suggest that while Russet Norkotah is fully susceptible to infection by PVY, it resists symptom expression.     

不同滴灌量对马铃薯产量及品质的影响

滴灌技术在农业生产中对于抗旱具有重要的作用。本文研究了不同滴灌量对马铃薯产量和质量的影响,结果表明,300m·3hm-2处理可显著地提高产量、大中薯率及经济效益,块茎还原糖、Vc和淀粉含量均没有明显变化。该研究为在马铃薯生产上合理应用滴灌技术提供了理论依据。     

Red cloud: A dark red-skinned potato cultivar which holds color in storage

Red Cloud is a midseason potato comparable in maturity to Red LaSoda and later than Red Norland. It is characterized by a thick, dark red skin and white flesh. The red skin coloring holds well in storage, longer than either Red LaSoda or Dark Red Norland. Red Cloud produced above average yields in trials conducted in Nebraska, Colorado, Arizona, and Texas, and in the 14 participating States and Provinces of the North Central Regional Potato (NCR) Trial in 1982. Yields of Red Cloud were higher than Dark Red Norland and lower than Red LaSoda in NE (1989–1991), similar to Red Norland in NE and CO (1977–1982) and to Red LaSoda and Dark Red LaSoda in AZ (1978–1982), and similar to Dark Red Norland and lower than Red LaSoda in TX (1982). Red Cloud tends to have more grade outs due to bulging eyes than the above standards. The specific gravity has been consistently greater than standard and other experimental red cultivars. Red Cloud had fewer tubers with hollow heart or vascular discoloration, and fewer tubers with any internal or external defects than Red Norland and Red Pontiac. It has demonstrated heat tolerance in Arizona. The white flesh has a mealy texture. The primary market for Red Cloud is a fresh table potato for boiling, mashing and baking.     

Winema: An Early Maturing, Red- Skinned Cultivar for Fresh Market

Winema, an early maturing, red-skinned cultivar for fresh market use, was jointly released in 2000 by the Agricultural Experiment Stations of Oregon, North Dakota, California, Idaho, and Washington. Winema was evaluated in irrigated trials in Oregon and California from 1990 to 2000 and in the Western Regional Trial in 1995,1997, and 1998. Winema has produced lower total yields than Dark Red Norland and Red LaSoda at most locations, but similar or higher marketable yields and significantly fewer culls. In 20 location-years of replicated Oregon and California trials, Winema produced 108% and 99% of marketable yields of tubers under 280 g compared with Red LaSoda and Dark Red Norland, respectively. Similarly, in 23 location-years of The Western Regional Trial in 6 western states, Winema produced 109% and 92% of marketable yields of tubers under 280 g compared with Red LaSoda and Dark Red Norland, respectively. Winema tubers are smooth-skinned with shallow eyes. Winema’s bright red color does not fade appreciably in storage. Winema is susceptible to potato virus Y (PVY). Foliar symptoms of PVY are difficult to detect visually.     

Mazama: An Early Maturing, Bright Red-Skinned Cultivar For Fresh Market

Mazama, an early maturing red-skinned cultivar for fresh market use, was jointly released in 2000 by the Agricultural Experiment Stations of Oregon, North Dakota, California, Idaho, and Washington. Mazama was tested in irrigated trials in Oregon from 1990 to 2000 and in the Western Regional Trial in 1994, 1995, and 1997. Mazama produces lower total yields than Dark Red Norland and Red LaSoda, but similar marketable yields with a high percentage of small, high-value tubers and significantly fewer culls. In 22 location-years of replicated Oregon and California trials, Mazama produced 40% and 26% higher marketable yields of U.S. #1s under 280 g than Red LaSoda and Dark Red Norland, respectively. In three years of replicated trials in six western states, Mazama produced 115% and 102% of marketable yields of U.S. #1s under 280 g compared with Red LaSoda and Dark Red Norland, respectively. Mazama tubers are smooth skinned and shallow eyed. Mazama’s bright red color does not fade in storage. Mazama is less susceptible to potato virus Y than Dark Red Norland or Red LaSoda.     

Influence of Growth Regulators on Plant Growth, Yield, and Skin Color of Specialty Potatoes

2,4-D has been used since the 1950’s to enhance color in red-skinned potatoes, but there is little research on the potential use of other plant growth regulators to improve tuber skin color in the wide range of specialty potatoes now available on the market. Field trials conducted at Parma, ID in 2009 and 2010 evaluated the effect of foliar applications of 2,4-D, NAA, and LPE on plant height, foliar injury, tuber yield, size distribution, and skin color of six specialty potato cultivars. Skin color was rated visually and via HunterLab colorimeter at harvest, and again after storage (132 days in 2009 and 93 days in 2010) at 4 °C and 95 % R.H. 2,4-D caused slight foliar injury and reduced tuber size in all cultivars. It also increased visual skin color rating in the red-skinned cultivars ‘Red LaSoda’ and ‘TerraRosa’ at harvest and after storage, and influenced incidence of pink coloration around the eyes of ‘Yukon Gem’ tubers, but did not affect color of blue/purple-skinned cultivars. NAA and LPE did not consistently influence plant growth, yield, tuber size or visual skin color in any cultivar. Colorimetric evaluations mostly agreed with the visual ratings, and indicated that storage significantly altered skin color in all cultivars, regardless of growth regulator treatment.     

不同灌溉方式在马铃薯生产上的应用效果

在田间试验条件下,研究了滴灌技术与传统喷灌技术对马铃薯大薯率和产量的影响,并进行了经济效益分析。试验设3个处理:滴灌区为处理A,常规喷灌区为处理B,不灌溉区(对照)为处理C。结果表明:滴灌区处理能增加马铃薯的大薯率,显著提高马铃薯块茎产量,增幅达46.7%,经济效益提高显著。该研究对滴灌技术在马铃薯生产上的推广和应用具有重要的意义。     

Modoc: A potato variety with bright red skin and early maturity for fresh market

Modoc is an early maturing, red-skinned, whitefleshed potato cultivar for fresh market use. The Agricultural Experiment Stations of Oregon, North Dakota, California, Idaho, and Washington jointly released Modoc in 2003. Modoc was derived from a 1989 cross of ND1196-2R and ND2225-1R performed at North Dakota State University. Modoc retains bright skin color in storage and is suited for marketing directly from the field or storage. It produces slightly lower total yield than Red LaSoda or Dark Red Norland, but higher marketable yield and more desirable tuber size and shape. Modoc tubers seldom exhibit growth cracks, secondary growth, hollow heart or other external or internal defects. Dry matter content of Modoc tubers is similar to Dark Red Norland and Red LaSoda (18.9% compared to 18.8% and 17.7%, respectively). Culinary quality of Modoc was rated equal to Dark Red Norland and Red LaSoda for boiling and microwaving preparation methods. Modoc tubers are similar to standard varieties in sugar, vitamin C, and glycoalkaloid (4.5 mg/100 g) concentration. Modoc foliage clearly expresses PVY symptoms and has not demonstrated high susceptibility to viral or fungal diseases during a decade of seed production and evaluation.     

Assessment of PCR-based simple sequence repeats to fingerprint North American potato cultivars

Seven primer pairs flanking di- and tri-nucleotide repeat sequences, identified from previously sequenced regions of the potato genome, were examined for their potential use in DNA-fingerprinting of thirty-nineSolanum tuberosum subsp. tuberosum cultivars (released between 1861 and 1988) and one diploidS. phureja breeding line. Of the simple sequence repeats (SSRs), the primers for six SSRs amplified DNA sequences within the potato genome between cultivars for a total of 14 bands. The polymerase chain reaction (PCR)based amplification products generated from each primer pair consisted of 1 to 2 bands per cultivar but band variation among cultivars demonstrated up to 4 bands per SSR. A similarity matrix generated from five SSRs was able to distinguish 24 of the 40 cultivars. However, when the potato cultivars were grouped by tuber type (round white-skinned, long white-skinned, russetskinned, red-skinned, and yellow flesh) only five pairs of cultivars remained indistinguishable: Atlantic/Katahdin, Belchip/Wauseon, Red LaSoda/Bliss Triumph, Red Pontiac/Norland, and Burbank/Spunta. Although SSRs did not generate unique fingerprints for all of the North American genotypes examined, the potential to discriminate most cultivars should increase as additional SSRs are identified in potato.     

马铃薯膜下滴灌节水及生产效率的初步研究

为了探索膜下滴灌在马铃薯生产中应用的可行性,于内蒙古达茂旗进行了膜下滴灌试验。结果表明:膜下滴灌比露地滴灌平均增产26%,水分利用效率提高28.5%,灌水的平均生产效率提高26%,因此,膜下滴灌应该成为内蒙古西部地区马铃薯生产中有效的增产节水措施。一带双行滴灌模式下马铃薯平均产量显著高于一带一行处理,这种滴灌模式不仅节约管道设备,而且进一步提高了水分利用效率和灌水生产效率,值得在生产中广泛推广。尽管露地滴灌条件下马铃薯产量与滴灌带的密度有关,一带一行灌溉方式下产量高于一带双行,但总体而言,露地滴灌在水分利用效率上显著低于膜下滴灌,因此在水分不足的内蒙古西部马铃薯产区,不建议广泛推广露地滴灌。     

Is Partial Root-Zone Drying More Appropriate than Drip Irrigation to Save Water in China? A Preliminary Comparative Analysis for Potato Cultivation

China is the largest worldwide potato producer where around half of the crops is planted in the semi-arid region frequently affected by water restriction. While innovative methods are needed for water-saving irrigation methods, the use of low-cost and environmental-friendly technology must be prioritised. In this study, potato production under drip irrigation (DI, commonly adopted to save water) was compared with partial root-zone drying furrow irrigation (PRD) using the same water volume per irrigation, in both methods. Two initiation timings (early and late) were tested under shelter and field conditions, the water supplied during every irrigation being 50% of the crop water demand calculated for furrow full irrigation (FI, as control). The comparison of both methods was done through the assessment of tuber fresh-yield and estimated economic and environmental (carbon footprint and irrigation water use efficiency, WUE_i) benefits. Late PRD and DI produced the highest WUE_i without significant yield reduction. PRD produced 3.1% higher net benefit than DI with an estimated CO₂ emission of 3659 kg ha^?1 CO₂ (14% lower than DI). The input-output ratio (total input costs/yield output) for PRD was 0.4, which was 10% lower than DI. The study’s results suggested that PRD, with no less than 50% of the water applied in FI per application, not only maintained yield but could also increase revenues while saving water and reducing CO₂ emissions, compared to DI. Such results might help reduce the pressure on the water reserves in semi-arid potato-producing areas in China. Notwithstanding, a scaling-up of PRD technology must be tested in those regions to substantiate the findings of this preliminary study.     

Alaska red: A general purpose,productive, red-skinned potato

‘Alaska Red’ is the first red-skinned potato bred and selected in Alaska as a clone suitable for the fresh potato market. Its parents are Alaska Clone 11-57-1-59 and ‘Red Beauty’. It is a high yielding, medium specific gravity potato with uniform skin and eye basin color, shallow eyes, uniform oval-to-flattened shape and is very attractive. The flesh is snowy white and remains white after boiling. Alaska Red keeps well in storage at 38°F (3.3°C). Scab of the tubers is the only disease that has been observed. In this subarctic region, flowers abort in the early bud stage. Red-skinned potato varieties available to Alaskan growers for the past quarter century have been unsatisfactory due to one or more of the following characteristics: low dry matter content, poor yield, uneven skin pigmentation and internal or external tuber cracking. Although consumers buy far less red than white-skinned potatoes, the demand brings Florida “reds” to Alaska as well as “reds” from other regions so that there is a year round outlet. Imported “reds” never approach the high quality of Alaskan grown “reds”. During the screening of seedlings, ‘Red Beauty’ was selected as a parental line because of its excellent conformation, skin color and eye arrangement. Low yield and shatter cracking made it unsuitable for commercial production. Alaska Red is a selection from seedlings of the cross Ak. 11-57-1-59 and Red Beauty made in 1965 and is the first red-skinned potato released from Alaska’s potato breeding. It was first evaluated by potato growers in 1972 and released in 1976 by the Agricultural Research Service, United States Department of Agriculture, Box AE, Palmer, Alaska 99645.     

Specific Gravity,Dry Matter and Starch Concentration of Different Potato Cultivars as Affected by Arsenic Contamination

Arsenic (As) contamination of the soil may affect the quality of potato tubers. When assessing the processing quality of potato cultivars, specific gravity (SG) is the measurement of choice for estimating dry matter (DM) and starch concentrations in the potato tubers. In this study, effects of the As concentration in the soil on quality parameters (SG, DM, starch concentration and total soluble solids (TSS)) of 11 potato cultivars in Bangladesh were investigated in an outdoor pot experiment with a randomized complete block design (RCBD) and three blocks, at Sher-e-Bangla Agricultural University, Dhaka, Bangladesh, from November, 2012 to March, 2013. The results showed highly significant differences between cultivars in quality parameters, except SG. Both As levels (25 and 50 mg As kg^?1 soil) reduced the DM and starch concentration in the tubers of the potato cultivars compared to the control (0 mg As kg^?1 soil), but had no significant effects on SG and TSS. ‘Lady Rosetta’ showed the highest SG (1.093 g cm^?3), DM (23.02%) and starch concentration (16.60%). The lowest SG (1.065 g cm^?3), DM (17.04%), and starch concentration (10.96%) was found in ‘Granola’. Highest TSS (5.91) was found in ‘Jam Alu’ while ‘Meridian’ had the lowest °Brix value (3.76). Bangladeshi potato farmers will benefit from the information generated regarding potato cultivation under As affected areas.     

Control of citrus postharvest penicillium molds with sodium ethylparaben

The curative antifungal activity of postharvest sodium ethylparaben (SEP) treatments against citrus green mold (GM) and blue mold (BM) was determined on different citrus species and cultivars artificially inoculated with Penicillium digitatum or Penicillium italicum and incubated at 20 °C and 90% RH for 7 d or stored at 5 °C and 90% RH for 8 weeks plus 7 d of shelf-life at 20 °C. The best concentration was selected in in vivo primary screenings with ‘Valencia’ oranges. SEP at 80 mM was tested at 20, 50 or 62 °C for 30, 60 or 150 s in small-scale trials to determine the best dip treatment conditions. Dips of 80 mM SEP at 20 °C for 60 s were selected and applied alone or in combination with 25 μL L⁻¹ of the conventional fungicide imazalil (SEP + IMZ 25). Imazalil at the very low concentrations of 25 (IMZ 25) or 50 μL L⁻¹ (IMZ 50) was also tested. Effectiveness of SEP alone at 20 °C for 60 s was significantly higher on oranges (cvs. ‘Valencia’ and ‘Lanelate’) than on mandarins (cvs. ‘Clemenules’, ‘Nadorcott’ and ‘Ortanique’), with GM and BM incidence reductions of up to 57–73% after 7 d at 20 °C. SEP was compatible with IMZ 25 and consistently improved its performance, irrespective of citrus cultivars and storage conditions. All treatments were less effective on ‘Clemenules’ mandarins. On ‘Valencia’ oranges stored for 8 weeks at 5 °C and 7 d at 20 °C, the combined treatment was significantly more effective than the single treatments (reductions of GM and BM incidence of about 96–93% and 55–39%, respectively). In additional tests, SEP, IMZ 25 and the combination applied at 20 °C for 60 s prevented GM on ‘Valencia’ oranges treated, inoculated with P. digitatum 24 h later and incubated at 20 °C for 7 d. It can be concluded from these results that SEP might be an integrating nonpollutant control alternative to be included in citrus postharvest disease control programs in the future.     

Performance of drip-irrigated dry-seeded rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) in South Asia

Drip irrigation in dry-seeded rice (DSR) is a new water-saving cultivation technology; however, very little is known of its productivity and water-saving capacities. The study was conducted for 2 years (2013 and 2014) in a split-plot design in three replicates with treatment combinations of four irrigation regimes [drip irrigation at 1.5, 2.25, and 3.0× pan evaporation (Epan) and flood irrigation at 3.0× Epan] and three nitrogen (N) levels (120, 150, and 180 kg ha^?1). Drip irrigation in DSR resulted in higher grain yield (7.34–8.01 t ha^?1) than flood irrigation (6.63–7.60 t ha^?1) , with water savings of more than 40 %. Water-use efficiency with drip irrigation was higher (0.81–0.88 kg m^?3) than flood irrigation (0.42–0.52 kg m^?3) , being highest with drip irrigation at 1.5× Epan. Root density at soil depths of 15–30 cm was also higher in drip (0.86–1.05 mg cm^?3) as compared to the flood (0.76–0.80 kg m^?3)-irrigated crop. This study implicated that under water-scarce scenario, drip-irrigated DSR is a profitable, and water- and energy-saving technology. This study also suggested that policy focus in future must be tilted towards the promotion of solar-operated drip irrigation in those regions, where DSR is being promoted in the face of water and energy crisis.     

Effects of drip irrigation regimes on potato tuber yield and quality under plastic mulch in arid Northwestern China

Field experiments were conducted to study the effects of drip irrigation regimes on potato (Solanum tuberosum L.) growth, tuber yield and quality, and water use efficiency (WUE) when grown under plastic mulch in an arid area of Northwestern China in 2008, 2009 and 2010. The 2008 experiment consisted of a drip irrigation check without plastic mulch and four different drip irrigation frequency treatments with plastic mulch: once every day, once every 2 days, once every 4 days, and once every 8 days. In 2009 and 2010 the drip check treatment without mulch was irrigated at −25 kPa soil matric potential (SMP) during three potato development stages and four different SMP drip irrigation strategies were compared during the potato development stages (using plastic mulch): S1 (−25 kPa SMP during the three development stages), S2 (−25 kPa SMP during tuber initiation and bulking and −35 kPa SMP during maturation), S3 (−25 kPa SMP during tuber initiation and maturation and −35 kPa SMP during bulking), S4 (−35 kPa SMP during the three development stages). Plastic mulch negatively affected tuber yield, WUE, and tuber quality. In the presence of plastic mulch, tuber yield, specific gravity, starch content, and vitamin C content seemed to be enhanced as the irrigation frequency increased, although the differences were not statistically significant. Irrigation frequency did not affect WUE for potato grown under plastic mulch. Analysis of plant height, tuber yield and WUE showed that a drip irrigation threshold of −35 kPa SMP led to obvious water stress for potato growth in this arid area. Under plastic mulch in 2010, S2 was the optimum drip irrigation regime because of the significantly higher yield than S3 and S4, the highest WUE and significantly firmer tubers than any of the other irrigation regimes tested.     

覆膜滴灌对玉米光合特性、物质积累及水分利用效率的影响

采用田间试验方法,以雨养条件为对照,研究3种灌溉处理(滴灌、覆膜滴灌、覆膜限量补灌)对玉米相对叶绿素质量浓度(SPAD值)、光合特性及产量和水分利用效率的影响,探讨不同膜下滴灌节水增产的效果及内在机制。结果表明,覆膜增加玉米苗期叶绿素质量浓度,在拔节期覆膜的作用减弱,抽雄期SPAD值依次为覆膜限量补灌覆膜滴灌滴灌雨养。与对照相比,覆膜滴灌、覆膜限量补灌玉米地上部干物质重分别增加22.8%~52.8%和20.3%~48.0%;玉米产量增加1 261 kg/hm2和1 300 kg/hm2,增产12.7%和13.1%;提高水分利用效率0.83 kg/m3和1.23 kg/m3,提高水分生产效率0.30 kg/m3和0.36 kg/m3。覆膜限量补灌在不影响光合产物积累的基础上,比覆膜滴灌节水60%。     

Root distribution under seepage-irrigated potatoes in Northeast Florida

Much of commercial potato production in Florida is irrigated using sub-surface seepage irrigation. A perched water table is maintained during the season within 50 cm below the top of the potato ridge. Fertilizer placement is critical in this system to maximize plant uptake and to minimize leaching potential. Optimal placement of fertilizers is dependent on root distribution. The objectives of this study were to develop and test a new methodology to spatially describe potato root distribution as affected by nitrogen rate and irrigation system. Soil slices containing representative samples of the potato root system at full flowering were taken from plots fertilized with ammonium nitrate at 168, 224, and 280 kg N ha^?1. The proposed sampling methodology performed satisfactorily. Root length density (cm root cm^?3 soil) and specific root length (cm root mg^?1 root dry weight) were not affected by nitrogen rate, but were affected by spatial position in the soil profile. The highest root length density value (0.72 average) was observed within 12 to 15 cm of the seedpiece. Low root length density values averaging 0.036 were observed between 24 and 36 cm from the top of the ridge. Specific root length values indicated a relatively homogeneous root system in terms of the quantity of invested biomass by unit of root length except in the two central units below 24 cm from the top of the ridge where thickened roots caused significant lower values averaging 6.47 as compared with the average of 15.87 from the surrounding Units in the slice. Root thickening in deep apical roots suggested aerenchyma formation promoted by a combination of saturated soil conditions in the root zone caused by inappropriate irrigation management and soil compaction. Fertilizer placement under the seedpiece should be a good alternative to increase potato nitrogen uptake under seepage irrigation.     

追氮对膜下滴灌马铃薯氮素吸收积累规律及利用效率的影响

以紫花白为试验材料,研究了不同追氮处理对膜下滴灌马铃薯氮素吸收积累规律及其利用效率。结果表明:随施氮量的增加,马铃薯对氮素的吸收和积累都呈增加趋势,而氮肥利用率及生产效率都呈递减趋势;施氮量为270.0 kg/hm2时,马铃薯氮素含量、累积吸收量最大;施氮量为67.5 kg/hm2时,氮素利用效率最高;而施氮量为202.5 kg/hm2时,产量最高。马铃薯块茎产量与氮素吸收量、氮素利用率存在显著正相关,而与施氮量相关不显著,氮素吸收量与施氮量呈极显著正相关。     

High-Resolution Aerial Imaging Based Estimation of Crop Emergence in Potatoes

Plant emergence and stand establishment are key indicators of early crop development that are routinely assessed in potato agronomy and crop improvement research. The standard method for evaluating emergence is through manual plant counts at regular intervals. In this proof-of-concept study, unmanned aerial vehicles integrated with multispectral imaging were used for high-throughput evaluation of crop emergence under field conditions. High-resolution aerial imaging was performed at 15 m above ground level to capture data from potato plots of two varieties (‘Alturas’ and ‘Payette Russet’) in which the seed had been treated with different concentrations of growth regulators (including non-treated controls). The treatments resulted in differences in plant emergence and establishment. The images were collected at 32, 37, and 43 days after planting (DAP). Image-based features such as plant count, SUM-NDVI, and SUM-BINARY were computed from normalized difference vegetation index (NDVI) images for each treatment plot using ArcGIS^®. The Pearson’s correlation coefficients (r) were significant (p < 0.05) between image-based plant counts (r = 0.82) and SUM-NDVI (r = 0.62-0.73) with that of manual plant counts for both varieties, especially at early growth stages (32 DAP) when differences in emergence among treatments were more pronounced. The treatment effects on plant emergence and establishment were effectively resolved in the aerial multispectral images. Selection of the pertinent polygon threshold area to eliminate noise in delineating individual plants during image processing was important for resolution of treatment effects. The data shows that the technique can be applied in potato establishment evaluation.