Comparison of Mineral Oil and Rapeseed Oil Used for the Protection of Seed Potatoes against PVY and PVM Infections

The aim of this research was to compare the effectiveness of mineral oil with rapeseed oil in the protection of potato seeds against Potato virus Y (PVY) and Potato virus M (PVM) infection. The research was carried out under field conditions in the north of Poland, in the Department of Potato Protection and Seed Science of the Plant Breeding and Acclimatization Institute??National Research Institute at Bonin. The effects of oil protection on potato seed infection by viruses, yield, and its structure and phytotoxity were assessed. Two rapeseed oils and one mineral oil were used: Olejan 85 EC (85% of natural rapeseed oil), alimentary oil Marlibo (100% of natural rapeseed oil) and Sunspray 850 EC (98.8% mineral oil+1.2% emulsifier). The effectiveness of oils in protection against PVY and PVM tuber infection was tested on two cultivars (Clarissa and Rosalind), which have a different level of resistance to the two viruses. The assessment of phytotoxicity was carried out on 10 potato cultivars from different earliness groups (Augusta, Bryza, Cekin, Clarissa, Impala, Krasa, Rosalind, Satina, Velox). Two oil concentrations, 2% and 4% were applied. During the growing period, eight to nine oil treatments were applied at 7-day intervals. The effectiveness of rapeseed oils against PVY and PVM was much weaker than that of the mineral oil and for the susceptible cultivar the percentage infected tubers did not differ significantly from untreated crops. However, Olejan 85 EC deserves attention as it significantly reduced PVY infection across years in the more resistant cultivar, especially in the case of a lower concentration (2% vs. 4%). When there are no other means of protection to use on organic seed plantations, this oil can be used as an alternative, especially in the case of cultivars which are moderately resistant to PVY. A disadvantage of its application may be the fact that in some years symptoms of phytotoxicity on potato plants were recorded and a lowering of tuber yield.     

马铃薯的养分需求

在综合了大量国内外关于马铃薯植株需肥研究资料的基础上,运用Excel进行统计分析生产1 000 kg马铃薯块茎的植株需肥量及影响其需肥的因素。结果表明,概率较高的1 000 kg马铃薯需N、P2O5、K2O的区间分别是3.0～4.0 kg,1.00～1.50 kg,4.0～6.0 kg。影响马铃薯养分需求量的因素有土壤有机质含量、土壤pH值、年份、产量等。明确单位产量的马铃薯需肥量及其影响因素,以期对我国的马铃薯测土配方施肥提供依据,对马铃薯因环境条件的差异而确定施肥量提供有益的信息。     

Demand for Processed Potato Products and Processing Quality Potato Tubers in India

Potato processing in India has shown a tremendous growth in the recent past, creating a proportionate increase in demand for processing quality potatoes. Reliable annual demand estimates of processing quality potato tubers in India were not available; hence, the current study was undertaken to provide such estimates. The study was based on a survey of 442 households in the state Maharashtra in India, which was regarded to be representative for India in the consumption of processed potato products. The annual expenditure on potato products during 2006–2007 in Maharashtra was estimated to be INR 5,254 million (€ 93.82 million), which was equivalent to 28,148 Mg of physical processed potato products and 83,333 Mg of processing quality potato tubers (0.38% of national potato production during 2006–2007, i.e. 22.09 million Mg). When the estimates were generalised to a national level, the requirement of processing-quality potato tubers in 2006–2007 was equal to 4.04% of national potato production. The forecasted annual demand of potato products in Maharashtra during 2011–2012 was 75,375 Mg and the corresponding demand of processing quality potato tubers was 230,760 Mg (0.75% of the estimated national potato production during 2011–2012, i.e. 30.89 million Mg). When generalised at national level, the demand of processing quality potato tubers during 2011–2012 was found to be 8% of the estimated national potato production.     

Three-dimensional Stochastic Shape Modelling for Potato Tubers

Tuber shape is a genetically determined, important varietal characteristic that is also influenced by environmental factors. In this study, the overall dimensions of tubers of two potato cultivars (Van Gogh and Yukon Gold) were determined using a triaxial ellipsoid model that was found to encompass the main varietal differences. The more detailed surface features were captured using a spherical-harmonics series representation for the residual undulation. The method was then applied to four additional cultivars (Bellona, Lady Rosetta, Pito, and Sabina). Modelling the undulation of tuber surface in addition to the overall dimensions indicated that cultivars differed in the global shape and, in specific cases, also in the surface undulation of tubers. The new, improved method for modelling tuber shapes can thus capture and distinguish the overall three-dimensional shape and irregularities caused by growth conditions and other factors. It is envisaged to be useful for quantitative genetics approaches aiming to resolve the relative impact of different genes on tuber shape, as well as for various machine vision and other applications.     

马铃薯块茎休眠及休眠调控研究进展

系统介绍了马铃薯块茎休眠的总体特征以及休眠块茎在细胞生理学方面的研究进展.同时还论述激素对马铃薯块茎休眠的调节作用,并提出了一些打破休眠的方法。     

马铃薯块茎钾含量近红外模型的建立

为了快速测定马铃薯块茎中的钾含量这一品质性状,从而缩短育种时间,本研究使用InfraXact Lab型近红外分析仪测定马铃薯样品的近红外光谱值,并用常规化学分析方法测定马铃薯样品的含钾量,将这二者拟合建立定标模型。结果表明:钾含量定标方程的SECV值为0.072,而1-VR值为0.881,较接近1,钾含量的验证参数SEP(C)值为0.080,RSQ值为0.866,证明定标的预测能力较好,可以用其进行马铃薯育种材料钾含量的粗略测定。     

马铃薯块茎还原糖的测定方法比较

对传统的铜还原-碘量法和3,5-二硝基水杨酸比色法测定块茎烘干样中的还原糖进行了比较研究。结果表明,比色法的准确性和精密性均稍好于铜还原-碘量法,且操作简便、快速、环境及人为因素对其影响较小。     

影响马铃薯块茎品质性状的环境因子分析

马铃薯品质主要取决于块茎成分及其含量,包括淀粉、蛋白质、糖和维生素等。块茎内各成分的含量除受遗传基础和生理特性控制外,还主要因自然生态环境条件和人为栽培因素的不同而发生变化。本文主要介绍了影响马铃薯品质性状的光照、温度、水分、土壤特性等自然生态环境因素,以及种植密度、肥料、病虫害等人为栽培因素。通过对影响马铃薯块茎品质性状的生态条件和栽培因素的分析,进一步了解块茎品质与环境因子的相互关系和作用机理,为马铃薯引种工作提供一定的科学依据。     

Cryotherapy of Potato Shoot Tips for Efficient Elimination of Potato Leafroll Virus (PLRV) and Potato Virus Y (PVY)

Viral diseases constitute a major constraint to high yield and high quality production of potato. Potato leafroll virus (PLRV) and Potato virus Y (PVY) are among the most damaging potato viruses and are prevalent in most potato growing areas. In the present study, attempts were made to eliminate PLRV and PVY by three cryogenic protocols, i.e., encapsulation-dehydration, encapsulation-vitrification and droplet. Results showed that both PLRV and PVY could be efficiently eliminated by cryogenic treatments with 83–86% and 91–95% of frequencies of virus-free plantlets obtained for the former and latter, respectively. Frequencies of virus-free plantlets produced by cryogenic treatments were higher than those by meristem culture (56% for PLRV and 62% for PVY) and thermotherapy (50% for PLRV and 65% for PVY), and similar to those by thermotherapy followed by meristem culture (90% for PLRV and 93% for PVY). Survival (75–85%) and regrowth (83–89%) from cryo-treated shoot tips were higher than those from meristem culture (50–55%) and thermotherapy followed by meristem culture (40–50%), but similar to those from thermotherapy (80–87%). The morphology of the plantlets regenerated from cryo-treated shoot tips was similar to that of non-treated plantlets. Thus, cryotherapy would provide an alternative method for efficient elimination of potato viruses, and can be simultaneously used for long-term storage of potato germplasm and for production of virus-free plants.     

马铃薯不同品系贮藏期品质分析

马铃薯秋天入窖后,测定不同品系的还原糖含量、可溶性糖含量、淀粉含量,其结果为:还原糖含量入窖后到次年3月份逐渐升高,之后又快速下降,6-21还原糖含量最低,小白花还原糖含量最高;可溶性糖含量较稳定,只是不同品系表现趋势不同,6-21可溶性糖含量最低,1-38可溶性糖含量最高;淀粉含量也较稳定,6个品系总趋势为逐渐下降;1-38淀粉含量最高;大多数马铃薯品系的还原糖与可溶性糖呈正相关,可溶性糖与淀粉、还原糖与淀粉呈负相关。     

The Use of Mineral Oil in Potato Protection: Dynamics in the Plant and Effect on Potato Virus Y Spread

The focus of this study was to evaluate two mineral oils (Superior 70 and Vazyl-Y) in reducing the seasonal spread of Potato Virus Y (PVY). Three concentrations of oil (0, 5, and 10 L ha^?1 of Superior 70; 0, 7.5, and 15 L ha^?1 of Vazyl-Y) and three spray regimes for both oils (every 3–4, 7, and 10–11 days) were tested. Two weeks after top-kill, two tubers from each of 49 plants free of virus at emergence were harvested from treatment plots, sprouted, and tested for PVY with enzyme-linked immunosorbent assay (ELISA). Results revealed that in the case of Superior 70, PVY spread in mineral oil treated plots ranged from 2.1 to 12.2 %, while in the control plots it ranged from 20.4 to 37.7 % across three cultivars. In the case of Vazyl-Y, PVY spread in mineral oil treated plots ranged from 2.1 to 26.5 %, while in the control plots it ranged from 49.9 to 85.7 % across three cultivars. These data show that there was a significant reduction in PVY due to spray of mineral oils. In addition, mineral oil was quantified in plants from the Superior 70 treated and the control plots to understand the dynamics of mineral oil during the season. While there was little to no oil measured in the leaves at the early stages of plant growth, a considerable amount of mineral oil was detected close to plant maturity. A basic model of the concentration of oil in the treated foliage was formulated to confirm our understanding of the factors at play. The model could explain from 50 to 90 % of the variation in oil content observed in the field. Plant growth and size are important factors affecting oil content in mineral oil treated foliage.     

Glycoalkaloid Concentration in Potato Tubers Related to Storage and Consumer Offering

Steroidal glycoalkaloids (SGA) are unwanted potato constituents for consumers because they are highly toxic and therefore have to be controlled in the food chain. Three experiments were carried out focusing on storage aspects and on exposure to artificial light at the point of sale. The experiments showed that an elevated temperature (10 °C) during long-term storage without sprouting inhibitors led to an increase in SGA contents (up to 518 mg SGA kg⁻¹ dry matter) in two of three investigated cultivars independent of the sprouting level. Cold storage (4 °C) slightly enhanced SGA contents in two cultivars. Sprout control resulted in a tendentious decrease in SGA contents in a set of another three cultivars. Growing location and wet and cool seasons had an influence too. Moderate exposure to light resulted in an increase in SGA in autumn, but in a decrease in spring time. Again, cultivars tested responded differently. The addressed factors have to be considered when developing strategies in minimising SGA level in table potatoes.     

马铃薯杂交组合实生薯留种试验

2003年我所从国际马铃薯中心(CIP)引进了16个杂交实生种子组合,春季在昆明市进行了筛选试验,收取了各组合的一代实生薯,并在当年冬季播种进行产量比较试验,结果表明:A4、A12两个组合在试验中产量较高,其抗病性、经济薯率及综合性状表现较好,具有推广应用前景;A系列杂交实生籽一代薯做种种植,与昆明地区大面积小春种植的中甸红和会-2号品种生育期相近,可以在我市小春上推广种植。     

Nucleotide Sequence Variability at the 5′-UTR of Potato PVY Isolates

Potato virus Y (PVY) isolates from potato were divided into two major groups – I and II – on the basis of nucleotide sequence variability at the 5′-UTR of the virus genome. In this paper, a consensus sequence for each group was compiled by examining PVY isolates of potato. The consensus sequences of the two groups differed from each other by as much as 31% of nucleotide sequence divergence. However, sequences of most individual members within each group (except for one, the 605 strain) were conserved and varied by less than 1% in group II and up to 6% in group I. These results confirm that the two virus groups are markedly distinct but that the 5′-UTR sequence of individual members within each group is highly conserved. These findings imply that the 5′-UTR can be reliably applied for major grouping of isolates but that its use for discrimination among individual isolates within each group is limited. Isolates of both group I and II included members of the O/N-NTN virus types. Classification of PVY isolates in potato is discussed.     

Effect of Growth Regulators and Ethanol on Termination of Dormancy in Potato Tubers

The main objective of this study was to find the best practice of inducing the sprouting of dormant potato tubers. We compared two protocols of breakage of dormancy, which are based on dipping excised potato eyes in an aqueous solution of gibberellic acid (GA₃) and kinetin (standard 1) or in the aqueous solution of GA₃, thiourea, and daminozide (standard 2), with a newly reported approach based on ethanol. We tested the effect of ethanol alone or in combination with GA₃ and/or kinetin on dormancy release and sprouting of the potato tubers. As a model, we used two potato genotypes (cultivars Pasat and Dorota), with long dormancy of 5 and 10 weeks respectively. We showed that the standard 2 was the most effective treatment both for dormancy breaking and in promoting sprout growth, especially for cv. Dorota, for which the treatment induced 82.3% of tuber eye-plugs to sprout 28 days after treatment and to produce 93.2% of emerged plants after subsequent 28 days of cultivation in the greenhouse. For this cultivar, similar efficacy was observed for the combination of 4% ethanol with GA₃ and kinetin. The same concentration of ethanol combined with GA₃ but without kinetin was the most efficient treatment for breaking dormancy of cultivar Pasat. However, the difference between the various treatment combinations was statistically insignificant. Ethanol alone or in combination with kinetin poorly induced breakage of dormancy, confirming the main role of GA₃ in artificial dormancy breaking. Thus our study showed that the standard 2 is the most effective approach for breakage of dormancy at least with long term-dormancy cultivars.     

Control of the Potato Virus X Through Application of Root Extracts of Chlorophytum nepalense to Potato Plants and Tubers

The perennial herb Chlorophytum nepalense (Lindley) Baker, widely distributed throughout the northern parts of Tripura State of India, is used traditionally by Tripuri farmers as a root extract to control dark viral necrotic lesions of sprouted potato tubers and plants. The root extracts strongly reduced infection of potato plants and sprouted tubers by Potato virus X under glasshouse conditions. The root extract was found to contain the three plant-viricidal compounds chlorogenic acid, kaempferol-3-O-(3′,6′di-O-E-p-coumaroyl)-β-d-glucopyranoside, and luteolin and suggests that the isolated compounds may have the potential to be used as natural plant-viricidal compounds.     

Susceptibility to Pressure Flattening Correlates with Texture Analysis of Potato Tubers

The physiological disorder referred to as pressure flattening is a cause of significant economic losses in the storage of Irish potatoes (Solanum tuberosum L.) intended for use in the fresh market. As the flattened area on each tuber becomes larger in diameter or becomes more depressed the USDA quality grade, and therefore the market value of the potatoes is reduced. Experiments were conducted to identify at-harvest which potato lots within and among cultivars were likely to pressure flatten earlier or more severely. The use of an instrumented penetrometer or texture analyzer to measure peak load required for periderm deformation at harvest appears to anticipate correctly the majority of fields from which tubers are more likely to have severe pressure flattening at six months’ storage duration. At-harvest texture analysis appears to segregate varieties according to susceptibility to deformation based on cultivar specific factors that play a role in pressure flattening development during storage. The Pearson correlation coefficient (R²=0.5481) indicates that there is a correlation between tuber texture at harvest and pressure flattened area on the tuber following storage. Testing of tubers from different fields and cultivars as the potatoes are loaded into storage, may allow growers to identify and ship potatoes that are more susceptible before they develop significant pressure flattening.     

Evidence of Recombinant Isolates of Potato Virus Y (PVY) in Argentina

In order to make a first approach in the identification of the genetic diversity of Potato virus Y (PVY) in Argentina, 46 PVY isolates from different potato growing regions of Argentina were characterized both, biological and serologically. Five of them (ST11, RCA5a, RCA6, RCA14b and SSF6) were selected for further genomic analyses. Four genomic fragments containing hot spot regions of recombination (HSR) reported previously were sequenced in each isolate and compared to PVY^N (CS434575.1) and PVY^O (U09509.1) reference genomes looking for genomic recombinations. Isolates with one, two or three recombination points were identified among these, including the two strains considered typical PVY^N (RCA5b) and PVY^O (SSF18) used as controls. This is the first report of the presence of recombined PVY in Argentina using a combination of biological, serological and molecular tools that shed light on the genetic diversity of PVY viruses in this country.     

Modification of ELISA by Replacing Incubation of Microtiter Plates in an Incubator with Their Shaking in PVY,PVM and PLRV Detection

ELISA (enzyme-linked immunosorbent assay) is a sensitive and reliable method of plant virus detection. It is commonly used in daily research carried out by scientific institutions and laboratories working on the certification of potato tubers. The key stage in this method is a 3–4-h-long incubation of microtiter plates with IgG and with a conjugate in an incubator at a temperature of 37 °C. The aim of the research was to replace this type of incubation process with a technique of mechanically shaking the plates using a shaker to induce a vibrating movement. Three durations of shaking, performed at room temperature, were adopted: 30, 60 and 90 min with two incubation periods at a temperature of 37 °C: 60 and 180 min which were applied at the stage of coating the IgG plates, following addition of the conjugate. The assessment was made for three dilutions of lyophilized sap from leaf of potatoes (1:10, 1:100, 1:1,000). Replacing the stages of plates incubation with IgG and conjugate at 37 °C with mechanical shaking allowed the whole process of DAS-ELISA to be reduced below 3–4 h without any significant impact on its quality. The process turned out to be equally efficient as the 3-h-long incubation in an incubator for PVY, PVM and PLRV detection by means of DAS ELISA. Applying the 90-min-long incubation on a shaker in comparison to a 3-h-long incubation in an incubator gave comparable or even slightly improved results. The reaction background, i.e. the value of absorbance for sap from healthy plants (negative control) was very low in all the combinations irrespective of the time of reading after the substrate was placed. No significant differences for this parameter were found between the combinations and times of reading. Only in the case of PLRV was a clearly visible decrease in test sensitivity found (no positive reactions) at diluted sap over 1:10. Moreover, it was observed that an increase in dilutions impacted the length of reaction. The dilution 1:10 seemed to be the most favorable (maximum 1:100 for PVY and PVM), wherein the sensitivity and pace of staining the substrate for each of the methods did not provoke any doubts regarding the reliability of the test.